Recommendations for Writing Empirical Journal Articles: Technical Report

Morton Ann Gernsbacher University of Wisconsin-Madison [email protected]

Open Science Framework September 18, 2017 https://doi.org/10.17605/OSF.IO/UXYCH

CONTENTS

1. Course syllabi that mention Bem’s “Writing the empirical journal article” chapter ……………………..…. p. 2 2. Word count and text of Clark and Clark’s (1939) classic article …………………………………………….. p. 8 3. Word count and text of Clark and Clark’s (1940) classic article …………………………………………….. p. 14 4. Word count and text of Clark and Clark’s (1947) classic article …………………………………………….. p. 21 5. Word count and text of Harlow’s “Nature of Love” (1958) classic article ………..…………..…………….. p. 27 6. Word count and text of Tolman’s “Cognitive Maps” (1948) classic article …………………...…………….. p. 49 7. Word count and text of Miller’s “Magical Number Seven” (1956) classic article ………………………….. p. 57

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8 Kenneth B. Clark and Mamie K. Clark (1939)

THE DEVELOPMENT OF CONSCIOUSNESS OF SELF AND THE EMERGENCE OF RACIAL IDENTIFICATION IN NEGRO PRESCHOOL CHILDREN

Cited by 741 [on Google Scholar as of SEP 13, 2017]

Journal of Social Psychology, S.P.S.S.I. Bulletin, 10, 591-599

Word Count from https://wordcounttools.com/ (excluding references, tables, and figures)

Speculations concerning the nature of the self and the development of consciousness of self have long been a significant part of psychology. Little experimental research has been done, however, in an attempt to raise this problem out of the maze of speculative conjectures. Piaget (9), elaborating upon Baldwin's (3) concept of a three stage development of "personal consciousness" (transitions from a "projective" to a "subjective" to an "ejective" sense of personality -- the final "ejective" stage being the social self wherein the child is aware of the fact that other people's bodies have similar experiences to his own), maintains that the child comes to discover himself through a progressive comparison of his own body with other people's bodies. Concerning the psychical qualities of self, he states: "In the same way, with regard to psychical qualities, it is by imitating other peoples' behavior that the child will discover his own."

Lewin (7) emphasizes the formation of the concept of property as a feature of the development of self consciousness: “The "I" or self is only gradually formed, perhaps in the second or third year. Not until then does the concept of property appear, of the belonging of a thing to his own person.”

G. W. Allport (1), on the other hand, speaks of an earlier consciousness devoid of self reference, while self consciousness develops only after the age of four or five years: “Until the child has a fairly definite conception of himself as an independent person, he cannot conceptualize his relationship to the surrounding world and hence lacks the subjective nucleus for the development of his own personality. … Even at the age of four or five the self, is by no means firmly encapsulated. … The advent of self consciousness is gradual, and its growth continuous, but a certain critical stage is reached around the age of two. … Its symptom is the period of negativism.” 9 Some experimental work on the problem has been done. Bain (2) made daily observations and records of a child's speech in normal family situations from birth to one and one-half years. From an analysis of the "self" and "others" words of the child he concluded that self is social; it appears and develops rapidly and observably from five months on and begins to be verbalized after about the first year. Bain said of the child:

It is out of his responses to others that his "consciousness of self" arise, together with appropriate verbal symbols for naming it. The "I" is a social concept. It is quite different from the concept of self as object which arises much later.

Goodenough (4), assuming the use of the first personal pronoun to be evidence of having reached a primitive stage in the development of self-awareness, studied the use of certain specified pronouns by children in free play and control situations. Pronouns of the first person singular were used with far greater frequency during free play with other children than in the controlled situation. The same trend was shown for the possessions my and mine.

Insofar as the use of these pronouns is indicative of something in the nature of an ego-consciousness, it is evident that this feeling is brought to the fore in the more competitive situations of group play far more frequently than is the case during the less socialized conditions of the controlled situation.

Moreno's (8) study is of interest in that it approaches the problem of the development of consciousness of self from the point of view of the dynamics of group development. He used a sociometric test wherein children chose from pictures of various racial groups the boy or girl whom they would like to have sit on either side of them. First and second choices were given. Moreno found that gradually from the first grade on the group develops a more differentiated organization. From about the fifth grade, a greater number of Italian children begin to choose Italian neighbors.

Attacking the problem of consciousness of self from the point of view of determining the spatial localization of the self, E. L. Horowitz (5) found that he was unable to present a final statement describing where the self actually is. He concludes that “the localization of the self … is not the basic phenomenon one might hope for to ease an analysis of the structure of the self and personality”

More recently, R. E. Horowitz (6) has been concerned with the problem of children's emergent awareness of themselves, with reference to a specific social grouping. Her study dealt with race consciousness conceived as a function of ego-development. Her procedure is described in detail because of its similarity to the one used in the present study. Two picture techniques were used with 24 children from two to five years of age: (a) Choice tests -- one pair of photographs for boys and girls respectively, showing a white child and a Negro child; one pair of line drawings showing a white boy and a Negro boy; one set of four-line drawings showing a white boy, a Negro boy, a chicken, and a clown. Boys were asked in each case to identify themselves. The form of the question was "Show me which one is you. Which one is " (using name of the subject). The girls, after having identified themselves in the first item, were asked to identify brothers or cousins in the three boy's items. (b) The Portrait Series -- 10 portrait pictures were exposed, one at a time. Children were asked, "Is this you? Is this ?" (using name of child). This latter technique did not give as satisfactory results as the first. In the Choice Tests Horowitz found that 68.4 per cent children were "correct" and 31.6 per cent were "incorrect." In the second series of line drawings more errors on the whole were made, "but the balance of errors was weighted in the same direction." In the third series of this technique, four of five Negro boys made "correct" identifications and three out of seven white boys made "correct" identifications.

The general limitations involved in the small number of cases are recognized by the author. She states: "Further work will, of course, have to be done to determine how common it is and within what framework of circumstance it operates."

THE PROBLEM

The present study is an attempt to investigate early levels in the development of consciousness of self in Negro preschool children with special reference to emergent race consciousness. The term consciousness of self may be considered as awareness of self as a distinct person; as distinct from other groups of things or individuals. The term race consciousness is here defined as consciousness of self as belonging to a specific 10 group which is differentiated from other groups by obvious physical characteristics. It is hereby assumed that race consciousness and racial identification are indicative of particularized self consciousness.

PROCEDURE

A modification of the Horowitz picture technique was used. There were three sets of line drawings as follows: Set A-one white boy, one colored boy, a lion and a dog; Set B -- one white boy, two colored boys and a clown; Set C -- two white boys, one colored boy and a hen. Combining all the line drawings there were four white boys and four colored boys. Each of the four pairs of white and colored boys was alike in every respect save skin color. The same white and colored boy never appeared in any one set of the pictures.

Materials and instructions were presented in the same manner as in Horowitz's investigation. "Show me which one is you. Which one is ______?" (using name of subject); with girls "Show me which one is ______?" (using name of brother, boy cousin or boy playmate). Subjects were examined individually.

Subjects: 150 Negro children in segregated Washington, D. C., nursery schools (75 male and 75 female-50 three-year-old, 50 four year-old, and 50 five-year-old children). These children were taken from five W.P.A. nursery schools, one private nursery school, and one public school kindergarten.

RESULTS

Table 1 presents the choices of subjects on the total picture series. On the entire series of pictures the total group of 150 Negro children made more choices of the colored boy (50.9%) than of the white boy (44.1%) (CR 2.13). This table, however, is meaningless from a genetic point of view, in that all age groups are combined. A mass presentation of the data completely disguises any factors which may be operative in the dynamics of self consciousness and racial identification.

It is apparent that there is a consistent increase in the differences between choices of colored and white boys with age. The significance of these differences increases thus: -2.7 per cent at the three year level (CR 0.4), to 10.9 per cent at the four-year level (CR 1.87), to 12.1 per cent at the five-year level (CR 2.08). These differences are in favor of the colored boy.

11 The absolute number of choices of colored boy increase from the three-year level (41.2%) to the four-year level (55.40/o) (CR 2.44) and slightly again at the five-year level (56.00/0) (CR 1.03). The number of choices of the white boy remain approximately the same at the three-, four-, and five-year levels.

Choices of the lion, dog, clown, and hen constitute 14.7 per cent of the total responses at the three-year level, but disappear at the four-year level and do not appear again at the five-year level. The increase in the percentage of choices of colored boy is at the expense of choices of the less relevant pictures of lion, dog, clown, and hen. Thus, beginning at the four-year level, these children cease to identify themselves in terms of the animals or the clown and consistently identify in terms of either the colored or white boys with a trend toward more choices of the colored boy.

The most significant aspect of the results presented in this table (Table 3) is the fact that the choices of the boys show significant trends whereas those of the girls seems to approximate chance. This fact can be best understood if it is remembered that the boys were making identifications of themselves while the girls were identifying brothers, cousins, and in a few instances a boy playmate. Because of this difference in response it would appear that either the technique used in this investigation has greater validity when used with boys than when used with girls, or that the dynamics involved when girls identify someone other than themselves is quite different from the self identification of the boys.

In view of the fact that the reason for this difference is at present unknown it is necessary to compare the choices of the boys alone with the choices of the total group. For choices of the colored boy by the males alone at each age level, there is a consistent increase is these responses with age from 31.5 per cent at the three- year level, to 60.8 per cent at the four-year level, to 63.0 per cent at the five-year level. This is in agreement with the general trend of results found for the total group. For choices of the white boy by the males, there is a consistent decrease in these responses with age from 50.7 per cent at the three-year level, to 39.1 per cent at the four-year level, to 36.9 per cent at the five-year level. For the total group, however, there is no such consistent decrease in the choices of white boy. An examination of Table 2 will show that for the three-, four-, and five-year level the percentages of choices of the white boy are respectively 43.9, 44.5, and 43.9. This stability is obviously due to the non-differential responses of the females.

DISCUSSION

It is clear cut from the results that a definite delimitation of the self on the part of these children occurs between the three- and four-year age levels. The dropping out of irrelevant choices of the lion, dog, clown, and hen indicates the attainment of a developmental level where consciousness of self is in terms of a distinct person.

This is undoubtedly a precursory level of development to the consciousness of belonging to one group as distinct from another. This latter contention appears to be justified by the increase in the number of choices of colored boy over white boy with age on the part of the total group, and is shown even more clearly in results for the males alone. The dynamic aspect in this development of self consciousness is even more apparent if one conceives of this increase in the number of choices of colored boy over white boy with age to be an indication of the emergence of the still higher level of personal racial consciousness.

The fact that definite age trends in increased choices of colored boy were evident from the three-year to the four-year level but, while continuing the trend, were not as definite (statistically significant) from the four-year to the five-year level indicates the probability that this technique is inadequate when used with higher age levels. 12 An alternative explanation of this finding would assume that it is an indication of the facts as they are; that the greatest (most significant) amount of development in self consciousness and racial identification, occurs between the third and fourth years. After the fourth year there is relatively little development of the mechanisms operative. This explanation would assume that the ceiling had been approached if not actually reached.

Obviously there must be a ceiling, but the data and incidental experiences of the investigators do not seem to warrant the assumption that the ceiling had been reached in this study by the technique used. In support of this belief is the fact that a few of the five-year old children refused to identify themselves with any picture, saying "I'm not on there," or "That's not me," or "I don't know them," etc. Some were hesitant, evidently because they thought the same. Some five-year olds said before making identifications on the first set of line drawings: "This is a white boy, this is a colored boy, this is a lion, and this is a dog." These responses gave an inkling of the fact that these five-year-olds were developing ideas of themselves as intrinsic individuals. It appeared to be a conflict with this idea for them to identify themselves with either the white or the colored boy, just as most of the three-year-olds and all of the four-year-olds had not identified themselves with any of the irrelevant drawings.

A more refined technique, which would be as sensitive for the five-year-olds as this one is for the three- and four-year-olds, would undoubtedly yield more valid information concerning the operation of this mechanism in the older children. Identification of self from line drawings seems to be too great an abstraction of an emergent concrete entity for the five-year-old boys. The hesitancy in interpreting self in terms of the line drawings, but rather conceiving of it as an intrinsic, concrete entity, is suggestive of another stage in the development of self consciousness.

The fair degree of significance of the male responses and the seeming chance responses of the females indicate that the line drawings used in this study should have been used exclusively with males for greatest validity. Line drawings of girls should have been used with the girls. The dynamics involved in identification of a brother or cousin on the part of the girls is obviously different from those in identification of one's self. Further data on the problem will appear in a later paper.

SUMMARY AND CONCLUSIONS

In an effort to get some indication of the nature of development of consciousness of self in Negro preschool children, with special reference to emergent race consciousness, 150 Negro children in segregated schools were shown a series of line drawings of white and colored boys, a lion, a dog, a clown, and a hen and asked to identify themselves or others. The results were as follows:

The total group made more choices of the colored boy than of the white boy.

The ratio of choices of the colored boy to choices of the white boy increased with age in favor of the colored boy.

Choices of the lion, dog, clown, and hen were dropped off at the end of the three-year level, indicating a level of development in consciousness of self where identification of one's self is in terms of a distinct person rather than in terms of animals or other characters.

The seeming chance responses of the girls warrants further study of girls making identifications of themselves on similar line drawings of girls.

The fact that the sharpest increase in identifications with the colored boy occurred between the three- and four- year level and failed to increase significantly at the five year level suggests that either this picture technique is not as sensitive when used with five-year-olds as when used with three- and four-year-olds, or that a plateau in the development of this function occurs between the ages of four and five, or that the five-year-olds have reached a stage in self-awareness which approaches a concept of self in terms of a concrete intrinsic self, less capable of abstractions or external representations.

13 REFERENCES

1. Allport, G. W. Personality: A Psychological Interpretation. New York: Holt, 1937. (Pp. 159-166.)

2. Bain, R. The self-and-other words of a child. Amer. J. Sociol., 1936, 41, 767-775.

3. Baldwin, J. M. Social and Ethical Interpretations in Mental Development. New York: Macmillan, 1897. (P. 7.)

4. Goodenough, F. L. The use of pronouns by young children: A note on the development of self-awareness. J. Genet. Psychol., 1938, 52, 333346.

5. Horowitz, E. L. Spatial localization of the self. J. Soc. Psychol., 1935, 6, 379-387.

6. Horowitz, R. E. Racial aspects of self-identification in nursery school children. J. of Psychol., 1939, 7, 91-99.

7. Lewin, K. Dynamic Theory of Personality. New York: McGrawHill, 1935. (Pp. 106.)

8. Moreno, J. L. Who Shall Survive? Wash., D. C.: Nervous and Mental Disease Publishing Co., 1934. (P. 61.)

9. Piaget, J. The Moral Judgment of the Child. New York: Harcourt, Brace, 1932. (P. 393.)

14 Kenneth B. Clark and Mamie K. Clark (1940)

SKIN COLOR AS A FACTOR IN RACIAL IDENTIFICATION OF NEGRO PRESCHOOL CHILDREN

Journal of Social Psychology, S.P.S.S.I. Bulletin, 11, 159-169

Cited by 366 [on Google Scholar as of SEP 13, 2017]

Word Count from https://wordcounttools.com/ (excluding references, tables, and figures)

Racial identification has been assumed to be indicative of a phase of the development of consciousness of self. Horowitz (2) conceives of the beginnings of race consciousness as a function of ego development. The authors (1) also assumed racial identification to be indicative of particularized self-consciousness. An investigation of the factors inherent in the genesis of racial identification would obviously lead to an understanding of the dynamics of self consciousness and its social determinants.

In a preceding paper the authors (1) presented results of an investigation of age and sex factors in racial identification. The present paper is an attempt to determine the influence of skin color as another factor in racial identification of Negro preschool children. Methodology, experimental procedure and subjects are identical with those used in the preceding investigation. However, the subjects are here divided, on the basis of skin color, into three groups; light, medium, dark. Moreover, only choices of white and colored boy are included in the analysis of results, excluding irrelevant choices (lion, dog, clown, hen) of some of the three-year olds. It seems necessary to state that the experimenter who actually worked with the children was medium brown in 15 skin color. This was fortunate in that it tended to neutralize the probable influence of as extremely light or dark investigator on the responses of the children.

When the data presented in Table 1 are analyzed for choices of the colored boy, it is found that the light children chose the colored boy 36.5 per cent, the medium children 52.6 per cent and the dark children 56.4 per cent. This shows a consistent increase (approaching statistical significance) in choices of the colored boy from the light to the medium group (CR 2.69). From the medium to the dark group the increase is negligible (CR 0.76). But from the light to the dark group there is a statistically significant increase as choices of the colored boy (CR 3.15).

Analyzing the data for choices of the white boy, there is a decrease in these choices from the light to the medium group (CR 2.38). The decrease is not statistically significant from the medium to the dark group (CR 0.16). However, from the light to the dark group the decrease in choices of the white boy is striking (CR 4.57).

An analysis of the data from the point of view of differences a between the percentage of choices of white and colored boy by each skin color group shows an increase in choice of colored boy over white boy, proceeding from the light through the medium to the dark group. The light group made 20.0 per cent more choices of the white boy than of the colored boy (a - 20.0 per cent choice of the colored boy; CR 2.77). The medium group chose the colored boy 10.9 per cent more than the white boy (CR 1.25) and the dark group made 15.9 per cent more choices in favor of the colored boy (CR 2.52). It is interesting that the highest difference in percentage of choices is found in the light group in favor of the white boy. The significance of this analysis remains, however, in the increase in percentage differences in favor of the colored boy proceeding from the light through the medium to the dark group.

The data from Table 1 show an almost reciprocal picture for choices of the extreme skin color groups of light and dark, identification of light children more with pictures of the white boy, and identification of dark children more with pictures of the colored boy. This would seem to establish the factor of skin color as an important one in the genesis of consciousness of self and racial identification.

The fact that light children chose the white boy many more times than the colored boy suggests an identification of self, not on the basis of socially defined racial group differences, but on the basis of physical characteristics within the specific racial group. That the same thing holds true in the other extreme group of dark children can be safely assumed. It may be stated that consciousness of self as different from others on the basis of observed skin color precedes any consciousness of self in terms of socially defined group differences in these Negro children.

The fact that the medium group closely resembles the dark group in making more choices of the colored boy than of the white boy seems to indicate that the same dynamics involved in the identifications of the dark children are operative in the identifications of the medium children. A fact which should be noted is that the classification of the medium group was more difficult and resulted in greater heterogeneity of subjects in respect to skin color. This would not, however, explain why the medium group aligned itself, with respect to choices, with the dark group rather than with the light group.

It is quite possible that this difference could be explained through an analysis of the light group. The factors resulting in a cleavage of this group from the other two groups might be inherent in the characteristics of the light group itself. This point of view finds some justification if the results are viewed as indicative of the light 16 group's deviation from the norm of choices of the other two groups. If so, then the extreme lightness of skin color must be conceived as marking off a distinctive group rather than as a mere difference in degree from the medium and the dark skin colors, and this fact responsible for the observed cleavage.

The results show clearly that an analysis of subjects upon the basis of skin color may not assume that the difference between the medium skin color group and the light group is equal to that between the medium and the dark group in reference to the inherent dynamics involved, in spite of the seemingly observed objective differences.

In the light of this rather definite result further analysis of these three groups is necessary before any real explanation or conclusion may be drawn. It is possible that other factors (age and sex) might have influenced the above mentioned results.

An analysis of the data for sex differentials disclosed one deviation from the results already presented; namely, the light males made more choices of the colored boy (58.6%) than of the white boy (41.3%). This result appears to be contrary to the general trend of the influence of the skin color factor on identifications. The small number of cases, 11, however, in this group of light boys as compared with the medium, 39, and dark, 25, groups of boys probably explains the existence of this deviation. Because of the small number of cases in each category of a male-female breakdown according to both skin color and age levels, it seemed advisable to mass all of the cases without regard to sex differences. This was done in spite of the fact that it was previously suggested (1) that the dynamics of the identification of brothers and cousins by the girls was somewhat different from those operative in the boys' identification of themselves. This possibility, however, does not appear to affect seriously the basis of the present analysis especially when it is seen that the medium and dark groups of males (with larger numbers of subjects) do not deviate from the general trend of the results from all subjects.

The male medium group chose in favor of the colored boy (56.1%) rather than the white boy (43.8%). The male dark group chose the colored boy 64.3 per cent and the white boy 35.6 per cent.

In spite of the small number of cases in the light group at each age, some trends for the three groups may be seen from Table 2.

At the three-year level, both the light and medium groups made more choices of the white boy than of the colored boy. The percentage differences in favor of the white boy are 7.7 per cent for the light group (CR insignificant) and 16.9 per cent for the medium group (CR 2.64). On the other hand the dark three-year-olds made more choices of the colored boy than of the white boy (CR 1.47). It would appear that the extreme groups of light and dark children are beginning to identify themselves on the basis of their own skin color, 17 whereas the medium group seems influenced by other factors in making identifications of self. It may be that these medium three-year-olds, not being on the extremes of skin color, have not yet reached the developmental level of self consciousness where identification of self is in terms of skin color. The apparent non-identification of the medium three-year-olds on the basis of their skin color as the determining cue is probably primarily due to the lack of definiteness of their own skin color when compared with the presented line drawings. On the other hand, the apparent trend of the medium three-year-old children may be due to the greater heterogeneity of skin colors in this classification -- an overweighting of this group with children "lighter than" others in the same skin color classification.

At the four-year level the light group again makes more choices of the white boy than of the colored boy (CR 2.37). However, the picture is changed for the medium and dark groups at this age. The medium group makes significantly more choices of the colored boy than of the white boy (CR 4.79). The dark group makes more choices of the white boy than of the colored boy (CR 1.10).

The persistence of the light group in identifying with the white boy and the increase in statistical significance of this difference at the four-year level further emphasizes identification of these children on the basis of their own skin color. The reversed trend of the medium group at this age level as compared with the three-year medium group and the statistical significance of their identifications in favor of the colored boy (CR 4.79) indicates the attainment of a developmental stage where identifications are now made in terms of awareness of skin color differences, particularly differentiating themselves from the light group.

A possible explanation of the tendency of dark four-year-old children to make identifications in favor of the white boy (CR 1.10) is that these children are conscious of being dark or of being different from the light children, but make identifications of themselves in a direction indicating "wishful thinking" by pointing to the white boy. The fact that the difference in choice in favor of the white boy is not more impressive statistically than it is would seem to call for more evidence. The five-year-old light children are still consistent in identifying themselves more with the white boy than with the colored boy (CR 2.16). The three-, four- and five-year-old light children have consistently made a greater percentage of identifications of themselves with the white boy. The percentage of choices of the white boy increases from the three-year (42.3%) to the four-year level (65.1 %) but decreases slightly at the five-year level (61.1%). This slight decrease in choice of the white boy by the light five-year-olds is, of course, concomitant with a slight increase in choice of colored boy. This slight trend may point in the direction of identifications on the basis of socially defined race; a developmental stage subsequent to identification on the basis of their own physical characteristics.

Although the five-year-old medium children make more choices of the colored boy than of the white boy the difference is entirely insignificant statistically as compared with the difference in favor of the colored boy at the four-year level (CR 4.79). In order to understand the decreased difference in choice of colored boy over white boy of the five year medium group as compared with the four-year medium group, it is necessary to keep in mind two facts; (a) the general instability of choices of the medium group as compared with the light and the dark group, and (b) the indicated lesser sensitiveness of the technique for the five-year-olds as contrasted with its sensitiveness for the three- and four-year-olds (1).

For the dark five-year-olds the choice of colored boy over white boy is striking (CR 21.21). In choices of the colored boy the data show an insignificant drop from the three-year (52.3%) to the four-year level (44.1%) (CR .08) and a sharp rise from the four-year to the five-year level (70.1%) (CR 3.42). Indications of the operation of the mechanism of "wishful thinking" were found to some extent only in the four-year-old dark children (choices were in favor of the white boy). This mechanism was not indicated to any appreciable extent in the three-year- olds, suggesting the possibility that the operation of the mechanisms of "wishful thinking" and phantasies in reference to self identification is too sophisticated an operation for the three-year-old developmental level. The five-year-old dark children seem to have abandoned almost entirely "wishful thinking" in favor of identifications based on the concrete fact of their own skin color.

When cases of children making consistent choices of either the a white boy or the colored boy (that is, choosing either boy consistently throughout the series of three pairs of line drawings of colored and white boys) are taken from the total group for analysis, the same trends for the skin color groups already discussed are even more evident. 18

Of the total group of 150 Negro children, 58 or 38.66 per cent were consistent in their choice of either the colored or the white boy. [1] Age was found not to be a factor in consistency of response since 40.0 per cent of the three-year-olds, 36.0 per cent of the four year-olds and 40.0 per cent of the five-year-olds were consistent.

Of the 30 light children in the total group of 150 children 47.0 per cent were consistent; 26.0 per cent of the medium children were consistent; and 50.0 per cent of the dark children were consistent. This lower percentage of consistent medium children again indicates the general instability and vacillation of choices of the medium colored children.

These data show that the consistent light children were choosing the white boy more than the colored boy by an appreciable percentage. The consistent medium children and the consistent dark children chose the colored boy over the white boy to the same degree as the light children did the reverse. This clearly substantiates the foregoing results from percentage of total choices.

The analysis of the data in terms of age levels for each consistent skin color group shows insufficient cases for presentation of the results in percentages. However, the general trend can be seen when the results are shown by the number of consistent children, as in Table 4.

Data in this table further substantiate the fact that skin color is a determinant in self identification of these children, with the same exception of the three-year-old medium children already noted above.

DISCUSSION

19 Horowitz (2) states that Negro children's identifications of themselves with the line drawings and pictures of white children could possibly be interpreted as "wishful activity," or as identifying one's self "not so much in terms of what one is as . . . in terms of what one is not." It is clear that the consistent identifications of the light children with the white boy strongly point in the direction of an awareness of self in terms of a concrete physical characteristic such as skin color. While it is still possible that the factor of "wishful activity" may be of some influence here in a few instances, it seems, however, too great an abstraction, in the face of the predominant concrete clue of the actual skin color of the light subjects to be seriously considered as a determining factor in this instance. It is only when the more concrete factors, e.g., dark skin color, would tend to militate against a given choice that one would be justified in utilizing intangible concepts for an interpretation of the results.

Although twice as many dark children were consistently choosing the colored boy, eight of them were consistently choosing the white boy. "Wishful activity" as an explanatory concept seems to be more plausible here-but at best not a very strong point in the face of lack of information concerning the effects of other factors on consciousness of self and racial identification; namely, intelligence and an understanding by the subjects of the concept of difference.

In a preliminary supplementary study an attempt was made by the authors to determine the number of children who were able to verbalize the actual skin color difference in the drawings of the white and colored boy. The awareness of this difference was expressed by the subjects' pointing to the drawings and saying something as follows: "He's white-and he's colored" or "A black boy -- a white boy." Among the four children positively indicating a skin color difference in this supplementary study and at the same time consistently choosing the white boy in the picture series three were light and one was medium. This result, if substantiated by a more extensive investigation, would definitely rule out "wishful activity" as an explanation of the choices of the white boy by these Negro children in the one instance in which it at present seems most applicable. Then too, the operation of "wishful activity" involves the following two factors: (a) The negation of concrete determinants of the self, and (b) an evaluation of alternatives and a definite decision as to the better of the two. This, in the light of the observed behavior of the children, seems wholly outside of their present scope.

In general, these results give little evidence of the operation of "wishful activity" in the identifications of the subjects and show clearly that identification of oneself is in terms of what one is rather than "what one is not."

Horowitz (2) states: "Judging from the choices of the children and their verbal comments, one may conclude that identification with the correct picture indicates an awareness of one's own skin color as a factor of differentiation and similarity." If this awareness of one's own skin color is actually a level of self consciousness preceding consciousness of socially defined racial differences, one would expect these light children to identify themselves with pictures of white children. Any interpretation of data in terms of correct identifications, i.e., identifications of Negro children with pictures of colored children, disguises significant findings. The fact that identification of the light children with pictures of the white boy is an indication of awareness of self in terms of one's own skin color is supported in this study by: (a) The fact that at all ages the light children made more choices of the white boy than of the colored boy; (b) the fact that light children showed a sharp increase in identification with the white boy from the three- to the four-year level and maintained this increase at the five- year level; (c) the fact that 10 out of 14 light children making consistent choices in the picture series chose the white boy rather than the colored boy; (d) the fact that of children verbally indicating a skin color or racial difference between the colored and white boys (supplementary study) and at the same time consistently choosing the white boy in the picture series, three out of the four were light in skin color.

The general tendency of the dark children to identify themselves with the drawings of the colored boy is not incompatible with the objective fact of their own skin color. This same thing holds true of the medium children with certain already stated modifications. There would be, however, a definite incompatibility if the majority of light children identified themselves with the drawings of the colored boy, hence the persistence of their identifications with the white boy. It is obvious that these children are not identifying on the basis of "race" because "race" is a social concept which they learn at a higher stage in their development. They are, however, definitely .identifying on the basis of their own skin color which is to them a concrete reality.

The results indicate a slight trend for the light children to make identifications contrary to the objective clue of their own skin color. This paradox increases with age and can best be interpreted as the approach to another 20 developmental stage in the consciousness of self. At this stage it appears that concepts of self gleaned from the concrete physical characteristics of perceived self become modified by social factors, taking on a new definition in the light of these social factors.

The implications of these results seem pertinent to an understanding of the genesis of the personality in general and "personality of minority peoples" in particular. Whatever the concepts of self in relation to society as found in Negro adolescents and adults, whether they result in adjustments or conflicts, they are certainly to be conceived as part of a total pattern of development in which these findings are primordial.

REFERENCES 1. Clark, K. B., & Clark, M. K. The development of consciousness of self and the emergence of racial identification in Negro preschool children. J. Soc. Psychol., 1939, 10, 591-599. 2. Horowitz, R. E. Racial aspects of self-identification in nursery school children. J. of Psychol., 1939, 7, 91-99.

Footnotes [1] That is, choosing the same boy (white or colored) three out of three times.

21 Kenneth B. Clark and Mamie P. Clark (1947)

RACIAL IDENTIFICATION AND PREFERENCE IN NEGRO CHILDREN

Readings in Social Psychology NEW YORK 1947 HENRY HOLT AND COMPANY

Cited by 1559 [on Google Scholar as of SEP 13, 2017]

Word Count from https://wordcounttools.com/ (excluding references, tables, and figures)

The specific problem of this study is an analysis of the genesis and development of racial identification as a function of ego development and self-awareness in Negro children.

Race awareness, in a primary sense, is defined as a consciousness of the self as belonging to a specific group which is differentiated from other observable groups by obvious physical characteristics which are generally accepted as being racial characteristics.

Because the problem of racial identification is so definitely related to the problem of the genesis of racial attitudes in children, it was thought practicable to attempt to determine the racial attitudes or preferences of these Negro children — and to define more precisely, as far as possible, the developmental pattern of this relationship.

Procedure

This paper presents results from only one of several techniques devised and used by the authors to investigate the development of racial identification and preferences in Negro children.' Results presented here are from the Dolls Test.

22 Dolls Test. The subjects were presented with four dolls, identical in every respect save skin color. Two of these dolls were brown with black hair and two were white with yellow hair. In the experimental situation these dolls were unclothed except for white diapers. The position of the head, hands, and legs on all the dolls was the same. For half of the subjects the dolls were presented in the order: white, colored, white, colored. For the other half the order of presentation was reversed. In the experimental situation the subjects were asked to respond to the following requests by choosing me of the dolls and giving it to the experimenter:

1. Give me the doll that you like to play with — (a) like best.

2. Give me the doll that is a nice doll.

3. Give me the doll that looks bad.

4. Give me the doll that is a nice color.

5. Give me the doll that looks like a white child.

6. Give me the doll that looks like a colored child.

7. Give me the doll that looks like a Negro child.

8. Give me the doll that looks like you.

Requests 1 through 4 were designed to reveal preferences; requests 5 through 7 to indicate a knowledge of “racial differences”; and request 8 to show self-identification.

It was found necessary to present the preference requests first in the experimental situation because in a preliminary investigation it was clear that the children who had already identified themselves with the colored doll had a marked tendency to indicate a preference for this doll and this was not necessarily a genuine expression of actual preference, but a reflection of ego involvement. This potential distortion of the data was controlled by merely asking the children to indicate their preferences first and then to make identifications with one of the dolls.

Subjects

Two hundred fifty-three Negro children formed the subjects of this experiment. One hundred thirty-four of these subjects (southern group) were tested in segregated nursery schools and public schools in Hot Springs, Pine Bluff, and Little Rock, Arkansas. These children had had no experience in racially mixed school situations. One hundred nineteen subjects (northern group) were tested in the racially mixed nursery and public schools of Springfield, Massachusetts.

Age distribution of subjects:

All subjects were tested individually in a schoolroom or office especially provided for this purpose. Except for a few children who showed generalized negativism from the beginning of the experiment (results for these children are not included here), there was adequate rap- port between the experimenter and all subjects tested. In general, the children showed high interest in and enthusiasm for the test materials and testing situation. The children, for the most part, considered the experiment somewhat of a game.

Results

Racial Identification. Although the questions on knowledge of “racial differences” and self-identification followed those designed to determine racial preference in the actual experimental situation, it appears more meaningful to discuss the results in the following order: knowledge of “racial differences,” racial self- identification, and finally racial preferences.

23 The results of the responses to requests 5, 6, and 7, which were asked to determine the subjects’ knowledge of racial differences, may be seen in Table 1. Ninety-four percent of these children chose the white doll when asked to give the experimenter the white doll; 93 percent of them chose the brown doll when asked to give the colored doll; and, 72 percent chose the brown doll when asked to give the Negro doll. These results indicate a clearly established knowledge of a “racial difference” in these subjects — and some awareness of the relation between the physical characteristic of skin color and the racial concepts of “white” and “colored.” Knowledge of the concept of “ Negro ” is not so well developed as the more concrete verbal concepts of “white” and “colored” as applied to racial differences.

The question arises as to whether choice of the brown doll or of the white doll, particularly in response to questions 5 and 6, really reveals a knowledge of “racial differences” or simply indicates a learned perceptual reaction to the concepts of “colored” and “white.” Our evidence that the responses of these children do indicate a knowledge of “racial difference” comes from several sources: the results from other techniques used (i.e., a coloring test and a questionnaire) and from the qualitative! data obtained (children’s spontaneous remarks) strongly support a knowledge of “racial differences.” Moreover, the consistency of results for requests 5 through 8 also tends to support the fact that these children are actually making identifications in a “racial” sense.

The responses to request 8, designed to determine racial self-identification follow the following pattern; 66 percent of the total group of children identified themselves with the colored doll, while 33 percent identified themselves with the white doll. The critical ratio of this difference is 7.6.*

Comparing the results of request 8 (racial self-identification) with those of requests 5, 6, and 7 (knowledge of racial difference) it is seen that the awareness of racial differences does not necessarily determine a socially accurate racial self- identification — since approximately nine out of ten of these children are aware of racial differences as indicated by their correct choice of a “white” and “colored” doll on request, and only a little more than six out of ten make socially correct identifications with the colored doll.

Age Differences. Table 2 shows that, when the responses to requests 5 and 6 are observed together, these subjects at each age level have a well-developed knowledge of the concept of racial difference between “white” and “colored” as this is indicated by the characteristic of skin color. These data definitely indicate that a basic knowledge of “racial differences” exists as a part of the pattern of ideas of Negro children from the age of three through seven years in the northern and southern communities tested in this study — and that this knowledge develops more definitely from year to year to the point of absolute stability at the age of seven.

A comparison of the results of requests 5 and 6 with those of request 7, which required the child to indicate the doll which looks like a “Negro” child, shows that knowledge of a racial difference in terms of the word “Negro” does not exist with the same degree of definiteness as it does in terms of the more basic designations of “white” and “colored.” It is significant, however, that knowledge of a difference in terms of the word “Negro” makes a sharp increase from the five- to the six-year level and a less accelerated one between the six- and seven-year levels. The fact that all of the six-year-olds used in this investigation were enrolled in the public schools seems to be related to this spurt. Since it seems clear that the term “Negro” is a more verbalized designation of “racial differences,” it is reasonable to assume that attendance at public schools facilitates the development of this verbalization of the race concept held by these children.

In response to request 8 there is a general and marked increase in the percent of subjects who identify with the colored doll with an increase in age — with the exception of the four- to five- year groups. This deviation of the five- year-olds from the general trend is considered in detail in the larger, yet unpublished study.

*Individuals failing to make either choice not included, hence some percentages add to less than 100.

Identification by Skin Color. Table 3 shows slight and statistically insignificant differences among the three skin-color groups in their responses which indicate a knowledge of the “racial difference” between the white and colored doll (requests 5 through 7). 24

It should be noted, however, that the dark group is consistently more accurate in its choice of the appropriate doll than either the light or the medium group on requests 5 through 7. This would seem to indicate that the dark group is slightly more definite in its knowledge of racial differences and that this definiteness ex- tends even to the higher level of verbalization inherent in the use of the term “Negro” as a racial designation. In this regard it is seen that 75 percent of the dark children chose the colored doll when asked for the doll which “looks like a Negro child” while only 70 percent of the light children and 71 percent of the medium children made this response. The trend of results for requests 5 and 6 remains substantially the same.

These results suggest further that correct racial identification of these Negro children at these ages is to a large extent determined by the concrete fact of their own skin color, and further that this racial identification is not necessarily dependent upon the expressed knowledge of a racial difference as indicated by the correct use of the words “white,” “colored,” or “Negro” when responding to white and colored dolls. This conclusion seems warranted in the light of the fact that those children who differed in skin color from light through medium to dark were practically similar in the pattern of their responses which indicated awareness of racial differences but differed markedly in their racial identification (responses to request 8 for the doll “that looks like you”) only 20 percent of the light children, while 73 percent of the medium children, and 81 percent of the dark children identified themselves with the colored doll.

It is seen that there is a consistent increase in choice of the colored doll from the light to the medium group; an increase from the medium group to the dark group; and, a striking increase in the choices of the colored doll by the dark group as compared to the light group. All differences, except between the medium and dark groups, are statistically significant.

Again, as in previous work, it is shown that the percentage of the medium groups’ identifications with the white or the colored representation resembles more that of the dark group and differs from the light group. Upon the basis of these results, therefore, one may assume that some of the factors and dynamics involved in racial identification are substantially the same for the dark and medium children, in contrast to dynamics for the light children.

North-South Differences. The results presented in Table 4 indicate that there are no significant quantitative differences between the northern and southern Negro children tested (children in mixed schools and children in segregated schools) in their knowledge of racial differences.

While none of these differences is statistically reliable, it is significant that northern children know as well as southern children which doll is supposed is supposed to represent a white child and which doll is supposed to represent a colored child. However, the northern children make fewer identifications with the colored doll and more identifications with the white doll than do the southern children. One factor accounting for this difference may be the fact that in this sample there are many more light colored children in the North (33) than there are in the South (13). Since this difference in self-identification is not statistically significant, it may be stated that the children in the northern mixed-school situation do not differ from children in the southern segregated schools in either their knowledge of racial differences or their racial identification. A more qualitative analysis will be presented elsewhere.

Racial Preferences. It is clear from Table 5 that the majority of these Negro children prefer the white doll and reject the colored doll.

Approximately two thirds of the subjects indicated by their responses to requests 1 and 2 that they like the white doll “best,” or that they would like to play with the white doll in preference to the colored doll, and that the white doll is a “nice doll.”

Their responses to request 3 show that this preference for the white doll implies a concomitant negative attitude toward the brown doll. Fifty-nine percent of these children indicated that the colored doll “looks bad,” while only 17 percent stated that the white doll “looks bad” (critical ratio 10.9). That this preference and negation in some way involve skin color is indicated by the results for request 4. Only 38 percent of the 25 children thought that the brown doll was a “nice color,” while 60 percent of them thought that the white doll was a “nice color” (critical ratio 5.0).

The importance of these results for an understanding of the origin and development of racial concepts and attitudes in Negro children cannot be minimized. Of equal significance are their implications, in the light of the results of racial identification already presented, for racial mental hygiene.

Age Differences. Table 6 shows that at each age from three through seven years the majority of these children prefer the white doll and reject the brown doll. This tendency to prefer the white doll is not as stable (not statistically reliable) in the three-year-olds as it is in the four- and five-year-olds. On the other hand, however, the tendency of the three-year-olds to negate the brown doll (“looks bad”) is established as a statistically significant fact (critical ratio 4.5).

Analyzing the results of requests 1 and 2 together, it is seen that there is a marked increase in preference for the white doll from the three- to the four-year level; a more gradual decrease in this preference from the four- to the five-year level; a further decrease from the five- to the six- year level; and a continued decrease from the six- to the seven-year level. These results suggest that although the majority of Negro children at each age prefer the white doll to the brown doll, this preference decreases gradually from four through seven years.

Skin color preferences of these children follow a somewhat different pattern of development. The results of request 4 show that while the majority of children at each age below 7 years prefer the skin color of the white doll, this preference increases from three through five years and decreases from five through seven years. It is of interest to point out that only at the seven-year level do the same number of children indicate a preference for the skin color of the colored doll as for that of the white doll.

The majority of these children at each age level indicate that the brown doll rather than the white doll, “looks bad.” This result shows positively the negation of the colored doll which was implicit in the expressed preference for the white doll discussed above.

The evaluative rejection of the brown doll is statistically significant, even at the three-year level, and is pronounced at the five-year level. The indicated preference for the white doll is statistically significant from the four-year level up to the seven-year level.

It seems justifiable to assume from these results that the crucial period in the formation and patterning of racial attitudes begins at around four and five years. At these ages these subjects appear to be reacting more uncritically in definite structuring of attitudes which conforms with the accepted racial values and mores of the larger environment.

Preferences and Skin Color. Results presented in Table 7 reveal that there is a tendency for the majority of these children, in spite of their own skin color, to prefer the white doll and to negate the brown doll. This tendency is most pronounced in the children of light skin color and least so in the dark children. A more intensive analysis of these results appears in a larger, yet unpublished study.

North-South Differences. From Table 8 it is clear that the southern children in segregated schools are less pronounced in their preference for the white doll, compared to the northern children’s definite preference for this doll. Although from still in a minority, a higher percentage of southern children, compared to northern, prefer to play with the colored doll or think that it is a “nice” doll. The critical ratio of this difference is not significant for request 1 but approaches significance for request 2 (2.75).

A significantly higher percentage (71) of the northern children, compared to southern children (49) think that the brown doll looks bad (critical ratio 3.68). Also a slightly higher percent of the southern children think that the brown doll has a “nice color,” while more northern children think that the white doll has a “nice color.”

In general, it may be stated that northern and southern children in these age groups tend to be similar in the degree of their preference for the white doll — with the northern children tending to be somewhat more favorable to the white doll than are the southern children. The southern children, however, in spite of their 26 equal favorableness toward the white doll, are significantly less likely to reject the brown doll (evaluate it negatively), as compared to the strong tendency for the majority of the northern, children to do so. That this difference is not primarily due to the larger number of light children found in the northern sample is indicated by more intensive analysis presented in the complete report.

Some Qualitative Data. Many of the children entered into the experimental situation with a freedom similar to that of play. They tended to verbalize freely and much of this unsolicited verbalization was relevant to the basic problems of this study.

On the whole, the rejection of the brown doll and the preference for the white doll, when explained at all, were explained in rather simple, concrete terms; for white-doll preference — “ ’cause he’s pretty” or “ ’cause he’s white”; for rejection of the brown doll — “ ’cause he’s ugly” or “ ’cause it don’t look pretty” or “ ’cause him black” or “got black on him.”

On the other hand, some of the children who were free and relaxed in the beginning of the experiment broke down and cried or became somewhat negativistic during the latter part when they were required to make self- identifications. Indeed, two children ran out of the testing room, unconsolable, convulsed in tears. This type of behavior, although not so extreme, was more prevalent in the North than in the South. The southern children who were disturbed by this aspect of the experiment generally indicated their disturbance by smiling or matter of factly attempting to escape their dilemma either by attempted humor or rationalization.

Rationalization of the rejection of the brown doll was found among both northern and southern children, however. A northern medium six-year-old justified his rejection of the brown doll by stating that “he looks bad ’cause he hasn’t got a eyelash.” A seven-year-old medium northern child justified his choice of the white doll as the doll with a “nice color” because “his feet, hands, ears, elbows, knees, and hair are clean.”

A northern five-year-old dark child felt compelled to explain his identification with the brown doll by making the following unsolicited statement: “I burned my face and made it spoil.’’ A seven-year-old northern light child went to great pains to explain that he is actually white but: “I look brown because I got a suntan in the summer.”

Condensed by the authors from an unpublished study made possible by a fellowship grant from the Julius Rosenwald Fund, 1940-1941.

*Other techniques presented in the larger study include: (1) a coloring test; (2) a questionnaire and (3) a modification of the Horowitz line drawing technique. (R. E. Horowitz, “Racial Aspects of Self-identification in Nursery School Children,” J. Psychol., 1939, VII, 91-99.)

*These results are supported by similar ones from the Horowitz line drawing technique.

*These results are supported by those from the use of the Horowitz line drawing technique.

*These results substantiate and dearly focus the trend observed through the use of the Horowitz line drawing technique.

27 Harry F. Harlow (1958)

The Nature of Love

American Psychologist, 13, 673-685

http://dx.doi.org/10.1037/h0047884

[Cited by 2913] [on Google Scholar as of SEP 13, 2017]

Word Count from MS Word (excluding references, tables, and figures)

Love is a wondrous state, deep, tender, and rewarding. Because of its intimate and personal nature it is regarded by some as an improper topic for experimental research. But, whatever our personal feelings may be, our assigned mission as psychologists is to analyze all facets of human and animal behavior into their component variables. So far as love or affection is concerned, psychologists have failed in this mission. The little we know about love does not transcend simple observation, and the little we write about it has been written better by poets and novelists. But of greater concern is the fact that psychologists tend to give progressively less attention to a motive which pervades our entire lives. Psychologists, at least psychologists who write textbooks, not only show no interest in the origin and development of love or affection, but they seem to be unaware of its very existence.

The apparent repression of love by modem psychologists stands in sharp contrast with the attitude taken by many famous and normal people. The word "love" has the highest reference frequency of any word cited in Bartlett's book of Familiar Quotations. It would appear that this emotion has long had a vast interest and fascination for human beings, regardless of the attitude taken by psychologists; but the quotations cited, even by famous and normal people, have a mundane redundancy. These authors and authorities have stolen love from the child and infant and made it the exclusive property of the adolescent and adult.

Thoughtful men, and probably all women, have speculated on the nature of love. From the developmental point of view, the general plan is quite clear: The initial love responses of the human being are those made by the infant to the mother or some mother surrogate. From this intimate attachment of the child to the mother, multiple learned and generalized affectional responses are formed. 28 Unfortunately, beyond these simple facts we know little about the fundamental variables underlying the formation of affectional responses and little about the mechanisms through which the love of the infant for the mother develops into the multifaceted response patterns characterizing love or affection in the adult. Because of the dearth of experimentation, theories about the fundamental nature of affection have evolved at the level of observation, intuition, and discerning guesswork, whether these have been proposed by psychologists, sociologists, anthropologists, physicians, or psychoanalysts.

The position commonly held by psychologists and sociologists is quite clear: The basic motives are, for the most part, the primary drives -- particularly hunger, thirst, elimination, pain, and sex -- and all other motives, including love or affection, are derived or secondary drives. The mother is associated with the reduction of the primary drives -- particularly hunger, thirst, and pain -- and through learning, affection or love is derived.

It is entirely reasonable to believe that the mother through association with food may become a secondary- reinforcing agent, but this is an inadequate mechanism to account for the persistence of the infant-maternal ties. There is a spate of researches on the formation of secondary reinforcers to hunger and thirst reduction. There can be no question that almost any external stimulus can become a secondary reinforcer if properly associated with tissue-need reduction, but the fact remains that this redundant literature demonstrates unequivocally that such derived drives suffer relatively rapid experimental extinction. Contrariwise, human affection does not extinguish when the mother ceases to have intimate association with the drives in question. Instead, the affectional ties to the mother show a lifelong, unrelenting persistence and, even more surprising, widely expanding generality.

Oddly enough, one of the few psychologists who took a position counter to modern psychological dogma was John B. Watson, who believed that love was an innate emotion elicited by cutaneous stimulation of the erogenous zones. But experimental psychologists, with their peculiar propensity to discover facts that are not true, brushed this theory aside by demonstrating that the human neonate had no differentiable emotions, and they established a fundamental psychological law that prophets are without honor in their own profession.

The psychoanalysts have concerned themselves with the problem of the nature of the development of love in the neonate and infant, using ill and aging human beings as subjects. They have discovered the overwhelming importance of the breast and related this to the oral erotic tendencies developed at an age preceding their subjects' memories. Their theories range from a belief that the infant has an innate need to achieve and suckle at the breast to beliefs not unlike commonly accepted psychological theories. There are exceptions, as seen in the recent writings of John Bowlby, who attributes importance not only to food and thirst satisfaction, but also to "primary object-clinging," a need for intimate physical contact, which is initially associated with the mother.

As far as I know, there exists no direct experimental analysis of the relative importance of the stimulus variables determining the affectional or love responses in the neonatal and infant primate. Unfortunately, the human neonate is a limited experimental subject for such researches because of his inadequate motor capabilities. By the time the human infant's motor responses can be precisely measured, the antecedent determining conditions cannot be defined, having been lost in a jumble and jungle of confounded variables.

Many of these difficulties can be resolved by the use of the neonatal and infant macaque monkey as the subject for the analysis of basic affectional variables. It is possible to make precise measurements in this primate beginning at two to ten days of age, depending upon the maturational status of the individual animal at birth. The macaque infant differs from the human infant in that the monkey is more mature at birth and grows more rapidly; but the basic responses relating to affection, including nursing, contact, clinging, and even visual and auditory exploration, exhibit no fundamental differences in the two species. Even the development of perception, fear, frustration, and learning capability follows very similar sequences in rhesus monkeys and human children.

Three years' experimentation before we started our studies on affection gave us experience with the neonatal monkey. We had separated more than 60 of these animals from their mothers 6 to 12 hours after birth and suckled them on tiny bottles. The infant mortality was only a small fraction of what would have obtained had we let the monkey mothers raise their infants. Our bottle-fed babies were healthier and heavier than monkey- mother-reared infants. We know that we are better monkey mothers than are real monkey mothers thanks to synthetic diets, vitamins, iron extracts, penicillin, chloromycetin, 5% glucose, and constant, tender, loving care. 29 During the course of these studies we noticed that the laboratory raised babies showed strong attachment to the cloth pads (folded gauze diapers) which were used to cover the hardware-cloth floors of their cages. The infants clung to these pads and engaged in violet temper tantrums when the pads were removed and replaced for sanitary reasons. Such contact-need or responsiveness had been reported previously by Gertrude van Wagenen for the monkey and by Thomas McCulloch and George Haslerud for the chimpanzee and is reminiscent of the devotion often exhibited by human infants to their pillows, blankets, and soft, cuddly stuffed toys. Responsiveness by the one-day-old infant monkey to the cloth pad is shown in Figure 1, and an unusual and strong attachment of a six-month-old infant to the cloth pad is illustrated in Figure 2. The baby, human or monkey, if it is to survive, must clutch at more than a straw.

30 We had also discovered during some allied observational studies that a baby monkey raised on a bare wire-mesh cage floor survives with difficulty, if at all, during the first five days of life. If a wire-mesh cone is introduced, the baby does better; and, if the cone is covered with terry cloth, husky, healthy, happy babies evolve. It takes more than a baby and a box to make a normal monkey. We were impressed by the possibility that, above and beyond the bubbling fountain of breast or bottle, contact comfort might be a very important variable in the development of the infant's affection for the mother.

At this point we decided to study the development of affectional responses of neonatal and infant monkeys to an artificial, inanimate mother, and so we built a surrogate mother which we hoped and believed would be a good surrogate mother. In devising this surrogate mother we were dependent neither upon the capriciousness of evolutionary processes nor upon mutations produced by chance radioactive fallout. Instead, we designed the mother surrogate in terms of modem human engineering principles (Figure 3). We produced a perfectly proportioned, streamlined body stripped of unnecessary bulges and appendices. Redundancy in the surrogate mother's system was avoided by reducing the number of breasts from two to one and placing this unibreast in an upper-thoracic, sagittal position, thus maximizing the natural and known perceptual-motor capabilities of the infant operator. The surrogate was made from a block of wood, covered with sponge rubber, and sheathed in tan cotton terry cloth. A light bulb behind her radiated heat. The result was a mother, soft, warm, and tender, a mother with infinite patience, a mother available twenty-four hours a day, a mother that never scolded her infant and never struck or bit her baby in anger. Furthermore, we designed a mother-machine with maximal maintenance efficiency since failure of any system or function could be resolved by the simple substitution of black boxes and new component parts. It is our opinion that we engineered a very superior monkey mother, although this position is not held universally by the monkey fathers. 31 Before beginning our initial experiment we also designed and constructed a second mother surrogate, a surrogate in which we deliberately built less than the maximal capability for contact comfort. This surrogate mother is illustrated in Figure 4. She is made of wire- mesh, a substance entirely adequate to provide postural support and nursing capability, and she is warmed by radiant heat. Her body differs in no essential way from that of the cloth mother surrogate other than in the quality of the contact comfort which she can supply. In our initial experiment, the dual mother- surrogate condition, a cloth mother and a wire mother were placed in different cubicles attached to the infant's living cage as shown in Figure 4. For four newborn monkeys the cloth mother lactated and the wire mother did not; and, for the other four, this condition was reversed. In either condition the infant received all its milk through the mother surrogate as soon as it was able to maintain itself in this way, a capability achieved within two or three days except in the case of very immature infants. Supplementary feedings were given until the milk intake from the mother surrogate was adequate. Thus, the experiment was designed as a test of the relative importance of the variables of contact comfort and nursing comfort. During the first 14 days of life the monkey's cage floor was covered with a heating pad wrapped in a folded gauze diaper, and thereafter the cage floor was bare. The infants were always free to leave the heating pad or cage floor to contact either mother, and the time spent on the surrogate mothers was automatically recorded. Figure 5 shows the total time spent cloth and wire mothers under the two conditions of feeding. These data make it obvious that contact comfort is a variable of overwhelming importance in the development of affectional response, whereas lactation is a variable of negligible importance. With age and opportunity to learn, subjects with the lactating wire mother showed decreasing responsiveness to her and increasing responsiveness to the nonlactating cloth mother, a finding completely contrary to any interpretation of derived drive in which the mother-form becomes conditioned to hunger-thirst reduction. The persistence of these differential responses throughout 165 consecutive days of testing is evident in Figure 6.

One control group of neonatal monkeys was raised on a single wire mother, and a second control group was raised on a single cloth mother. There were no differences between these two groups in amount of milk ingested or in weight gain. The only difference between the two groups lay in the composition of the feces, the softer stools of the wire-mother infants suggesting psychosomatic involvement. The wire mother is biologically adequate but psychologically inept.

We were not surprised to discover that contact comfort was an important basic affectional or love variable, but we did not expect it to overshadow so completely the variable of nursing; indeed; indeed, the disparity is so great as to suggest that the primary function of nursing as an affectional variable is that of insuring frequent and intimate body contact of the infant with the mother. Certainly, man cannot live by milk alone. Love is an emotion that does not need to be bottle- or spoon-fed, and we may be sure that there is nothing to be gained by giving lip service to love.

A charming lady once heard me describe these experiments and, when I subsequently talked to her, her face brightened with sudden insight: "Now I know what's wrong with me," she said, "I'm just a wire mother." Perhaps she was lucky. She might have been a wire wife.

We believe that contact comfort has long served the animal kingdom as a motivating agent for affectional responses. Since at the present time we have no experimental data to substantiate this position, we supply information which must be accepted, if at all, on the basis of face validity: 33

One function of the real mother, human or subhuman, and presumably of a mother surrogate, is to provide a haven of safety for the infant in times of fear and danger. The frightened or ailing child clings to its mother, not its father; and this selective responsiveness in times of distress, disturbance, or danger may be used as a measure of the strength of affectional bonds. We have tested this kind of differential responsiveness by presenting to the infants in their cages, in the presence of the two mothers, various fear-producing stimuli such as the moving toy bear illustrated in Figure 13. A typical response to a fear stimulus is shown in Figure 14, and the data on differential responsiveness are presented in Figure 15. It is apparent that the cloth mother is highly preferred over the wire one, and this differential selectivity is enhanced by age and experience. In this situation, the variable of nursing appears to be of absolutely no importance: the infant consistently seeks the soft mother surrogate regardless of nursing condition. 38

Similarly, the mother or mother surrogate provides its young with a source of security, and this role or function is seen with special clarity when mother and child are in a strange situation. At the present time we have completed tests for this relationship on four of our eight baby monkeys assigned to the dual mother-surrogate condition by introducing them for three minutes into the strange environment of a room measuring six feet by six feet by six feet (also called the "open-field test") and containing multiple stimuli known to elicit curiosity- manipulatory responses in baby monkeys. The subjects were placed in this situation twice a week for eight weeks with no mother surrogate present during alternate sessions and the cloth mother present during the others. A cloth diaper was always available as one of the stimuli throughout all sessions. After one or two adaptation sessions, the infants always rushed to the mother surrogate when she was present and clutched her, rubbed their bodies against her, and frequently manipulated her body and face. After a few additional sessions, the infants began to use the mother surrogate as a source of security, a base of operations. 40

As is shown in Figures 16 and 17, they would explore and manipulate a stimulus and then return to the mother before adventuring again into the strange new world. The behavior of these infants was quite different when the mother was absent from the room. Frequently they would freeze in a crouched position, as is illustrated in Figures 18 and 19. Emotionality indices such as vocalization, crouching, rocking, and sucking increased sharply, as shown in Figure 20. Total emotionality score was cut in half when the mother was present. In the absence of the mother some of the experimental monkeys would rush to the center of the room where the mother was customarily placed and then run rapidly from object to object, screaming and crying all the while. Continuous, frantic clutching of their bodies was very common, even when not in the crouching position. These monkeys frequently contacted and clutched the cloth diaper, but this action never pacified them. The same behavior occurred in the presence of the wire mother. No difference between the cloth-mother-fed and wire- mother-fed infants was demonstrated under either condition. Four control infants never raised with a mother surrogate showed the same emotionality scores when the mother was absent as the experimental infants showed in the absence of the mother, but the controls' scores were slightly larger in the presence of the mother surrogate than in her absence.

43 Some years ago Robert Butler demonstrated that mature monkeys enclosed in a dimly lighted box would open and reopen a door hour after hour for no other reward than that of looking outside the box. We now have data indicating that neonatal monkeys show this same compulsive visual curiosity on their first test day in an adaptation of the Butler apparatus which we call the "love machine," an apparatus designed to measure love. Usually these tests are begun when the monkey is 10 days of age, but this same persistent visual exploration has been obtained in a three-day- old monkey during the first half-hour of testing.

Butler also demonstrated that rhesus monkeys show selectivity in rate and frequency of door- opening to stimuli of differential attractiveness in the visual field outside the box. We have utilized this principle of response selectivity by the monkey to measure strength of affectional responsiveness in our infants in the baby version of the Butler box. The test sequence involves four repetitions of a test battery in which four stimuli -- cloth mother, wire mother, infant monkey, and empty box -- are presented for a 30-minute period on successive days.

The first four subjects in the dual mother- surrogate group were given a single test sequence at 40 to 50 days of age, depending upon the availability of the apparatus, and only their data are presented. The second set of four subjects is being given repetitive tests to obtain information relating to the development of visual exploration. The apparatus is illustrated in Figure 21. The data obtained from the first four infants raised with the two mother surrogates are presented in the middle graph of Figure 22 and show approximately equal responding to the cloth mother and another infant monkey, and no greater responsiveness to the wire mother than to an empty box. Again, the results are independent of the kind of mother that lactated, cloth or wire. The same results are found for a control group raised, but not fed, on a single cloth mother; these data appear in the graph on the right. Contrariwise, the graph on the left shows no differential responsiveness to cloth and wire mothers by a second control group, which was not raised on any mother surrogate. We can be certain that not all love is blind. 44

The first four infant monkeys in the dual mother-surrogate group were separated from their mothers between 165 and 170 days of age and tested for retention during the following 9 days and then at 30-day intervals for six successive months. Affectional retention as measured by the modified Butler box is given in Figure 23. In keeping with the data obtained on adult monkeys by Butler, we find a high rate of responding to any stimulus, even the empty box. But throughout the entire 185-day retention period there is a consistent and significant difference in response frequency to the cloth mother contrasted with either the wire mother or the empty box, and no consistent difference between wire mother and empty box.

Affectional retention was also tested in the open field during the first 9 days after separation and then at 30-day intervals, and each test condition was run twice at each retention interval. The infant's behavior differed from that observed during the period preceding separation. When the cloth mother was present in the post- separation period, the babies rushed to her, climbed up, clung tightly to her, and rubbed their heads and faces against her body. After this initial embrace and reunion, they played on the mother, including biting and tearing at her cloth cover; but they rarely made any attempt to leave her during the test period, nor did they manipulate or play with the objects in the room, in contrast with their behavior before maternal separation. The only exception was the occasional monkey that left the mother surrogate momentarily, grasped the folded piece of paper (one of the standard stimuli in the field), and brought it quickly back to the mother. It appeared that deprivation had enhanced the tie to the mother and rendered the contact-comfort need so prepotent that need for the mother overwhelmed the exploratory motives during the brief, three-minute test sessions. No change in these behaviors was observed throughout the 185-day period. When the mother was absent from the open 45 field, the behavior of the infants was similar in the initial retention test to that during the pre-separation tests; but they tended to show gradual adaptation to the open-field situation with repeated testing and, consequently, a reduction in their emotionality scores.

In the last five retention test periods, an additional test was introduced in which the surrogate mother was placed in the center of the room and covered with a clear Plexiglas box. The monkeys were initially disturbed and frustrated when their explorations and manipulations of the box failed to provide contact with the mother. However, all animals adapted to the situation rather rapidly. Soon they used the box as a place of orientation for exploratory and play behavior, made frequent contacts with the objects in the field, and very often brought these objects to the Plexiglas box. The emotionality index was slightly higher than in the condition of the available cloth mothers, but it in no way approached the emotionality level displayed when the cloth mother was absent. Obviously, the infant monkeys gained emotional security by the presence of the mother even though contact was denied.

Affectional retention has also been measured by tests in which the monkey must unfasten a three-device mechanical puzzle to obtain entrance into a compartment containing the mother surrogate. All the trials are initiated by allowing the infant to go through an unlocked door, and in half the trials it finds the mother present and in half, an empty compartment. The door is then locked and a ten-minute test conducted. In tests given prior to separation from the surrogate mothers, some of the infants had solved this puzzle and others had failed. The data of Figure 24 show that on the last test before separation there were no differences in total manipulation under mother-present and mother-absent conditions, but striking differences exist between the two conditions throughout the post-separation test periods. Again, there is no interaction with conditions of feeding.

The over-all picture obtained from surveying the retention data is unequivocal. There is little, if any, waning of responsiveness to the mother throughout this five-month period as indicated by any measure. It becomes perfectly obvious that this affectional bond is highly resistant to forgetting and that it can be retained for very long periods of time by relatively infrequent contact reinforcement. During the next year, retention tests will be conducted at 90-day intervals, and further plans are dependent upon the results obtained. It would appear that affectional responses may show as much resistance to extinction as has been previously demonstrated for learned fears and learned pain, and such data would be in keeping with those of common human observation.

The infant's responses to the mother surrogate in the fear tests, the open-field situation, and the baby Butler box and the responses on the retention tests cannot be described adequately with words. For supplementary information we turn to the motion picture record. (At this point a 20-minute film was presented illustrating and supplementing the behaviors described thus far in the address.)

We have already described the group of four control infants that had never lived in the presence of any mother surrogate and had demonstrated no sign of affection or security in the presence of the cloth mothers introduced in test sessions. When these infants reached the age of 250 days, cubicles containing both a cloth mother and a wire mother were attached to their cages. There was no lactation in these mothers, for the 46 monkeys were on a solid-food diet. The initial reaction of the monkeys to the alterations was one of extreme disturbance. All the infants screamed violently and made repeated attempts to escape the cage whenever the door was opened. They kept a maximum distance from the mother surrogates and exhibited a considerable amount of rocking and crouching behavior, indicative of emotionality. Our first thought was that the critical period for the development of maternally directed affection had passed and that these macaque children were doomed to live as affectional orphans. Fortunately, these behaviors continued for only 12 to 48 hours and then gradually ebbed, changing from indifference to active contact on, and exploration of, the surrogates. The home-cage behavior of these control monkeys slowly became similar to that of the animals raised with the mother surrogates from birth. Their manipulation and play on the cloth mother became progressively more vigorous to the point of actual mutilation, particularly during the morning after the cloth mother had been given her daily change of terry covering. The control subjects were now actively running to the cloth mother when frightened and had to be coaxed from her to be taken from the cage for formal testing.

Objective evidence of these changing behaviors is given in Figure 25, which plots the amount of time these infants spent on the mother surrogates. Within 10 days mean contact time is approximately nine hours, and this measure remains relatively constant throughout the next 30 days. Consistent with the results on the subjects reared from birth with dual mothers, these late-adopted infants spent less than one and one-half hours per day in contact with the wire mothers, and this activity level was relatively constant throughout the test sessions. Although the maximum time that the control monkeys spent on the cloth mother was only about half that Spent by the original dual mother-surrogate group, we cannot be sure that this discrepancy is a function of differential early experience. The control monkeys were about three months older when the mothers were attached to their cages than the experimental animals had been when their mothers were removed and the retention tests begun. Thus, we do not know what the amount of contact would be for a 250-day-old animal raised from birth with surrogate mothers. Nevertheless, the magnitude of the differences and the fact that the contact-time curves for the mothered-from-birth infants had remained constant for almost 150 days suggest that early experience with the mother is a variable of measurable importance.

The control group has also been tested for differential visual exploration after the introduction of the cloth and wire mothers; these behaviors are plotted in Figure 26. By the second test session a high level of exploratory behavior had developed, and the responsiveness to the wire mother and the empty box is significantly greater than that to the cloth mother. This is probably not an artifact since there is every reason to believe that the face of the cloth mother is a fear stimulus to most monkeys that have not had extensive experience with this object during the first 40 to 60 days of life. Within the third test session a sharp change in trend occurs, and the cloth mother is then more frequently viewed than the wire mother or the blank box; this trend continues during the fourth session, producing a significant preference for the cloth mother. 47

Before the introduction of the mother surrogate into the home-cage situation, only one of the four control monkeys had ever contacted the cloth mother in the open-field tests. In general, the surrogate mother not only gave the infants no security, but instead appeared to serve as a fear stimulus. The emotionality scores of these control subjects were slightly higher during the mother-present test sessions than during the mother-absent test sessions. These behaviors were changed radically by the fourth post-introduction test approximately 60 days later. In the absence of the cloth mothers the emotionality index in this fourth test remains near the earlier level, but the score is reduced by half when the mother is present, a result strikingly similar to that found for infants raised with the dual mother-surrogates from birth. The control infants now show increasing object exploration and play behavior, and they begin to use the mother as a base of operations, as did the infants raised from birth with the mother surrogates. However, there are still definite differences in the behavior of the two groups. The control infants do not rush directly to the mother and clutch her violently; but instead they go toward, and orient around, her, usually after an initial period during which they frequently show disturbed behavior, exploratory behavior, or both.

That the control monkeys develop affection or love for the cloth mother when she is introduced into the cage at 250 days of age cannot be questioned. There is every reason to believe, however, that this interval of delay depresses the intensity of the affectional response below that of the infant monkeys that were surrogate- mothered from birth onward. In interpreting these data it is well to remember that the control monkeys had had continuous opportunity to observe and hear other monkeys housed in adjacent cages and that they had had limited opportunity to view and contact surrogate mothers in the test situations, even though they did not exploit the opportunities.

During the last two years we have observed the behavior of two infants raised by their own mothers. Love for the real mother and love for the surrogate mother appear to be very similar. The baby macaque spends many hours a day clinging to its real mother. If away from the mother when frightened, it rushes to her and in her presence shows comfort and composure. As far as we can observe, the infant monkey's affection for the real mother is strong, but no stronger than that of the experimental monkey for the surrogate cloth mother, and the security that the infant gains from the presence of the real mother is no greater than the security it gains from a cloth surrogate. Next year we hope to put this problem to final, definitive, experimental test. But, whether the mother is real or a cloth surrogate, there does develop a deep and abiding bond between mother and child. In one case it may be the call of the wild and in the other the McCall of civilization, but in both cases there is "togetherness."

In spite of the importance of contact comfort, there is reason to believe that other variables of measurable importance will be discovered. Postural support may be such a variable, and it has been suggested that, when we build arms into the mother surrogate, 10 is the minimal number required to provide adequate child care. Rocking motion may be such a variable, and we are comparing rocking and stationary mother surrogates and inclined planes. The differential responsiveness to cloth mother and cloth-covered inclined plane suggests that clinging as well as contact is an affectional variable of importance. Sounds, particularly natural, maternal 48 sounds, may operate as either unlearned or learned affectional variables. Visual responsiveness may be such a variable, and it is possible that some semblance of visual imprinting may develop in the neonatal monkey. There are indications that this becomes a variable of importance during the course of infancy through some maturational process.

John Bowlby has suggested that there is an affectional variable which he calls "primary object following," characterized by visual and oral search of the mother's face. Our surrogate-mother-raised baby monkeys are at first inattentive to her face, as are human neonates to human mother faces. But by 30 days of age ever- increasing responsiveness to the mother's face appears -- whether through learning, maturation, or both -- and we have reason to believe that the face becomes an object of special attention.

Our first surrogate-mother-raised baby had a mother whose head was just a ball of wood since the baby was a month early and we had not had time to design a more esthetic head and face. This baby had contact with the blank-faced mother for 180 days and was then placed with two cloth mothers, one motionless and one rocking, both being endowed with painted, ornamented faces. To our surprise the animal would compulsively rotate both faces 180 degrees so that it viewed only a round, smooth face and never the painted, ornamented face. Furthermore, it would do this as long as the patience of the experimenter in reorienting the faces persisted. The monkey showed no sign of fear or anxiety, but it showed unlimited persistence. Subsequently it improved its technique, compulsively removing the heads and rolling them into its cage as fast as they were returned. We are intrigued by this observation, and we plan to examine systematically the role of the mother face in the development of infant-monkey affections. Indeed, these observations suggest the need for a series of ethological-type researches on the two-faced female.

Although we have made no attempts thus far to study the generalization of infant-macaque affection or love, the techniques which we have developed offer promise in this uncharted field. Beyond this, there are few if any technical difficulties in studying the affection of the actual, living mother for the child, and the techniques developed can be utilized and expanded for the analysis and developmental study of father-infant and infant- infant affection.

Since we can measure neonatal and infant affectional responses to mother surrogates, and since we know they are strong and persisting, we are in a position to assess the effects of feeding and contactual schedules; consistency and inconsistency in the mother surrogates; and early, intermediate, and late maternal deprivation. Again, we have here a family of problems of fundamental interest and theoretical importance.

If the researches completed and proposed make a contribution, I shall be grateful; but I have also given full thought to possible practical applications. The socioeconomic demands of the present and the threatened socioeconomic demands of the future have led the American woman to displace, or threaten to displace, the American man in science and industry. If this process continues, the problem of proper child-rearing practices faces us with startling clarity. It is cheering in view of this trend to realize that the American male is physically endowed with all the really essential equipment to compete with the American female on equal terms in one essential activity: the rearing of infants. We now know that women in the working classes are not needed in the home because of their primary mammalian capabilities; and it is possible that in the foreseeable future neonatal nursing will not be regarded as a necessity, but as a luxury ---to use Veblen's term -- a form of conspicuous consumption limited perhaps to the upper classes. But whatever course history may take, it is comforting to know that we are now in contact with the nature of love.

Footnote

[1] The researches reported in this paper were supported by funds supplied by Grant No. M-722, National Institutes of Health, by a grant from the Ford Foundation, and by funds received from the Graduate School of the University of Wisconsin.

49 Edward C. Tolman (1948)

Cognitive Maps in Rats and Men

The Psychological Review, 55(4), 189-208

Cited by 5685 [as of SEP 13, 2017]

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I shall devote the body of this paper to a description of experiments with rats. But I shall also attempt in a few words at the close to indicate the significance of these findings on rats for the clinical behavior of men. Most of the rat investigations, which I shall report, were carried out in the Berkeley laboratory. But I shall also include, occasionally, accounts of the behavior of non-Berkeley rats who obviously have misspent their lives in out-of- State laboratories. Furthermore, in reporting our Berkeley experiments I shall have to omit a very great many. The ones I shall talk about were carried out by graduate students (or underpaid research assistants) who, supposedly, got some of their ideas from me. And a few, though a very few, were even carried out by me myself.

Let me begin by presenting diagrams for a couple of typical mazes, an alley maze and an elevated maze. In the typical experiment a hungry rat is put at the entrance of the maze (alley or elevated), and wanders about through the various true path segments and blind alleys until he finally comes to the food box and eats. This is repeated (again in the typical experiment) one trial every 24 hours and the animal tends to make fewer and fewer errors (that is, blind-alley entrances) and to take less and less time between start and goal-box until finally he is entering no blinds at all and running in a very few seconds from start to goal. The results are usually presented in the form of average curves of blind-entrances, or of seconds from start to finish, for groups of rats.

All students agree as to the facts. They disagree, however, on theory and explanation.

(1) First, there is a school of animal psychologists which believes that the maze behavior of rats is a matter of mere simple stimulus-response connections. Learning, according to them, consists in the strengthening of some of these connections and in the weakening of others. According to this 'stimulus-response' school the rat in progressing down the maze is helplessly responding to a succession of external stimuli-sights, sounds, smells, pressures, etc. impinging upon his external sense organs-plus internal stimuli coming from the viscera 50 and from the skeletal muscles. These external and internal stimuli call out the walkings, runnings, turnings, retracings, smellings, rearings, and the like which appear. The rat's central nervous system, according to this view, may be likened to a complicated telephone switchboard.

There are the incoming calls from sense-organs and there are the outgoing messages to muscles. Before the learning of a specific maze, the connecting switches (synapses according to the physiologist) are closed in one set of ways and produce the primarily exploratory responses which appear in the early trials. Learning, according to this view, consists in the respective strengthening and weakening of various of these connections; those connections which result in the animal's going down the true path become relatively more open to the passage of nervous impulses, whereas those which lead him into the blinds become relatively less open.

It must be noted in addition, however, that this stimulus-response school divides further into two subgroups.

(a) There is a subgroup which holds that the mere mechanics involved in the running of a maze is such that the crucial stimuli from the maze get presented simultaneously with the correct responses more frequently than they do with any of the incorrect responses. Hence, just on a basis of this greater frequency, the neural connections between the crucial stimuli and the correct responses will tend, it is said, to get strengthened at the expense of the incorrect connections.

(b) There is a second subgroup in this stimulus-response school which holds that the reason the appropriate connections get strengthened relatively to the inappropriate ones is, rather, the fact that the responses resulting from the correct connections are followed more closely in time by need-reductions. Thus a hungry rat in a maze tends to get to food and have his hunger reduced sooner as a result of the true path responses than as a result of the blind alley responses. And such immediately following need-reductions or, to use another term, such 'positive reinforcements' tend somehow, it is said, to strengthen the connections which have most closely preceded them. Thus it is as if-although this is certainly not the way this subgroup would themselves state it-the satisfaction-receiving part of the rat telephoned back to Central and said to the girl: "Hold that connection; it was good; and see to it that you blankety-blank well use it again the next time these same stimuli come in."

These theorists also assume (at least some of them do some of the time) that, if bad results-'annoyances,' 'negative reinforcements'-follow, then this same satisfaction-and annoyance-receiving part of the rat will telephone back and say, "Break that connection and don't you dare use it next time either."

So much for a brief summary of the two subvarieties of the 'stimulus-response,' or telephone switchboard school.

(2) Let us turn now to the second main school. This group (and I belong to them) may be called the field theorists. We believe that in the course of learning something like a field map of the environment gets established in the rat's brain. We agree with the other school that the rat in running a maze is exposed to stimuli and is finally led as a result of these stimuli to the responses which actually occur. We feel, however, that the intervening brain processes are more complicated, more patterned and often, pragmatically speaking, more autonomous than do the stimulus-response psychologists. Although we admit that the rat is bombarded by stimuli, we hold that his nervous system is surprisingly selective as to which of these stimuli it will let in at any given time.

Secondly, we assert that the central office itself is far more like a map control room than it is like an old- fashioned telephone exchange. The stimuli, which are allowed in, are not connected by just simple one-to-one switches to the outgoing responses. Rather, the incoming impulses are usually worked over and elaborated in the central control room into a tentative, cognitive-like map of the environment. And it is this tentative map, indicating routes and paths and environmental relationships, which finally determines what responses, if any, the animal will finally release.

Finally, I, personally, would hold further that it is also important to discover in how far these maps are relatively narrow and strip-like or relatively broad and comprehensive. Both strip-maps and comprehensive-maps may be either correct or incorrect in the sense that they may (or may not), when acted upon, lead successfully to the animal's goal. The differences between such strip maps and such comprehensive maps will appear only 51 when the rat is later presented with some change within the given environment. Then, the narrower and more strip-like the original map, the less will it carry over successfully to the new problem; whereas, the wider and the more comprehensive it was, the more adequately it will serve in the new set-up. In a strip-map the given position of the animal is connected by only a relatively simple and single path to the position of the goal. In a comprehensive-map a wider arc of the environment is represented, so that, if the starting position of the animal be changed or variations in the specific routes be introduced, this wider map will allow the animal still to behave relatively correctly and to choose the appropriate new route.

But let us turn, now, to the actual experiments. The ones, out of many, which I have selected to report are simply ones which seem especially important in reinforcing the theoretical position I have been presenting. This position, I repeat, contains two assumptions: First, that learning consists not in stimulus-response connections but in the building up in the nervous system of sets which function like cognitive maps, and second, that such cognitive maps may be usefully characterized as varying from a narrow strip variety to a broader comprehensive variety.

The experiments fall under five heads: (1) "latent learning," (2) "vicarious trail and error" or "VTE," (3) "searching for the stimulus," (4) "hypotheses" and (5) "spatial orientation."

(1) "Latent Learning" Experiments. The first of the latent learning experiments was performed at Berkeley by Blodgett. It was published in 1929. Blodgett not only performed the experiments, he also originated the concept. He ran three groups of rats through a six-unit alley maze, shown in Figure 4. He had a control group and two experimental groups. The error curves for these groups appear in Figure 5. The solid line shows the error curve for Group I, the control group. These animals were run in orthodox fashion. That is, they were run one trial a day and found food in the goal-box at the end of each trial. Groups II and III were the experimental groups.

The animals of Group II, the dash line, were not fed in the maze for the first six days but only in their home cages some two hours later. On the seventh day (indicated by the small cross) the rats found food at the end of the maze for the first time and continued to find it on subsequent days. The animals of Group III were treated similarly except that they first found food at the end of the maze on the third day and continued to find it there on subsequent days. It will be observed that the experimental groups as long as they were not finding food did not appear to learn much. (Their error curves did not drop.) But on the days immediately succeeding their first finding of the food their error curves did drop astoundingly. It appeared, in short, that during the non-rewarded trials these animals had been learning much more than they had exhibited. This learning, which did not manifest itself until after the food had been introduced, Blodgett called "latent learning." Interpreting these results anthropomorphically, we would say that as long as the animals were not getting any food at the end of the maze they continued to take their time in going through it-they continued to enter many blinds. Once, however, they knew they were to get food, they demonstrated that during these preceding non-rewarded trials they had learned where many of the blinds were. They had been building up a 'map,' and could utilize the latter as soon as they were motivated to do so.

Honzik and myself repeated the experiments (or rather he did and I got some of the credit) with the 14-unit T- mazes shown in Figure 1, and with larger groups of animals, and got similar results. The resulting curves are shown in Figure 6. We used two control groups-one that never found food in the maze (HNR) and one that found it throughout (HR). The experimental group (HNR-R) found food at the end of the maze from the 11th day on and showed the same sort of a sudden drop. But probably the best experiment demonstrating latent learning was, unfortunately, done not in Berkeley but at the University of Iowa, by Spence and Lippitt. Only an abstract of this experiment has as yet been published. However, Spence has sent a preliminary manuscript from which the following account is summarized.

A simple Y-maze (see Figure 7) with two goal-boxes was used. Water was at the end of the right arm of the Y and food at the end of the left arm. During the training period the rats were run neither hungry nor thirsty. They were satiated for both food and water before each day's trials. However, they were willing to run because after each run they were taken out of whichever end box they had got to and put into a living cage, with other animals in it. They were given four trials a day in this fashion for seven days, two trials to the right and two to the left. 52 In the crucial test the animals were divided into two subgroups one made solely hungry and one solely thirsty. It was then found that on the first trial the hungry group went at once to the left, where the food had been, statistically more frequently than to the right; and the thirsty group went to the right, where the water had been, statistically more frequently than to the left. These results indicated that under the previous non-differential and very mild rewarding conditions of merely being returned to the home cages the animals had nevertheless been learning where the water was and where the food was. In short, they had acquired a cognitive map to the effect that food was to the left and water to the right, although during the acquisition of this map they had not exhibited any stimulus-response propensities to go more to the side which became later the side of the appropriate goal.

There have been numerous other latent learning experiments done in the Berkeley laboratory and elsewhere. In general, they have for the most part all confirmed the above sort of findings.

Let us turn now to the second group of experiments.

(2) "Vicarious Trial and Error" or "VTE." The term Vicarious Trial and Error (abbreviated as VTE) was invented by Prof. Muenzinger at Colorado to designate the hesitating, looking-back-and-forth, sort of behavior which rats can often be observed to indulge in at a choice-point before actually going one way or the other.

Quite a number of experiments upon VTEing have been carried out in our laboratory. I shall report only a few. In most of them what is called a discrimination set-up has been used. In one characteristic type of visual discrimination apparatus designed by Lashly (shown in Figure 8) the animal is put on a jumping stand and faced with two doors which differ in some visual property say, as here shown, vertical stripes vs. horizontal stripes.

One of each such pair of visual stimuli is made always correct and the other wrong; and the two are interchanged from side to side in random fashion. The animal is required to learn, say, that the vertically striped door is always the correct one. If he jumps to it, the door falls open and he gets to food on a platform behind. If, on the other hand, he jumps incorrectly, he finds the door locked and falls into a net some two feet below from which he is picked up and started over again.

Using a similar set-up (see Figure 9), but with landing platforms in front of the doors so that if the rat chose incorrectly he could jump back again and start over, I found that when the choice was an easy one, say between a white door and a black door, the animals not only learned sooner but also did more VTEing than when the choice was difficult, say between a white door and a gray door (see Figure 10). It appeared further (see Figure 11) that the VTEing began to appear just as (or just before) the rats began to learn. After the learning had become established, however, the VTE's began to go down. Further, in a study of individual differences by myself, Geier and Levin (actually done by Geier and Levin) using this same visual discrimination apparatus, it was found that with one and the same difficulty of problem the smarter animal did the more VTEing.

To sum up, in visual discrimination experiments the better the learning, the more the VTE's. But this seems contrary to what we would perhaps have expected. We ourselves would expect to do more VTEing, more sampling of the two stimuli, when it is difficult to choose between them than when it is easy.

What is the explanation? The answer lies, I believe, in the fact that the manner in which we set the visual discrimination problems for the rats and the manner in which we set similar problems for ourselves are different. We already have our 'instructions.' We know beforehand what it is we are to do. We are told, or we tell ourselves, that it is the lighter of the two grays, the heavier of the two weights, or the like, which is to be chosen. In such a setting we do more sampling, more VTEing, when the stimulus-difference is small. But for the rats the usual problem in a discrimination apparatus is quite different. They do not know what is wanted of them. The major part of their learning in most such experiments seems to consist in their discovering the instructions. The rats have to discover that it is the differences in visual brightness, not the differences between left and right, which they are to pay attention to. Their VTEing appears when they begin to 'catch on.' The greater the difference between the two stimuli the more the animals are attracted by this difference. Hence the sooner they catch on, and during this catching on, the more they VTE. 53 That this is a reasonable interpretation appeared further, from an experiment by myself and Minium (the actual work done, of course, by Minium) in which a group of six rats was first taught a white vs. black discrimination, then two successively more difficult gray vs. black discriminations. For each difficulty the rats were given a long series of further trials beyond the points at which they had learned. Comparing the beginning of each of these three difficulties the results were that the rats did more VTEing for the easy discriminations than for the more difficult ones. When, however, it came to a comparison of amounts of VTEing during the final performance after each learning had reached a plateau, the opposite results were obtained. In other words, after the rats had finally divined their instructions, then they, like human beings, did more VTEing, more sampling, the more difficult the discrimination.

Finally, now let us note that is was also found at Berkeley by Jackson that in a maze the difficult maze units produce more VTEing and also that the more stupid rats do the more VTEing. The explanation, as I see it, is that, in the case of mazes, rats know their instructions. For them it is natural to expect that the same spatial path will always lead to the same outcome. Rats in mazes don't have to be told.

But what, now, is the final significance of all this VTEing? How do these facts about VTEing affect our theoretical argument? My answer is that these facts lend further support to the doctrine of a building up of maps. VTEing, as I see it, is evidence that in the critical stages-whether in the first picking up of the instructions or in the later making sure of which stimulus is which-the animal's activity is not just one of responding passively to discrete stimuli, but rather one of the active selecting and comparing of stimuli. The brings me then to the third type of experiment.

(3) "Searching for the Stimulus." I refer to a recent, and it seems to me extremely important experiment, done for a Ph.D. dissertation by Hudson. Hudson was first interested in the question of whether or not rats could learn an avoidance reaction in one trial. His animals were tested one at a time in a living cage (see Figure 13) with a small striped visual pattern at the end, on which was mounted a food cup. The hungry rat approached this food cup and ate. An electrical arrangement was provided so that when the rat touched the cup he could be given an electric shock. And one such shock did appear to be enough. For when the rat was replaced in this same cage days or even weeks afterwards, he usually demonstrated immediately strong avoidance reactions to the visual pattern. The animal withdrew from that end of the cage, or piled up sawdust and covered the pattern, or showed various other amusing responses all of which were in the nature of withdrawing from the pattern or making it disappear.

But the particular finding which I am interested in now appeared as a result of a modification of this standard procedure. Hudson noticed that the animals, anthropomorphically speaking, often seemed to look around after the shock to see what it was that had hit them. Hence it occurred to him that, if the pattern were made to disappear the instant the shock occurred, the rats might not establish the association. And this indeed is what happened in the case of many individuals. Hudson added further electrical connections so that when the shock was received during the eating, the lights went out, the pattern and the food cup dropped out of sight, and the lights came on again all within the matter of a second. When such animals were again put in the cage 24 hours later, a large percentage showed no avoidance of the pattern. Or to quote Hudson's own words:

"Learning what object to avoid...may occur exclusively during the period after the shock. For if the object from which the shock was actually received is removed at the moment of the shock, a significant number of animals fail to learn to avoid it, some selecting other features in the environment for avoidance, and others avoiding nothing."

In other words, I feel that this experiment reinforces the notion of the largely active selective character in the rat's building up of his cognitive map. He often has to look actively for the significant stimuli in order to form his map and does not merely passively receive and react to all the stimuli which are physically present.

Turn now to the fourth type of experiment.

(4) The "Hypothesis" Experiments. Both the notion of hypotheses in rats and the design of the experiments to demonstrate such hypotheses are to be credited to Krech. Krech used a four-compartment discrimination-box. In such a four-choice box the correct door at each choice-point may be determined by the experimenter in terms of its being lighted or dark, left or right, or various combinations of these. If all possibilities are 54 randomized for the 40 choices made in 10 runs of each day's test, the problem could be made insoluble.

When this was done, Krech found that the individual rat went through a succession of systematic choices. That is, the individual animal might perhaps begin by choosing practically all right-handed doors, then he might give this up for choosing practically all left-hand doors, and then, for choosing all dark doors, and so on. These relatively persistent, and well-above-chance systematic types of choice Krech called "hypotheses." In using this term he obviously did not mean to imply verbal processes in the rat but merely referred to what I have been calling cognitive maps which, it appears from his experiments, get set up in a tentative fashion to be tried out first one and then another until, if possible, one is found which works.

Finally, it is to be noted that these hypothesis experiments, like the latent learning, VTE, and "looking for the stimulus" experiments, do not, as such, throw light upon the widths of the maps which are picked up but do indicate the generally map-like and self-initiated character of learning.

For the beginning of an attack upon the problem of the width of the maps let me turn to the last group of experiments.

(5) "Spatial Orientation" Experiments. As early as 1929, Lashley reported incidentally the case of a couple of his rats who, after having learned an alley maze, pushed back the cover near the starting box, climbed out and ran directly across the top to the goal-box where they climbed down in again and ate. Other investigators have reported related findings. All such observations suggest that rats really develop wider spatial maps which include more than the mere trained-on specific paths. In the experiments now to be reported this possibility has been subjected to further examination.

In the first experiment, Tolman, Ritchie and Kalish (actually Ritchie and Kalish) used the set-up shown in Figure 15.

This was an elevated maze. The animals ran from A across the open circular table through CD (which had alley walls) and finally to G, the food box. H was a light which shone directly down the path from G to F. After four nights, three trials per night, in which the rats learned to run directly and without hesitation from A to G, the apparatus was changed to the sun-burst shown in Figure 16. The starting path and the table remained the same but a series of radiating paths was added.

The animals were again started at A and ran across the circular table into the alley and found themselves blocked. They then returned onto the table and began exploring practically all the radiating paths. After going out a few inches only on any one path, each rat finally chose to run all the way out on one. The percentages of rats finally choosing each of the long paths from 1 to 12 are shown in Figure 17. It appears that there was a preponderant tendency to choose path No.6 which ran to a point some four inches in front of where the entrance to the food-box had been. The only other path chosen with any appreciable frequency was No.1-that is, the path which pointed perpendicularly to the food-side of the room.

These results seem to indicate that the rats in this experiment had learned not only to run rapidly down the original roundabout route but also, when this was blocked and radiating paths presented, to select one pointing rather directly towards the point where the food had been or else at least to select a path running perpendicularly to the food-side of the room.

As a result of their original training, the rats had, it would seem, acquired not merely a strip-map to the effect that the original specifically trained-on path led to food but, rather, a wider comprehensive map to the effect that food was located in such and such a direction in the room.

Consider now a further experiment done by Ritchie alone. This experiment tested still further the breadth of the spatial map which is acquired. In this further experiment the rats were again run across the table-this time to the arms of a simple T.

Twenty-five animals were trained for seven days, 20 trials in all, to find food at F1; and twenty-five animals were trained to find it at F2. The L's in the diagram indicate lights. On the eighth day the starting path and table top were rotated through 180 degrees so that they were now in the position shown in Figure 19. The dottted 55 lines represent the old position. And a series of radiating paths was added. What happened? Again the rats ran across the table into the central alley. When, however, they found themselves blocked, they turned back onto the table and this time also spent many seconds touching and trying out for only a few steps practically all the paths. Finally, however, within seven minutes, 42 of the 50 rats chose one path and ran all the way out on it. The paths finally chosen by the 19 of these animals that had been fed at F1 and by the 23 that had been fed at F2 are shown in Figure 20.

This time the rats tended to choose, not the paths which pointed directly to the spots where the food had been, but rather paths which ran perpendicularly to the corresponding sides of the room. The spatial maps of these rats, when the animals were started from the opposite side of the room, were thus not completely adequate to the precise goal positions but were adequate as to the correct sides of the room. The maps of these animals were, in short, not altogether strip-like and narrow.

This completes my report of experiments. There were the latent learning experiments, the VTE experiments, the searching for the stimulus experiment, the hypothesis experiments, and these last spatial orientation experiments.

And now, at last, I come to the humanly significant and exciting problem: namely, what are the conditions which favor narrow strip-maps and what are those which tend to favor broad comprehensive maps not only in rats but also in men?

There is considerable evidence scattered throughout the literature bearing on this question both for rats and for men. Some of this evidence was obtained in Berkeley and some of it elsewhere. I have not time to present it in any detail. I can merely summarize it by saying that narrow strip maps rather than broad comprehensive maps seem to be induced: (1) by a damaged brain, (2) by an inadequate array of environmentally presented cues, (3) by an overdose of repetitions on the original trained-on path and (4) by the presence of too strongly motivational or of too strongly frustrating conditions.

It is this fourth factor which I wish to elaborate upon briefly in my concluding remarks. For it is going to be my contention that some, at least, of the so-called 'psychological mechanisms' which the clinical psychologists and the other students of personality have uncovered as the devils underlying many of our individual and social malajustments can be interpreted as narrowings of our cognitive maps due to too strong motivations or to too intense frustration.

My argument will be brief, cavalier, and dogmatic. For I am not myself a clinician or a social psychologist. What I am going to say must be considered, therefore, simply as in the nature of a rat psychologist's ratiocinations offered free.

By way of illustration, let me suggest that at least the three dynamisms called, respectively, "regression," "fixation," and "displacement of aggression onto outgroups" are expressions of cognitive maps which are too narrow and which get built up in us as a result of too violent motivation or of too intense frustration.

(a) Consider regression. This is the term used for those cases in which an individual, in the face of too difficult a problem, returns to earlier more childish ways of behaving. Thus, to take an example, the overprotected middle-aged woman (reported a couple of years ago in Time Magazine) who, after losing her husband, regressed (much to the distress of her growing daughters) into dressing in too youthful a fashion and into competing for their beaux and then finally into behaving like a child requiring continuous care, would be an illustration of regression. I would not wish you to put too much confidence in the reportorial accuracy of Time, but such an extreme case is not too different from many actually to be found in our mental hospitals or even sometimes in ourselves. In all such instances my argument would be (1) that such regression results from too strong a present emotional situation and (2) that it consists in going back to too narrow an earlier map, itself due to too much frustration or motivation in early childhood. Time's middle-aged woman was presented by too frustrating an emotional situation at her husband's death and she regressed, I would wager, to too narrow adolescent and childhood maps since these latter had been originally excessively impressed because of overstressful experiences at the time she was growing up.

(b) Consider fixation. Regression and fixation tend to go hand in hand. For another way of stating the fact of 56 the undue persistence of early maps is to say that they were fixated. This has even been demonstrated in rats. If rats are too strongly motivated in their original learning, they find it very difficult to relearn when the original path is no longer correct. Also after they have relearned, if they are given an electric shock they, like Time's woman, tend to regress back again to choosing the earlier path.

(c) Finally, consider the "displacement of aggression onto outgroups." Adherence to one's own group is an ever-present tendency among primates. It is found in chimpanzees and monkeys as strongly as in men. We primates operate in groups. And each individual in such a group tends to identify with his whole group in the sense that the group's goal's become his goals, the group's life and immortality, his life and immortality. Furthermore, each individual soon learns that, when as an individual he is frustrated, he must not take out his aggressions on the other members of his own group. He learns instead to displace his aggressions onto outgroups. Such a displacement of aggression I would claim is also a narrowing of the cognitive map. The individual comes no longer to distinguish the true locus of the cause of his frustration. The poor Southern whites, who take it out on the Negroes, are displacing their aggressions from the landlords, the southern economic system, the northern capitalists, or wherever the true cause of their frustration may lie, onto a mere convenient outgroup. The physicists on the Faculty who criticize the humanities, or we psychologists who criticize all the other departments, or the University as a whole which criticizes the Secondary School system or, vice versa, the Secondary School system which criticizes the University-or, on a still larger and far more dangerous scene-we Americans who criticize the Russians and the Russians who criticize us, are also engaging, at least in part, in nothing more than such irrational displacements of our aggressions onto outgroups.

I do not mean to imply that there may not be some true interferences by the one group with the goals of the other and hence that the aggressions of the members of the one group against the members of the other are necessarily wholly and merely displaced aggressions. But I do assert that often and in large part they are such mere displacements.

Over and over again men are blinded by too violent motivations and too intense frustrations into blind and unintelligent and in the end desperately dangerous hates of outsiders. And the expression of these their displaced hates ranges all the way from discrimination against minorities to world conflagrations.

What is the name of Heaven and Psychology can we do about it? My only answer is to preach again the virtues of reason-of, that is, broad cognitive maps. And to suggest that the child-trainers and the world- planners of the future can only, if at all, bring about the presence of the required rationality (i.e., comprehensive maps) if they see to it that nobody's children are too over-motivated or too frustrated. Only then can these children learn to look before and after, learn to see that there are often round-about and safer paths to their quite proper goals-learn, that is, to realize that the well-beings of White and of Negro, of Catholic and of Protestant, of Christian and of Jew, of American and of Russian (and even of males and females) are mutually interdependent.

We dare not let ourselves or others become so over-emotional, so hungry, so ill-clad, so over-motivated that only narrow strip-maps will be developed. All of us in Europe as well as in America, in the Orient as well as in the Occident, must be made calm enough and well-fed enough to be able to develop truly comprehensive maps, or, as Freud would have put it, to be able to learn to live according to the Reality Principle rather than according to the too narrow and too immediate Pleasure Principle.

We must, in short, subject our children and ourselves (as the kindly experimenter would his rats) to the optimal conditions of moderate motivation and of an absence of unnecessary frustrations, whenever we put them and ourselves before that great God-given maze which is our human world. I cannot predict whether or not we will be able, or be allowed, to do this; but I can say that, only insofar as we are able and are allowed, have we cause for hope.

57 George A. Miller (1956)

The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information

Psychological Review, 63(2), 81-97

[Cited by 26424 as of SEP 13, 2017]

Word Count from MS Word (excluding references, tables, and figures)

My problem is that I have been persecuted by an integer. For seven years this number has followed me around, has intruded in my most private data, and has assaulted me from the pages of our most public journals. This number assumes a variety of disguises, being sometimes a little larger and sometimes a little smaller than usual, but never changing so much as to be unrecognizable. The persistence with which this number plagues me is far more than a random accident. There is, to quote a famous senator, a design behind it, some pattern governing its appearances. Either there really is something unusual about the number or else I am suffering from delusions of persecution.

I shall begin my case history by telling you about some experiments that tested how accurately people can assign numbers to the magnitudes of various aspects of a stimulus. In the traditional language of psychology these would be called experiments in absolute judgment. Historical accident, however, has decreed that they should have another name. We now call them experiments on the capacity of people to transmit information. Since these experiments would not have been done without the appearance of information theory on the psychological scene, and since the results are analyzed in terms of the concepts of information theory, I shall have to preface my discussion with a few remarks about this theory.

Information Measurement

The "amount of information" is exactly the same concept that we have talked about for years under the name of "variance." The equations are different, but if we hold tight to the idea that anything that increases the variance also increases the amount of information we cannot go far astray.

The advantages of this new way of talking about variance are simple enough. Variance is always stated in terms of the unit of measurement–inches, pounds, volts, etc.–whereas the amount of information is a 58 dimensionless quantity. Since the information in a discrete statistical distribution does not depend upon the unit of measurement, we can extend the concept to situations where we have no metric and we would not ordinarily think of using the variance. And it also enables us to compare results obtained in quite different experimental situations where it would be meaningless to compare variances based on different metrics. So there are some good reasons for adopting the newer concept.

The similarity of variance and amount of information might be explained this way: When we have a large variance, we are very ignorant about what is going to happen. If we are very ignorant, then when we make the observation it gives us a lot of information. On the other hand, if the variance is very small, we know in advance how our observation must come out, so we get little information from making the observation.

If you will now imagine a communication system, you will realize that there is a great deal of variability about what goes into the system and also a great deal of variability about what comes out. The input and the output can therefore be described in terms of their variance (or their information). If it is a good communication system, however, there must be some systematic relation between what goes in and what comes out. That is to say, the output will depend upon the input, or will be correlated with the input. If we measure this correlation, then we can say how much of the output variance is attributable to the input and how much is due to random fluctuations or "noise" introduced by the system during transmission. So we see that the measure of transmitted information is simply a measure of the input-output correlation.

There are two simple rules to follow. Whenever I refer to "amount of information," you will understand "variance." And whenever I refer to "amount of transmitted information," you will understand "covariance" or "correlation."

The situation can be described graphically by two partially overlapping circles. Then the left circle can be taken to represent the variance of the input, the right circle the variance of the output, and the overlap the covariance of input and output. I shall speak of the left circle as the amount of input information, the right circle as the amount of output information, and the overlap as the amount of transmitted information.

In the experiments on absolute judgment, the observer is considered to be a communication channel. Then the left circle would represent the amount of information in the stimuli, the right circle the amount of information in his responses, and the overlap the stimulus-response correlation as measured by the amount of transmitted information. The experimental problem is to increase the amount of input information and to measure the amount of transmitted information. If the observer's absolute judgments are quite accurate, then nearly all of the input information will be transmitted and will be recoverable from his responses. If he makes errors, then the transmitted information may be considerably less than the input. We expect that, as we increase the amount of input information, the observer will begin to make more and more errors: we can test the limits of accuracy of his absolute judgments. If the human observer is a reasonable kind of communication system, then when we increase the amount of input information the transmitted information will increase at first and will eventually level off at some asymptotic value. This asymptotic value we take to be the channel capacity of the observer: it represents the greatest amount of information that he can give us about the stimulus on the basis of an absolute judgment. The channel capacity is the upper limit on the extent to which the observer can match his responses to the stimuli we give him.

Now just a brief word about the bit and we can begin to look at some data. One bit of information is the amount of information that we need to make a decision between two equally likely alternatives. If we must decide whether a man is less than six feet tall or more than six feet tall and if we know that the chances are 50—50, then we need one bit of information. Notice that this unit of information does not refer in any way to the unit of length that we use–feet, inches, centimeters, etc. However you measure the man's height, we still need just one bit of information.

Two bits of information enable us to decide among four equally likely alternatives. Three bits of information enable us to decide among eight equally likely alternatives. Four bits of information decide among 16 alternatives, five among 32, and so on. That is to say, if there are 32 equally likely alternatives, we must make five successive binary decisions, worth one bit each, before we know which alternative is correct. So the general rule is simple: every time the number of alternatives is increased by a factor of two, one bit of information is added. 59 There are two ways we might increase the amount of input information. We could increase the rate at which we give information to the observer, so that the amount of information per unit time would increase. Or we could ignore the time variable completely and increase the amount of input information by increasing the number of alternative stimuli. In the absolute judgment experiment we are interested in the second alternative. We give the observer as much time as he wants to make his response; we simply increase the number of alternative stimuli among which he must discriminate and look to see where confusions begin to occur. Confusions will appear near the point that we are calling his "channel capacity."

Absolute Judgments of Unidimensional Stimuli

Now let us consider what happens when we make absolute judgments of tones. Pollack (17) asked listeners to identify tones by assigning numerals to them. The tones were different with respect to frequency, and covered the range from 100 to 8000 cps in equal logarithmic steps. A tone was sounded and the listener responded by giving a numeral. After the listener had made his response he was told the correct identification of the tone.

When only two or three tones were used the listeners never confused them. With four different tones confusions were quite rare, but with five or more tones confusions were frequent. With fourteen different tones the listeners made many mistakes.

These data are plotted in Figure 1. Along the bottom is the amount of input information in bits per stimulus. As the number of alternative tones was increased from 2 to 14, the input information increased from 1 to 3.8 bits. On the ordinate is plotted the amount of transmitted information. The amount of transmitted information behaves in much the way we would expect a communication channel to behave; the transmitted information increases linearly up to about 2 bits and then bends off toward an asymptote at about 2.5 bits. This value, 2.5 bits, therefore, is what we are calling the channel capacity of the listener for absolute judgments of pitch.

So now we have the number 2.5 bits. What does it mean? First, note that 2.5 bits corresponds to about six equally likely alternatives. The result means that we cannot pick more than six different pitches that the listener will never confuse. Or, stated slightly differently, no matter how many alternative tones we ask him to judge, the best we can expect him to do is to assign them to about six different classes without error. Or, again, if we know that there were N alternative stimuli, then his judgment enables us to narrow down the particular stimulus to one out of N /6.

Most people are surprised that the number is as small as six. Of course, there is evidence that a musically sophisticated person with absolute pitch can identify accurately any one of 50 or 60 different pitches. Fortunately, I do not have time to discuss these remarkable exceptions. I say it is fortunate because I do not know how to explain their superior performance. So I shall stick to the more pedestrian fact that most of us can identify about one out of only five or six pitches before we begin to get confused.

It is interesting to consider that psychologists have been using seven-point rating scales for a long time, on the intuitive basis that trying to rate into finer categories does not really add much to the usefulness of the ratings. Pollack's results indicate that, at least for pitches, this intuition is fairly sound.

Next you can ask how reproducible this result is. Does it depend on the spacing of the tones or the various conditions of judgment? Pollack varied these conditions in a number of ways. The range of frequencies can be changed by a factor of about 20 without changing the amount of information transmuted more than a small percentage. Different groupings of the pitches decreased the transmission, but the loss was small. For example, if you can discriminate five high-pitched tones in one series and five low-pitched tones in another series, it is reasonable to expect that you could combine all ten into a single series and still tell them all apart without error. When you try it, however, it does not work. The channel capacity for pitch seems to be about six and that is the best you can do.

While we are on tones, let us look next at Garner's (7) work on loudness. Garner's data for loudness are summarized in Figure 2. Garner went to some trouble to get the best possible spacing of his tones over the intensity range from 15 to 110 db. He used 4, 5, 6, 7, 10, and 20 different stimulus intensities. The results shown in Figure 2 take into account the differences among subjects and the sequential influence of the 60 immediately preceding judgment. Again we find that there seems to be a limit. The channel capacity for absolute judgments of loudness is 2.3 bits, or about five perfectly discriminable alternatives.

Since these two studies were done in different laboratories with slightly different techniques and methods of analysis, we are not in a good position to argue whether five loudnesses is significantly different from six pitches. Probably the difference is in the right direction, and absolute judgments of pitch are slightly more accurate than absolute judgments of loudness. The important point, however, is that the two answers are of the same order of magnitude.

The experiment has also been done for taste intensities. In Figure 3 are the results obtained by Beebe-Center, Rogers, and O'Connell (1) for absolute judgments of the concentration of salt solutions. The concentrations ranged from 0.3 to 34.7 gm. NaCl per 100 cc. tap water in equal subjective steps. They used 3, 5, 9, and 17 different concentrations. The channel capacity is 1.9 bits, which is about four distinct concentrations. Thus taste intensities seem a little less distinctive than auditory stimuli, but again the order of magnitude is not far off.

On the other hand, the channel capacity for judgments of visual position seems to be significantly larger. Hake and Garner (8) asked observers to interpolate visually between two scale markers. Their results are shown in Figure 4. They did the experiment in two ways. In one version they let the observer use any number between zero and 100 to describe the position, although they presented stimuli at only 5, 10, 20,or 50 different positions. The results with this unlimited response technique are shown by the filled circles on the graph. In the other version the observers were limited in their responses to reporting just those stimulus values that were possible. That is to say, in the second version the number of different responses that the observer could make was exactly the same as the number of different stimuli that the experimenter might present. The results with this limited response technique are shown by the open circles on the graph. The two functions are so similar that it seems fair to conclude that the number of responses available to the observer had nothing to do with the channel capacity of 3.25 bits.

The Hake-Garner experiment has been repeated by Coonan and Klemmer. Although they have not yet published their results, they have given me permission to say that they obtained channel capacities ranging from 3.2 bits for very short exposures of the pointer position to 3.9 bits for longer exposures. These values are slightly higher than Hake and Garner's, so we must conclude that there are between 10 and 15 distinct positions along a linear interval. This is the largest channel capacity that has been measured for any unidimensional variable.

At the present time these four experiments on absolute judgments of simple, unidimensional stimuli are all that have appeared in the psychological journals. However, a great deal of work on other stimulus variables has not yet appeared in the journals. For example, Eriksen and Hake (6) have found that the channel capacity for judging the sizes of squares is 2.2 bits, or about five categories, under a wide range of experimental conditions. In a separate experiment Eriksen (5) found 2.8 bits for size, 3.1 bits for hue, and 2.3 bits for brightness. Geldard has measured the channel capacity for the skin by placing vibrators on the chest region. A good observer can identify about four intensities, about five durations, and about seven locations.

One of the most active groups in this area has been the Air Force Operational Applications Laboratory. Pollack has been kind enough to furnish me with the results of their measurements for several aspects of visual displays. They made measurements for area and for the curvature, length, and direction of lines. In one set of experiments they used a very short exposure of the stimulus–1/40 second–and then they repeated the measurements with a 5-second exposure. For area they got 2.6 bits with the short exposure and 2.7 bits with the long exposure. For the length of a line they got about 2.6 bits with the short exposure and about 3.0 bits with the long exposure. Direction, or angle of inclination, gave 2.8 bits for the short exposure and 3.3 bits for the long exposure. Curvature was apparently harder to judge. When the length of the arc was constant, the result at the short exposure duration was 2.2 bits, but when the length of the chord was constant, the result was only 1.6 bits. This last value is the lowest that anyone has measured to date. I should add, however, that these values are apt to be slightly too low because the data from all subjects were pooled before the transmitted information was computed. 61 Now let us see where we are. First, the channel capacity does seem to be a valid notion for describing human observers. Second, the channel capacities measured for these unidimensional variables range from 1.6 bits for curvature to 3.9 bits for positions in an interval. Although there is no question that the differences among the variables are real and meaningful, the more impressive fact to me is their considerable similarity. If I take the best estimates I can get of the channel capacities for all the stimulus variables I have mentioned, the mean is 2.6 bits and the standard deviation is only 0.6 bit. In terms of distinguishable alternatives, this mean corresponds to about 6.5 categories, one standard deviation includes from 4 to 10 categories, and the total range is from 3 to 15 categories. Considering the wide variety of different variables that have been studied, I find this to be a remarkably narrow range.

There seems to be some limitation built into us either by learning or by the design of our nervous systems, a limit that keeps our channel capacities in this general range. On the basis of the present evidence it seems safe to say that we possess a finite and rather small capacity for making such unidimensional judgments and that this capacity does not vary a great deal from one simple sensory attribute to another.

Absolute Judgments of Multidimensional Stimuli

You may have noticed that I have been careful to say that this magical number seven applies to one- dimensional judgments. Everyday experience teaches us that we can identify accurately any one of several hundred faces, any one of several thousand words, any one of several thousand objects, etc. The story certainly would not be complete if we stopped at this point. We must have some understanding of why the one- dimensional variables we judge in the laboratory give results so far out of line with what we do constantly in our behavior outside the laboratory. A possible explanation lies in the number of independently variable attributes of the stimuli that are being judged. Objects, faces, words, and the like differ from one another in many ways, whereas the simple stimuli we have considered thus far differ from one another in only one respect.

Fortunately, there are a few data on what happens when we make absolute judgments of stimuli that differ from one another in several ways. Let us look first at the results Klemmer and Frick (13) have reported for the absolute judgment of the position of a dot in a square. In Figure 5 we see their results. Now the channel capacity seems to have increased to 4.6 bits, which means that people can identify accurately any one of 24 positions in the square.

The position of a dot in a square is clearly a two-dimensional proposition. Both its horizontal and its vertical position must be identified. Thus it seems natural to compare the 4.6-bit capacity for a square with the 3.25-bit capacity for the position of a point in an interval. The point in the square requires two judgments of the interval type. If we have a capacity of 3.25 bits for estimating intervals and we do this twice, we should get 6.5 bits as our capacity for locating points in a square. Adding the second independent dimension gives us an increase from 3.25 to 4.6, but it falls short of the perfect addition that would give 6.5 bits.

Another example is provided by Beebe-Center, Rogers, and O'Connell. When they asked people to identify both the saltiness and the sweetness of solutions containing various concentrations of salt and sucrose, they found that the channel capacity was 2.3 bits. Since the capacity for salt alone was 1.9, we might expect about 3.8 bits if the two aspects of the compound stimuli were judged independently. As with spatial locations, the second dimension adds a little to the capacity but not as much as it conceivably might.

A third example is provided by Pollack (18), who asked listeners to judge both the loudness and the pitch of pure tones. Since pitch gives 2.5 bits and loudness gives 2.3 bits, we might hope to get as much as 4.8 bits for pitch and loudness together. Pollack obtained 3.1 bits, which again indicates that the second dimension augments the channel capacity but not so much as it might.

A fourth example can be drawn from the work of Halsey and Chapanis (9) on confusions among colors of equal luminance. Although they did not analyze their results in informational terms, they estimate that there are about 11 to 15 identifiable colors, or, in our terms, about 3.6 bits. Since these colors varied in both hue and saturation, it is probably correct to regard this as a two-dimensional judgment. If we compare this with Eriksen's 3.1 bits for hue (which is a questionable comparison to draw), we again have something less than perfect addition when a second dimension is added. 62 It is still a long way, however, from these two-dimensional examples to the multidimensional stimuli provided by faces, words, etc. To fill this gap we have only one experiment, an auditory study done by Pollack and Ficks (19). They managed to get six different acoustic variables that they could change: frequency, intensity, rate of interruption, on-time fraction, total duration, and spatial location. Each one of these six variables could assume any one of five different values, so altogether there were 5 6 , or 15,625 different tones that they could present. The listeners made a separate rating for each one of these six dimensions. Under these conditions the transmitted information was 7.2 bits, which corresponds to about 150 different categories that could be absolutely identified without error. Now we are beginning to get up into the range that ordinary experience would lead us to expect.

Suppose that we plot these data, fragmentary as they are, and make a guess about how the channel capacity changes with the dimensionality of the stimuli. The result is given in Figure 6. In a moment of considerable daring I sketched the dotted line to indicate roughly the trend that the data seemed to be taking.

Clearly, the addition of independently variable attributes to the stimulus increases the channel capacity, but at a decreasing rate. It is interesting to note that the channel capacity is increased even when the several variables are not independent. Eriksen (5) reports that, when size, brightness, and hue all vary together in perfect correlation, the transmitted information is 4.1 bits as compared with an average of about 2.7 bits when these attributes are varied one at a time. By confounding three attributes, Eriksen increased the dimensionality of the input without increasing the amount of input information; the result was an increase in channel capacity of about the amount that the dotted function in Figure 6 would lead us to expect.

The point seems to be that, as we add more variables to the display, we increase the total capacity, but we decrease the accuracy for any particular variable. In other words, we can make relatively crude judgments of several things simultaneously.

We might argue that in the course of evolution those organisms were most successful that were responsive to the widest range of stimulus energies in their environment. In order to survive in a constantly fluctuating world, it was better to have a little information about a lot of things than to have a lot of information about a small segment of the environment. If a compromise was necessary, the one we seem to have made is clearly the more adaptive.

Pollack and Ficks's results are very strongly suggestive of an argument that linguists and phoneticians have been making for some time (11). According to the linguistic analysis of the sounds of human speech, there are about eight or ten dimensions–the linguists call them distinctive features –that distinguish one phoneme from another. These distinctive features are usually binary, or at most ternary, in nature. For example, a binary distinction is made between vowels and consonants, a binary decision is made between oral and nasal consonants, a ternary decision is made among front, middle, and back phonemes, etc. This approach gives us quite a different picture of speech perception than we might otherwise obtain from our studies of the speech spectrum and of the ear's ability to discriminate relative differences among pure tones. I am personally much interested in this new approach (15) , and I regret that there is not time to discuss it here.

It was probably with this linguistic theory in mind that Pollack and Ficks conducted a test on a set of tonal stimuli that varied in eight dimensions, but required only a binary decision on each dimension. With these tones they measured the transmitted information at 6.9 bits, or about 120 recognizable kinds of sounds. It is an intriguing question, as yet unexplored, whether one can go on adding dimensions indefinitely in this way.

In human speech there is clearly a limit to the number of dimensions that we use. In this instance, however, it is not known whether the limit is imposed by the nature of the perceptual machinery that must recognize the sounds or by the nature of the speech machinery that must produce them. Somebody will have to do the experiment to find out. There is a limit, however, at about eight or nine distinctive features in every language that has been studied, and so when we talk we must resort to still another trick for increasing our channel capacity. Language uses sequences of phonemes, so we make several judgments successively when we listen to words and sentences. That is to say, we use both simultaneous and successive discriminations in order to expand the rather rigid limits imposed by the inaccuracy of our absolute judgments of simple magnitudes. 63 These multidimensional judgments are strongly reminiscent of the abstraction experiment of Külpe (14). As you may remember, Külpe showed that observers report more accurately on an attribute for which they are set than on attributes for which they are not set. For example, Chapman (4) used three different attributes and compared the results obtained when the observers were instructed before the tachistoscopic presentation with the results obtained when they were not told until after the presentation which one of the three attributes was to be reported. When the instruction was given in advance, the judgments were more accurate. When the instruction was given afterwards, the subjects presumably had to judge all three attributes in order to report on any one of them and the accuracy was correspondingly lower. This is in complete accord with the results we have just been considering, where the accuracy of judgment on each attribute decreased as more dimensions were added. The point is probably obvious, but I shall make it any-how, that the abstraction experiments did not demonstrate that people can judge only one attribute at a time. They merely showed what seems quite reasonable, that people are less accurate if they must judge more than one attribute simultaneously....

The Span of Immediate Memory

Let me summarize the situation in this way. There is a clear and definite limit to the accuracy with which we can identify absolutely the magnitude of a unidimensional stimulus variable. I would propose to call this limit the span of absolute judgment, and I maintain that for unidimensional judgments this span is usually somewhere in the neighborhood of seven. We are not completely at the mercy of this limited span, however, because we have a variety of techniques for getting around it and increasing the accuracy of our judgments. The three most important of these devices are ( a ) to make relative rather than absolute judgments; or, if that is not possible, ( b ) to increase the number of dimensions along which the stimuli can differ; or ( c ) to arrange the task in such a way that we make a sequence of several absolute judgments in a row.

The study of relative judgments is one of the oldest topics in experimental psychology, and I will not pause to review it now. The second device, increasing the dimensionality, we have just considered. It seems that by adding more dimensions and requiring crude, binary, yes—no judgments on each attribute we can extend the span of absolute judgment from seven to at least 150. Judging from our everyday behavior, the limit is probably in the thousands, if indeed there is a limit. In my opinion, we cannot go on compounding dimensions indefinitely. I suspect that there is also a span of perceptual dimensionality and that this span is somewhere in the neighborhood of ten, but I must add at once that there is no objective evidence to support this suspicion. This is a question sadly needing experimental exploration.

Concerning the third device, the use of successive judgments, I have quite a bit to say because this device introduces memory as the handmaiden of discrimination. And, since mnemonic processes are at least as complex as are perceptual processes, we can anticipate that their interactions will not be easily disentangled.

Suppose that we start by simply extending slightly the experimental procedure that we have been using. Up to this point we have presented a single stimulus and asked the observer to name it immediately thereafter. We can extend this procedure by requiring the observer to withhold his response until we have given him several stimuli in succession. At the end of the sequence of stimuli he then makes his response. We still have the same sort of input-output situation that is required for the measurement of transmitted information. But now we have passed from an experiment on absolute judgment to what is traditionally called an experiment on immediate memory.

Before we look at any data on this topic I feel I must give you a word of warning to help you avoid some obvious associations that can be confusing. Everybody knows that there is a finite span of immediate memory and that for a lot of different kinds of test materials this span is about seven items in length. I have just shown you that there is a span of absolute judgment that can distinguish about seven categories and that there is a span of attention that will encompass about six objects at a glance. What is more natural than to think that all three of these spans are different aspects of a single underlying process? And that is a fundamental mistake, as I shall be at some pains to demonstrate. This mistake is one of the malicious persecutions that the magical number seven has subjected me to.

My mistake went something like this. We have seen that the invariant feature in the span of absolute judgment is the amount of information that the observer can transmit. There is a real operational similarity between the absolute judgment experiment and the immediate memory experiment. If immediate memory is like absolute 64 judgment, then it should follow that the invariant feature in the span of immediate memory is also the amount of information that an observer can retain. If the amount of information in the span of immediate memory is a constant, then the span should be short when the individual items contain a lot of information and the span should be long when the items contain little information. For example, decimal digits are worth 3.3 bits apiece. We can recall about seven of them, for a total of 23 bits of information. Isolated English words are worth about 10 bits apiece. If the total amount of information is to remain constant at 23 bits, then we should be able to remember only two or three words chosen at random. In this way I generated a theory about how the span of immediate memory should vary as a function of the amount of information per item in the test materials.

The measurements of memory span in the literature are suggestive on this question, but not definitive. And so it was necessary to do the experiment to see. Hayes (10) tried it out with five different kinds of test materials: binary digits, decimal digits, letters of the alphabet, letters plus decimal digits, and with 1,000 monosyllabic words. The lists were read aloud at the rate of one item per second and the subjects had as much time as they needed to give their responses. A procedure described by Woodworth (20) was used to score the responses.

The results are shown by the filled circles in Figure 7. Here the dotted line indicates what the span should have been if the amount of information in the span were constant. The solid curves represent the data. Hayes repeated the experiment using test vocabularies of different sizes but all containing only English monosyllables (open circles in Figure 7 ). This more homogeneous test material did not change the picture significantly. With binary items the span is about nine and, although it drops to about five with http://spider.apa.org/ftdocs/rev/1994/april/rev1012343.html (9 of 17) [10/10/2001 10:23:08 AM] monosyllabic English words, the difference is far less than the hypothesis of constant information would require.

There is nothing wrong with Hayes's experiment, because Pollack (16) repeated it much more elaborately and got essentially the same result. Pollack took pains to measure the amount of information transmitted and did not rely on the traditional procedure for scoring the responses. His results are plotted in Figure 8. Here it is clear that the amount of information transmitted is not a constant, but increases almost linearly as the amount of information per item in the input is increased.

And so the outcome is perfectly clear. In spite of the coincidence that the magical number seven appears in both places, the span of absolute judgment and the span of immediate memory are quite different kinds of limitations that are imposed on our ability to process information. Absolute judgment is limited by the amount of information. Immediate memory is limited by the number of items. In order to capture this distinction in somewhat picturesque terms, I have fallen into the custom of distinguishing between bits of information and chunks of information. Then I can say that the number of bits of information is constant for absolute judgment and the number of chunks of information is constant for immediate memory. The span of immediate memory seems to be almost independent of the number of bits per chunk, at least over the range that has been examined to date.

The contrast of the terms bit and chunk also serves to highlight the fact that we are not very definite about what constitutes a chunk of information. For example, the memory span of five words that Hayes obtained when each word was drawn at random from a set of 1000 English monosyllables might just as appropriately have been called a memory span of 15 phonemes, since each word had about three phonemes in it. Intuitively, it is clear that the subjects were recalling five words, not 15 phonemes, but the logical distinction is not immediately apparent. We are dealing here with a process of organizing or grouping the input into familiar units or chunks, and a great deal of learning has gone into the formation of these familiar units.

Recoding

In order to speak more precisely, therefore, we must recognize the importance of grouping or organizing the input sequence into units or chunks. Since the memory span is a fixed number of chunks, we can increase the number of bits of information that it contains simply by building larger and larger chunks, each chunk containing more information than before.

A man just beginning to learn radiotelegraphic code hears each dit and dah as a separate chunk. Soon he is able to organize these sounds into letters and then he can deal with the letters as chunks. Then the letters organize themselves as words, which are still larger chunks, and he begins to hear whole phrases. I do not 65 mean that each step is a discrete process, or that plateaus must appear in his learning curve, for surely the levels of organization are achieved at different rates and overlap each other during the learning process. I am simply pointing to the obvious fact that the dits and dahs are organized by learning into patterns and that as these larger chunks emerge the amount of message that the operator can remember increases correspondingly. In the terms I am proposing to use, the operator learns to increase the bits per chunk.

In the jargon of communication theory, this process would be called recoding. The input is given in a code that contains many chunks with few bits per chunk. The operator recodes the input into another code that contains fewer chunks with more bits per chunk. There are many ways to do this recoding, but probably the simplest is to group the input events, apply a new name to the group, and then remember the new name rather than the original input events.

Since I am convinced that this process is a very general and important one for psychology, I want to tell you about a demonstration experiment that should make perfectly explicit what I am talking about. This experiment was conducted by Sidney Smith and was reported by him before the Eastern Psychological Association in 1954.

Begin with the observed fact that people can repeat back eight decimal digits, but only nine binary digits. Since there is a large discrepancy in the amount of information recalled in these two cases, we suspect at once that a recoding procedure could be used to increase the span of immediate memory for binary digits. In Table 1 a method for grouping and renaming is illustrated. Along the top is a sequence of 18 binary digits, far more than any subject was able to recall after a single presentation. In the next line these same binary digits are grouped by pairs. Four possible pairs can occur: 00 is renamed 0, 01 is renamed 1, 10 is renamed 2, and 11 is renamed 3. That is to say, we recode from a base-two arithmetic to a base-four arithmetic. In the recoded sequence there are now just nine digits to remember, and this is almost within the span of immediate memory. In the next line the same sequence of binary digits is regrouped into chunks of three. There are eight possible sequences of three, so we give each sequence a new name between 0 and 7. Now we have recoded from a sequence of 18 binary digits into a sequence of 6 octal digits, and this is well within the span of immediate memory. In the last two lines the binary digits are grouped by fours and by fives and are given decimal-digit names from 0 to 15 and from 0 to 31.

It is reasonably obvious that this kind of recoding increases the bits per chunk, and packages the binary sequence into a form that can be retained within the span of immediate memory. So Smith assembled 20 subjects and measured their spans for binary and octal digits. The spans were 9 for binaries and 7 for octals. Then he gave each recoding scheme to five of the subjects. They studied the recoding until they said they understood it–for about 5 or 10 minutes. Then he tested their span for binary digits again while they tried to use the recoding schemes they had studied.

The recoding schemes increased their span for binary digits in every case. But the increase was not as large as we had expected on the basis of their span for octal digits. Since the discrepancy increased as the recoding ratio increased, we reasoned that the few minutes the subjects had spent learning the recoding schemes had not been sufficient. Apparently the translation from one code to the other must be almost automatic or the subject will lose part of the next group while he is trying to remember the translation of the last group.

Since the 4:1 and 5:1 ratios require considerable study, Smith decided to imitate Ebbinghaus and do the experiment on himself. With Germanic patience he drilled himself on each recoding successively, and obtained the results shown in Figure 9. Here the data follow along rather nicely with the results you would predict on the basis of his span for octal digits. He could remember 12 octal digits. With the 2:1 recoding, these 12 chunks were worth 24 binary digits. With the 3:1 recoding they were worth 36 binary digits. With the 4:1 and 5:1 recodings, they were worth about 40 binary digits.

It is a little dramatic to watch a person get 40 binary digits in a row and then repeat them back without error. However, if you think of this merely as a mnemonic trick for extending the memory span, you will miss the more important point that is implicit in nearly all such mnemonic devices. The point is that recoding is an extremely powerful weapon for increasing the amount of information that we can deal with. In one form or another we use recoding constantly in our daily behavior. 66 In my opinion the most customary kind of recoding that we do all the time is to translate into a verbal code. When there is a story or an argument or an idea that we want to remember, we usually try to rephrase it "in our own words." When we witness some event we want to remember, we make a verbal description of the event and then remember our verbalization. Upon recall we recreate by secondary elaboration the details that seem consistent with the particular verbal recoding we happen to have made. The well-known experiment by Carmichael, Hogan, and Walter (3) on the influence that names have on the recall of visual figures is one demonstration of the process.

The inaccuracy of the testimony of eyewitnesses is well known in legal psychology, but the distortions of testimony are not random–they follow naturally from the particular recoding that the witness used, and the particular recoding he used depends upon his whole life history. Our language is tremendously useful for repackaging material into a few chunks rich in information. I suspect that imagery is a form of recoding, too, but images seem much harder to get at operationally and to study experimentally than the more symbolic kinds of recoding.

It seems probable that even memorization can be studied in these terms. The process of memorizing may be simply the formation of chunks, or groups of items that go together, until there are few enough chunks so that we can recall all the items. The work by Bousfield and Cohen (2) on the occurrence of clustering in the recall of words is especially interesting in this respect.

Summary

I have come to the end of the data that I wanted to present, so I would like now to make some summarizing remarks.

First, the span of absolute judgment and the span of immediate memory impose severe limitations on the amount of information that we are able to receive, process, and remember. By organizing the stimulus input simultaneously into several dimensions and successively into a sequence of chunks, we manage to break (or at least stretch) this informational bottleneck.

Second, the process of recoding is a very important one in human psychology and deserves much more explicit attention than it has received. In particular, the kind of linguistic recoding that people do seems to me to be the very lifeblood of the thought processes. Recoding procedures are a constant concern to clinicians, social psychologists, linguists, and anthropologists and yet, probably because recoding is less accessible to experimental manipulation than nonsense syllables or T mazes, the traditional experimental psychologist has contributed little or nothing to their analysis. Nevertheless, experimental techniques can be used, methods of recoding can be specified, behavioral indicants can be found. And I anticipate that we will find a very orderly set of relations describing what now seems an uncharted wilderness of individual differences.

Third, the concepts and measures provided by the theory of information provide a quantitative way of getting at some of these questions. The theory provides us with a yardstick for calibrating our stimulus materials and for measuring the performance of our subjects. In the interests of communication I have suppressed the technical details of information measurement and have tried to express the ideas in more familiar terms; I hope this paraphrase will not lead you to think they are not useful in research.

Informational concepts have already proved valuable in the study of discrimination and of language; they promise a great deal in the study of learning and memory; and it has even been proposed that they can be useful in the study of concept formation. A lot of questions that seemed fruitless twenty or thirty years ago may now be worth another look. In fact, I feel that my story here must stop just as it begins to get really interesting.

And finally, what about the magical number seven? What about the seven wonders of the world, the seven seas, the seven deadly sins, the seven daughters of Atlas in the Pleiades, the seven ages of man, the seven levels of hell, the seven primary colors, the seven notes of the musical scale, and the seven days of the week? What about the seven-point rating scale, the seven categories for absolute judgment, the seven objects in the span of attention, and the seven digits in the span of immediate memory? For the present I propose to withhold judgment. Perhaps there is something deep and profound behind all these sevens, something just calling out for us to discover it. But I suspect that it is only a pernicious, Pythagorean coincidence.