Reading Rotated Words

Asher Koriat and Joel Norman University of Haifa, Haifa, Israel

Hebrew-speaking students performed lexical decisions on Hebrew letter strings that appeared at different orientations. Response times evidenced a strong interaction between string length and orientation. At angular deviations of less than 60° from the upright, neither orientation nor string length had any effect, suggesting that words were directly, and probably holistically, recognized. The results for the 60° deviation, while also exhibiting no effects of word length, yielded slower response times, suggesting a holistic rectification process. For deviations between 60° and 120°, the effects of disorientation increased sharply with increasing string length, suggesting piecemeal processing that may be due to the utilization of reading units smaller than the whole word or to piecemeal rectification. In this region, stimulus disorientation appears to impair word recognition by disrupting transgraphemic information rather than by interfering with letter identification. Extreme disorientations, 120° or more, exhibited no further impairment with increased disorientation, and all evidenced strong and similar length effects, suggesting letter-by-letter reading. The implications of the results for the reading of normal and transformed text are discussed.

This study combined a mental rotation integral whole with all its parts rotating si- task with a reading task in an attempt to multaneously around the same point or is address two separate but related issues. First, rotated segment by segment. If mental rota- is the rectification of disoriented stimuli car- tion is piecemeal and serial, the effect of ried out holistically or in a piecemeal fashion? disorientation might be expected to increase Second, are words read letter by letter or as with the complexity of the figure or the whole units? In a previous study (Koriat & number of "parts" it contains. Studies of this Norman, 1984) we asked subjects to perform issue have yielded somewhat equivocal results, a lexical decision task on five-letter rotated the majority leaning toward the nonholistic strings. Response times increased systemati- position (Cooper, 1975; Cooper & Podgorny, cally with angular deviation from the upright, 1976; Hochberg & Gellman, 1977; Pylyshyn, suggesting that words might be mentally ro- 1979; Yuile & Steiger, 1982). More recently, tated in a manner similar to that of other however, Robertson and Palmer (1983) ob- stimuli. In the present study we varied the tained data consistent with the hypothesis of number of letters in a string and examined holistic mental rotation. They used large the combined effects of degree of rotation (global) letters constructed from spatial ar- and string length on performance. rangements of small (local) letters. Rate of The issue of holism in mental rotation has mental rotation was not affected by the num- recently received a great deal of attention (see ber of levels that were rotated, suggesting a Robertson & Palmer, 1983; Shepard & holistic rotation process in which rotation of Cooper, 1982). The question is whether a global and local levels occurs together. misoriented figure is mentally rotated as an In their recent reassessment of the holistic- nonholistic issue in mental rotation, Shepard and Cooper (1982) offered a view that appears We gratefully acknowledge the assistance of Edna Ben- to accommodate the divergent results. Mental Zvi, Ofra Ziv, Abraham Papo, and Zvia Kaplan. We also rotation is assumed to be holistic when the thank William Epstein, Raymond Klein, David Navon, task involves only one stimulus that is to be and two anonymous reviewers for their helpful comments compared to a memory representation and on an earlier draft of this article. when this stimulus constitutes a well-learned, Requests for reprints should be sent to Asher Koriat, Department of Psychology, University of Haifa, Haifa integrated figure. On the other hand, mental 31999, Israel. rotation might be piecemeal when the task

490 READING ROTATED WORDS 491

calls for the matching of two stimuli, and/or word recognition is based on whole-word when the stimulus lacks mental integration. units and that disorientation disrupts the When the recognition of misoriented words total configuration of the word. A second is examined within this framework, the fol- possibility is that word recognition does rest lowing might be proposed. If familiar words on letter identities and that when letters are constitute well-integrated wholes, they should embedded in a letter string, disorientation be mentally transformed as integral units. does impair their identities or the perception Thus, the magnitude of the rotation effect of their arrangement. The study of the com- should be the same for words of different bined effects of word rotation and string length. On the other hand, if they are repre- length on word recognition might shed some sented as composites of distinct units, they light on this issue. We know that for upright might exhibit piecemeal rotation, with "rate words lexical decision latency is generally of mental rotation" decreasing with number indifferent to word length (Frederiksen & of letters in the string. Kroll, 1976), suggesting the possibility of This leads directly to the second issue, that whole-word reading. If word recognition is of holism in word recognition (see e.g., Hen- found to be indifferent to string length derson, 1980). This issue has a far longer throughout the entire range of orientations, history than the issue of holism in mental this would further substantiate the idea that rotation (e.g., Cattell, 1886; Huey, 1908) and words are generally processed as integral units. has attracted a vast amount of research effort There is some indication, however, that (see e.g., Henderson, 1982, for a review). The visual transformations that apparently do not question is whether word recognition is based disrupt letter identities do yield increased on the visual configuration of the word as a length effects relative to standard format whole or is mediated by processes of letter (Bruder, 1978: Navon, 1978). We may, there- identification. One experimental approach to fore, suspect that the effect of string length this question has involved the use of nonstan- should increase with increased disorientation, dard typographic variations, particularly those suggesting that some piecemeal sequential assumed to disrupt the familiar visual config- processing occurs. If such is the case, the uration of the word without destroying the detailed examination of the manner in which identity or the arrangement of its constituent length effects emerge with increased disori- letters (e.g., Adams, 1979). Such orthographic entation might provide some insight into the variations have been found to impair perfor- question of holism in word recognition. Thus, mance (e.g., Coltheart & Freeman, 1974), in our previous study small deviations from suggesting that word recognition normally the upright appeared to have little effects on capitalizes on supraletter features (but this word recognition. Perhaps, word length effects may also be due to the impairment of letter can be found only for those disorientations identification, see e.g., Paap, Newsome, & large enough to disrupt direct activation of Noel, 1984). On the other hand, these varia- whole-word codes. tions did not reduce the size of the word The following four experiments all involved superiority effect (McClelland, 1976), consis- lexical decisions for letter strings presented tent with letter-mediated models of reading at different angular disorientations. In the (e.g., McClelland & Rumelhart, 1981). first experiment the length of the letter strings The rotation of word stimuli utilized in was varied systematically, with the aim of the present study is another form of visual determining how the effects of disorientation distortion that has the advantage of allowing might interact with those of string length in examination of continuously graded degrees affecting performance. of transformation. In the previous study we found degree of disorientation to exert strong Experiment 1 and systematic effects on word recognition Method (Koriat & Norman, 1984). This effect is not easy to interpret, particularly because disori- Subjects. Twenty-four volunteers participated in the entation does not seem to affect the latency study. They were all students at the University of Haifa whose primary language was Hebrew. of identifying single letters (e.g., Corballis & Stimulus materials. Ninety-six Hebrew words were Nagourney, 1978). One possibility is that compiled, 24 of each of the 2-, 3-, 4-, and 5-letter lengths. 492 ASHER KORIAT AND JOEL NORMAN

They contained only consonantal letters and had only string remained in view until the subjects responded, and one pronunciation when unpointed (see Koriat, 1984). it was replaced by the subsequent stimulus after 500 ms. Twelve words of each length were transformed into String orientations were preprogrammed so that for each nonwords by replacing one letter with another consonantal subject and repetition two words and two nonwords of letter. The order of the letter strings was the same for all each length appeared at each orientation, and for each subjects. This order was random except for the constraint repetition each string appeared equally often at each that each block of eight successive strings included one orientation across all subjects. The orientation of each word and one nonword of each length. letter string varied between repetitions. Apparatus and procedure. The experiment was con- trolled by a PDF 11/34 minicomputer, and the stimuli were presented on a VT-11 CRT Graphic Display Unit. Results The subjects sat at a viewing distance of 80 cm, with their heads resting on a chin-and-head rest, preventing Response times in excess of 5,000 ms or head rotations. They were asked to classify letter strings less than 250 ms (0.8%) were eliminated from as words or nonwords as quickly as they could without making errors. They responded by pressing one key the analyses. The two repetitions yielded very labeled word with their right index finger or a second key similar results and were therefore combined. labeled nonword with their left index linger. They were Mean latencies for correct responses are informed that the strings would appear in one of six shown in Figure 1, where the effects of angular orientations. The session began with 32 practice trials, followed by two repetitions of the 96 experimental strings disorientation are seen to vary systematically in the same order. There was a 2-min break between the with string length. These results were analyzed two presentations. in terms of the four angular deviations from All strings appeared unpointed (see Koriat, 1984) at upright, 0°, 60°, 120°, and 180°, (i.e., col- the center of the screen and were rotated about their lapsing over equivalent deviations, 60° + center. The letter strings subtended 0.8 cm vertically (when upright) and ranged between 2 cm {two-letter 300°, 120° + 240°). A three-way analysis of strings) and 5 cm (five-letter strings) horizontally. Each variance (ANOVA), Angular Deviation X String

WORDS NONWORDS/

. 2 LETTERS

- 3 LETTERS

. 4 LETTERS

- 5 LETTERS

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Figure 1. Response time (in milliseconds) for words and nonwords as a function of orientation with string length as a parameter (Experiment 1). READING ROTATED WORDS 493

2000 WORDS NONWORDS

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STRING LENGTH Figure 2. Response time (in milliseconds) for words and nonwords as a function of string length for different angular deviations from the upright (Experiment 1).

Length X Lexicality (words vs. nonwords) on Interestingly, the results for the 60° devia- response times yielded significant main effects tion for words exhibit the same independence for angular deviation, F(3, 69) = 86.05, p < of length as found for the 0° orientation, but .0001, and for string length, F(3, 69) = 86.43, at the same time yield longer response times p < .0001. Response times were longer for by about 85 ms. A two-way ANOVA, 0° versus nonwords than for words, F(l, 23) = 75.43, 60° X String Length yielded a significant ef- p < .0001, and nonwords exhibited stronger fect for the 0° versus 60° comparison, F(l, effects of deviation, F(3, 69) = 3.69, p < .02, 23) = I1.16,p< .0005, but neither the effects as well as stronger effects of length, F(3, 69) = of length nor the interaction was significant. 3.81, p < .02, compared with words. This appears not to be the case for nonwords, The interaction between deviation and where the 60° deviation yielded a signifi- string length was highly significant, F(9, cant effect of string length, F(3, 69) = 6.56; 207) = 28.06, p < .0001. The nature of this p < .001. interaction may be best seen in Figure 2. For A three-way ANOVA on the error rates both words and nonwords the effect of string yielded significant main effects for angular length increases substantially with increased deviation, F(3, 69) = 3.24, p < .05, and for deviation from the upright. Normally oriented string length, F(3, 69) = 12.42, p < .0001, words (0°) show no effect of word length but no effects for lexicality. Although the (F < 1), consistent with previous findings, effects of deviation mimic those of the re- whereas for the 120° and 180° deviations sponse times, those for string length do not. response times increased by about 700 ms Mean percent errors for string lengths 2, 3, from two-letter to five-letter words, F(3, 69) = 4, and 5, were 15.1%, 11.4%, 8.4%, and 9.6%, 63.45, p < .0001. respectively. The higher error rates for the 494 ASHER KORIAT AND JOEL NORMAN

shorter strings point to the possibility of a Cooper and Shepard (1973), using reflection speed-accuracy trade-off for the length effects. decisions on single characters, found a non- linear increase in response time with degree Discussion of disorientation, with smaller disorientations yielding relatively small effects. They sug- In Experiment 1 we examined the question gested that the memory representation of the whether in reading disoriented words the normal, upright character may be broadly transformation process is holistic, operating tuned so that a response can be made for on the entire word pattern as an integral tilts of 60° or more without any need for unit, or is conducted piecewise, with segments mental rotation. This concept of broad tuning of the word transformed in turn. On the face is similar to the idea of a perceptual upright of it, the results seem to suggest the operation but appears better fitted to accommodate of both types of transformation processes. findings of a small increase in response time First, response latency increases sharply with with increasing disorientation like that found string length. The extent of orientation effects in the present study. from 0° to 180°, calculated across words and As a final comment, it should be noted nonwords, was 339 ms, 508 ms, 909 ms, and that the results appear dichotomous, with the 1,100 ms for two- to five-letter strings, re- three smaller disorientations (0°, 60°, and spectively. This systematic increase suggests 300°) yielding relatively fast responses and that whatever transformation is applied to the three larger disorientations (120°, 180°, disoriented strings, it operates in a piecemeal, and 240°) yielding considerably slower re- apparently letter-by-letter, fashion. Second, sponses that are quite similar in their mag- however, there is a range of orientations over nitude. We shall return to this point in which words seem to be processed as integral connection with Experiment 3. wholes, and when transformation is required, it operates on the word as a single unit. This Experiment 2 is suggested by the results for word stimuli at deviations 0° and 60°. Although the 60° The results of Experiment 1 can be inter- disorientation required significantly longer preted as indicating that letter strings at response times than did the upright (0°) disorientations greater than 60° tend to be orientation, this effect was independent of processed nonholistically. This interpretation word length. Apparently for deviations of up rests on the assumption that the critical factor to 40° or 60° from the upright, holistic affecting speed of processing is the number transformation processes take place. of letters in the string. The increase in response time from 0° to There are, however, two additional inter- 60° deviations is relatively slight. A similar pretations. The first is that longer strings are type of relative indifference to small disori- visually more complex, and complex figures entations from the upright has been discussed might require slower rotation rates than do by Hock and Tromley (1978) in terms of the simple figures. This account is hard to refute, notion of a perceptual upright. They proposed though it does not seem likely in view of the that each stimulus has a characteristic range fact that word length did not have any effects of orientations over which it is perceived as at the 0° and 60° deviations. If complexity upright and that mental rotation need proceed were the critical factor, it would have been only until the stimulus attains its perceptual expected to affect performance at all orien- uprightness. It is tempting to speculate that tations. The second account involves another words are perceptually upright in a range of factor that is correlated with string length, ±60° about their normal orientation, and namely, the visual extent of the stimulus. It within this range they are processed holisti- might be argued that longer strings are rotated cally. But, on the other hand, it remains more slowly than shorter strings simply be- unclear why the 60° deviations yield signifi- cause they are larger. Indeed, Shwartz (1979; cantly longer response times than do the 0° see Kosslyn, 1980, pp. 290-292) found the deviations. size of a visual image to affect rotation rate. READING ROTATED WORDS 495

Subjects were presented with an Attneave- responses for words and nonwords as a func- type polygon and were asked to rotate its tion of orientation and string length. The image until it reached a specified orientation effect of disorientation on response time is and to press a button when the desired ori- clearly stronger for four-letter strings than for entation was attained. Larger polygons were three-letter strings. A three-way ANOVA yielded found to yield slower rotation rates than significant main effects for string length, F(\, smaller polygons. 11) = 99.87, p < .0001; for orientation, F(5, In Experiment 2 we varied number of 55) = 31.77, p < .0001; and for-lexicality, letters in a string while holding its visual F(\, 11) = 53.23, p < .0001. The orientation extent constant. The stimuli were three- and effects were larger for the four-letter strings four-letter strings that subtended the same than for the three-letter strings, F(5, 55) = visual angle. If the two string lengths exhibit 12.27, p < .0001, and larger for nonwords similar effects of rotation, the results obtained than words, F(5, 55) = 4.22, p < .002. The in Experiment 1 might be interpreted in other interactions were not significant. terms of the size effect of Shwartz (1979), When the results were analyzed in terms namely that the slower "rate of rotation" of angular deviation from the upright, mean obtained for longer strings stems from a response times for 0°, 60°, 120°, and 180° slower but holistic rotation process, rather deviations were 690 ms, 735 ms, 1,125 ms, than from a nonholistic, piecemeal process. and 1,125 ms for three-letter words and 725 ms, 789 ms, 1,378 ms, and 1,426 ms for Method four-letter words, respectively. Percent errors for these four deviations were 1.4%, 2.8%, Subjects. Twelve Univeisity of Haifa students partic- 6.6%, and 7.6% for the three-letter words, ipated in the study for course credit. None had participated in Experiment 1. and 0.7%, 0.3%, 10.1%, and 6.9% for the Stimulus materials. Seventy-two three-letter and 72 four-letter words. four-letter Hebrew words were compiled, containing only It is interesting to note that, as in Experi- consonantal letters and possessing only one pronunciation. ment 1, although words at 60° deviations Half of the words of each length were transformed into nonwords by replacing one letter by another consonantal yielded significantly longer response times letter. Strings of both lengths subtended 4.3 cm horizon- than at the 0° deviation, F(l, 11) = 25.63, tally (when upright) and 1.4 cm vertically. In the three- p < .0005, the interaction between this com- letter strings letters subtended 1.3 cm maximally with parison and word length was not significant about 0.2 cm between letters. The respective values for the four-letter strings were 1.0 and O.I cm. Hebrew (F < 1). The same was true for nonwords: readers judged the two types of strings to be equally The 0° versus 60° comparison yielded F(l, similar to normal printed Hebrew. 11) = 7.08, p < .05, but the interaction was Apparatus and procedure. The apparatus and general not significant, F(l, 11) = 1.65. procedure were the same as in Experiment 1. Each All in all, the results of Experiment 2 subject was presented with four blocks, each block ho- mogeneous with respect to string length. Half the subjects indicated significantly larger orientation effects received the four blocks in the order three-, four-, four-, for the four-letter strings than for the three- and three-letter strings, and the other half in the order letter strings even when they subtended the four-, three-, three-, and four-letter strings. Each block same visual angle. included 72 experimental trials preceded by 12 practice trials. The third and fourth blocks were replications of the second and first blocks, but the string orders were Experiment 3 different, randomly determined for each subject and for each block. In each block six words and six nonwords Taken together, the results of Experiments appeared in each of the six orientations—0°, 60°, 120°, 1 and 2 indicate stronger orientation effects 180°, 240°, and, 300°—and each string appeared equally for longer letter strings, and the critical factor often in each orientation across all subjects. is the number of the letters in the string rather than its visual extent. These results Results and Discussion suggest nonholistic processing beyond 60° Responses in excess of 5,000 ms or less angular deviation from the upright. than 250 ms were discarded (0.3%). Figure 3 Experiment 3 was designed to obtain a presents mean response times for correct more fine-grained picture of the combined 496 ASHER KORIAT AND JOEL NORMAN effects of angular disorientation and string ment 1 suggest the following trends that length by sampling a larger number of ori- deserve detailed examination. First, there ap- entations. Specifically, the results of Experi- pears to be a range of orientations over which

O 3 LETTERS

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Figure 3. Response time (in milliseconds) as a function of orientation for three- and four-letter words and nonwords (Experiment 2). READING ROTATED WORDS 497 words are processed and transformed holis- each letter string varied between repetitions. tically, as suggested by the length-independent The order of the stimuli was randomly deter- increase in response time from 0° to 60° mined for each subject and for each repetition. deviations. In Experiment 3 we hope to de- limit the boundaries of this range of orien- Results tations. Second, the results for words (Figure 2) suggest a sharp dichotomy between the 0° Response latencies in excess of 5,000 ms and 60° deviations, which evidence no length and less than 250 ms were discarded (0.3%). effects at all, and the 120° and 180° devia- The two repetitions yielded similar results tions, which evidence strong and nearly iden- and were therefore combined. tical length effects. The inclusion of inter- First, we shall examine in some detail the mediate deviations might help determine main effects of rotation, after which we shall whether the transition between these two turn to the combined effects of orientation regions is sharp or gradual. Third, the com- and string length. The curves for strings of parison between the 180° and the 120° de- different lengths were all quite similar in viations suggests that beyond a certain degree shape, and Figure 4, which presents response of disorientation there is no further decrement times and percent errors averaged across string in performance and no further increase in lengths, seems to best convey the major trends. the size of the length effect with increasing One noteworthy feature of the curves pre- angular deviation. In order to examine these sented in Figure 4 is their noticeable departure trends, 18 different orientations were em- from linearity. Although response time gen- ployed in Experiment 3, 0° to 340° in 20° erally increases with angular deviation from steps, yielding a total of 10 different deviations the upright, the shapes of the functions are from the upright. different from those obtained for mental ro- Subjects. Eighteen students at the Univer- tation of block figures (Shepard & Metzler, sity of Haifa, whose primary language was 1971) or single letters (Cooper & Shepard, Hebrew, took part in the experiment for 1973) and are not consistent with the notion course credit. None had participated in Ex- of a constant rate of mental rotation. In periments 1 or 2. terms of angular deviation from the upright Stimulus materials. Two hundred and (regardless of direction), the curves appear to eighty-eight 2- to 5-letter Hebrew strings were be S-shaped, with the range between the 60° used. These represented an equal number of and 120° accounting for the bulk of the words and nonwords of each of the four rotation effect. Outside this range, that is, for lengths. The selection of words and the con- disorientations of less than 60° or more than struction of nonwords were according to the 120°, response time is relatively indifferent same criteria as used in Experiment 1. to the extent of angular deviation. Apparatus and procedure. The apparatus In the lower range, 0°, 20°, and 40° devia- was the same as in Experiment 1. The pro- tions, rotation appears to have little effect, cedure was also the same except for the with rotation effects emerging at around 60°. following. The strings appeared in 18 different Comparing only the five orientations between orientations, 0° to 340° in 20° steps. The ±40°, a one-way ANOVA yielded F < 1 for session began with 36 practice trials, followed words and F(4, 68) = 1.70, ns, for nonwords. by two repetitions of the 288 experimental These results are consistent with the notion strings. There was a short break after each of a perceptual upright and suggest that words block of 144 trials and a 2-min break between that are disoriented up to about ±40" need the two repetitions. Each block began with not be mentally rotated or rectified before four filler items to allow warm-up. String recognition. orientations were preprogrammed so that for The upper range of disorientations, 120°- each subject and repetition two words and 240°, represents perhaps the largest departure two nonwords of each length appeared at from what is customarily found for single- each orientation, and for each repetition each letter mental rotation tasks. Response times string appeared equally often at each orien- for the 180° orientation are far lower than tation across all subjects. The orientation of would have been expected. In fact, further 498 ASHER KORIAT AND JOEL NORMAN increases in angular deviation beyond 120° sponse time from 0° to 180° was 550 ms for do not result in any additional impairment words and 800 ms for nonwords, t(\7) = in performance. 4.63, p < .001. This is consistent with the Three additional features deserve mention: results of Experiment I (see Figure 1) and the word-nonword differences, the asymmetry might suggest that the transformation and effects, and the upside-down effect, all previ- recognition processes partly interact. ously noted by Koriat and Norman (1984). Second, the curves for both words and First, nonwords exhibited stronger rotation nonwords exhibit a certain degree of asym- effects than did words: The increase in re- metry that is most evident in the upper range

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Figure 4. Response time (in milliseconds) and percent errors as a function of orientation for words and nonwords (Experiment 3). READING ROTATED WORDS 499 of disorientations. Performance on the 120° one, it is not clear that the same processes orientation is considerably poorer than that are involved. on the 240° orientation, both being of equal Third, note the relative ease of processing angular disparity from the upright, t(\l) = upside-down words in comparison to all other 4.54, p < .001. One explanation is that, be- orientations in the 120° to 240° range. The cause Hebrew is printed from right to left, at 140-ms drop from 120° to 180° was signifi- the 120° orientation strings are read in an cant, t(\l) = 3.36, p < .005. This effect was upward direction whereas at the 240° orien- found to hold for each of the four word tation they are read in a downward direction. lengths. The respective drops (from 120° to Reading in a downward direction might be 180°) for words of lengths 2 to 5, were 136 easier than reading in an upward direction. ms, 189 ms, 113 ms, and 229 ms, respectively. A second explanation is that mental rotation A similar trend appears in the error data in a clockwise direction might be easier than (Figure 4). This upside-down effect, previously rotation in a counter-clockwise direction. reported by Koriat and Norman (1984), seems Robertson and Palmer (1983) reported a sim- consistent with other findings on the reading ilar asymmetry for compound Latin letters, of misoriented text. a finding that is inconsistent with the first Turning to the effects of string length, explanation. However, because there are major Figure 5 presents evidence for very strong differences between their study and the present interactions between string length and angular

-180°

20°- -160° NONWORDS

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STRING LENGTH Figure 5. Response time (in milliseconds) for words and nonwords as a function of string length for different angular deviations from the upright (Experiment 3). 500 ASHER KORIAT AND JOEL NORMAN

disorientation, for words, F(27, 459) = 11.68, The two intermediate deviations, 80° and p < .0001, and for nonwords, F(27, 459) = 100°, evidence intermediate effects of string 15.51, p < .0001. The results presented in length. For words, the slopes of response time this figure are very similar to those of Figure on string length are 55 ms per letter and 145 2 with respect to the four values in common, ms per letter for 80° and 100°, respectively. 0°, 60°, 120°, and 180°. The smallest angular The respective values for nonwords are 109 disorientations, 20° and 40°, evidence little ms per letter and 236 ms per letter. increase in response time with word length, the curves virtually overlapping that of the Discussion upright position (0°). Thus, word recognition appears to be indifferent to either word length The results of Experiment 3 corroborate or angular disorientation for deviations of and extend the findings of Experiments 1 and 40° or less from the upright position. 2. When the effects of both rotation and As for the error data, a two-way ANOVA string length are examined conjointly, the yielded significant effects of word length, with angular orientations included in Experiment percent errors for two- to five-letter words 3 appear to be roughly divided into three being 9.6%, 4.0%, 6.0%, and 5.7%, respec- regions. These regions are clearly evident in tively. The somewhat high error rate for two- Figures 4 and 5. First, there is a region in letter words may be due to the inclusion of which neither angular deviation nor string two very rare two-letter words. This may also length affects word recognition latency. It explain the slight increase in response times includes the upright (0°) orientation and for two-letter words (see Figure 5), as well as extends to disorientations of up to 40° or the small but significant interaction between 60°. For the second region, from about 60° length and angular deviation found for percent to 120° deviations, marked orientation effects errors. Neither of these effects was significant occur that are strongly dependent on string for nonword errors: The percent errors for length. To illustrate, orientation effects in the two- to five-letter strings were 9.5%, 5.6%, 60°-120° region (for words and nonwords 5.2%, and 7.0%, respectively. Thus, the sus- combined) increase by about 220 ms for each picion of a speed-accuracy trade-off for length additional letter. The third region includes effects seen in Experiment 1 is not corrobo- deviations in excess of 120°. These yield no rated here. further increases in response time nor an In comparison to 0°-40° deviations, the Orientation X String Length interaction. 60° deviation, although evidencing a slight In addition to the three regions mentioned increase in response time overall—the differ- above, the results for word stimuli at 60° ence between 60° and the average of the deviations represent an interesting case in three smallest deviations yielded F(\, 17) = their own right. In Experiment 3, as in 15.86, p < .001 for words and f\l, 17) = Experiments 1 and 2, they yielded significantly 22.36, p < .0002 for nonwords—shows little slower response times while at the same time increase in the effects of string length (the indicating no effects of word length. interaction between the previous comparison In sum, the results are inconsistent with and length yielded F < 1 for both words and the idea that words are processed and trans- nonwords). This is similar to what was found formed as integral units over the entire range for words in Experiments 1 and 2. If mental of disorientations. If we assume that the rotation occurs in this region, it would appear recognition of rotated words indeed involves to be holistic in nature (or piecemeal but a mental rotation process like that discussed parallel, see Funt, 1983). by Shepard and Cooper (1982), the results The results for the extreme disorientations suggest that, except for a narrow zone (around yield very similar effects of string length for 60° deviation) in which words are rotated as the four deviations between 120° and 180°. integral wholes, in all other orientations in For these deviations, the overall increase in which mental rotation occurs, it is by and response time for each extra letter is about large piecemeal. In fact, for the range of 220 ms for words and about 315 ms for angular deviations between 60° and 120° the nonwords. systematic decrease in "rate of mental rota- READING ROTATED WORDS 501

tion" with increasing string length agrees letter. If letter identity is not disrupted by rather well with a model in which single disorientation (e.g., CorbaUis & Nagourney, letters are mentally rotated in turn at a 1978; however, see Jolicoeur & Landau, 1984), constant rate. such a process should indeed result in ori- These results contrast those of Robertson entation-independent length effects. and Palmer (1983), who, using hierarchically What, then, happens in the middle region? structured patterns (large letters made up of Word recognition in this region apparently many small letters), found rotation rate to be involves neither whole-word reading nor letter- unaffected by the number of levels that had by-letter reading. Experiment 4 was designed to be rotated. In their task, however, decisions to examine what type of visual information at the local level could be carried out on the is lost or disrupted in this region. If visual basis of a single element, which, of course, is transformation does occur in this region, we not possible with the lexical decision task. may assume that it is intended to recover Our results are also not consistent with Shep- some of this information. ard and Cooper's (1982) assumption that mental rotation is holistic in tasks involving Experiment 4 the matching of a single, well-integrated familiar figure to an internal representation. If we assume that disorientations beyond Alternatively, we may conclude that in fact the upright impair letter identification, the words do not constitute "well-integrated fa- results for the intermediate region of angular miliar figures" in the sense used by Shepard deviations can be interpreted in terms of a and Cooper. letter rotation model: Words in this region It should be stressed, however, that the must be rotated letter by letter in order to be rotation function obtained (Figure 4) is no- recognized. In this model, mental rotation is tably different from that normally observed assumed to recover letter orientation. This in mental rotation studies. This raises the simple and appealing model encounters the question whether the recognition of rotated difficulty that at least as far as single-letter words involves the same sort of mental ro- identification is concerned, it is not clear that tation process observed with other stimuli. letters must be rotated to be recognized (see At the least, it would seem that additional Corballis & Nagourney, 1978; Jolicoeur & processes must be postulated to account for Landau, 1984). A further difficulty is that the results obtained over the entire range of this model fails to distinguish between the orientations, and these processes might be second and third regions, both of which specific to word recognition and reading. apparently involve some piecemeal processing. From the point of view of reading pro- An alternative model stresses the role of cesses, the region of intermediate orientations transgraphemic features in word recognition. poses a difficult problem when contrasted It has been proposed that familiar visual with the other two regions. In the first region patterns tend to be processed as a unit, with of relatively small deviations, words appear global word shape features dominating word to be recognized directly, that is, with no processing (Haber & Schindler, 1981; Lawry, need for additional processes over and above 1980). Accordingly, we may assume that those required by upright words. We may within the perceptual upright, word recogni- assume that word recognition in this region tion capitalizes on configurational, transgra- is holistic or else that it rests on the processing phemic features (Garner, 1981; Monk & of all its elements in parallel. Following Hock Hulme, 1983). These features are disrupted and Tromley (1978), we shall label this region when the word is tilted beyond the perceptual the region of the perceptual upright in word upright. If a transformation process does recognition. occur in the intermediate region, then its At the other extreme, beyond 120° devia- function might be that of recovering some of tions, there is no increased impairment with the supraletter orthographic features. increased angular deviations but a strong Experiment 4 evaluated the two models by effect of word length. This pattern suggests a contrasting two types of stimulus transfor- process in which words are read letter by mations. In the global transformation, letter 502 ASHER KORIAT AND JOEL NORMAN

strings were rotated in their entirety about The two repetitions yielded similar results their center (as in the previous experiments), and were therefore combined. whereas in the letter-upright transformation, Figure 6 presents mean response times for only the string-array direction was rotated, words and nonwords as a function of orien- but each letter remained upright. If the letter tation and format. It may be readily seen rotation model is correct, the global transfor- that the results do not conform to the letter mation should prove the easier within the rotation hypothesis. For both the 30° and perceptual upright, whereas the letter-upright 70° angular deviations the letter-upright for- transformation should prove the easier beyond mat yields longer response times than does the perceptual upright. This prediction as- the global format, and in fact this difference sumes that within the perceptual upright it is more pronounced for the 70° than for the is the orientation of the entire string that 30° deviations. Considering only the 30° and counts, whereas beyond the perceptual upright 70° angular deviations and combining words it is the orientation of the letters that matters. and nonwords, a three-way ANOVA on re- The second model stressing transgraphemic sponse times, Deviation X Direction of Ro- features, on the other hand, predicts an ad- tation (clockwise, 30° and 70° vs. counter- vantage for the global transformation even clockwise, 290° and 330°) X Format, yielded beyond the perceptual upright. significant effects for format, F(\, 17) = 105.96; p < .0001; for deviation, F(l, 17) = Method 104.52; p < .0001; and for the Format X De- viation interaction, F(l, 17) = 57.56), p< Subjects. Eighteen University of Haifa students par- .0001. The results also indicated a significant ticipated in the study for course credit. Hebrew was their primary language. effect of direction, F(l, 17) = 77.83; p< Stimuli. Two hundred and eighty eight words were .0001, which interacted with the effects of selected. Half of the words were transformed into non- deviation, F(l, 17) = 40.33; p < .0001, and words. An additional practice list consisted of 18 words with the effects of format, F(l, 17) = 29.31, and 18 nonwords. They appeared at one of five orienta- p < .0001. The effects of direction are prob- tions—0°, 30°, 70°, 290°, and 330° (labeled in a clockwise direction as in Cooper & Shepard, 1973). When the ably due to the same type of asymmetry strings were misoriented, they appeared in either one of found in Experiment 3, and this asymmetry two formats—global, with the entire string rotated as in is stronger for the letter-upright format than the previous experiments, or letter-upright, with each for the global format, and for the 70° devia- letter occupying the same location as in the global format but presented upright. tions than for the 30° deviations. It should Apparatus and procedure. The apparatus was the be recalled that since Hebrew is read from same as that used in the previous experiments. The right to left, the direction of reading is down- procedure was also the same except that the subjects ward in the 290° orientation and upward in were instructed about the stimuli and were shown ex- the 70° orientation. The triple interaction amples of the different formats and orientations. The session began with 36 practice trials, followed by two was also significant, F(l, 17) = 23.31; p < repetitions of the 288 experimental strings in different .0001. random orders. There was a short break after each block The error data indicated a similar pattern of 144 trials and a 2-min break between the two repeti- to that found for the response time data, but tions. Each block began with four filler items to allow warm-up. String orientations were preprogrammed so a similar ANOVA yielded no significant effects that for each subject and repetition 16 words and 16 apart from that due to angular deviation. nonwords appeared at the upright orientation and in each of the eight Disorientation X Format combinations. Each string appeared equally often in each of these nine Discussion arrangements across all subjects. The arrangement of each letter string varied between repetitions. The order The results of Experiment 4 indicate that of the stimuli was randomly determined for each subject stimulus transformations that disrupt whole and for each repetition. Each letter was about 1.0 X 1.0 word features while leaving letters upright cm, with a 0.1 cm gap between letters (in the global impair word recognition to a greater extent format). than do global transformations in which some of the transgraphemic features are spared. Results This appears to be true within the perceptual Response latencies in excess of 5,000 ms upright and even more so beyond it. and less than 250 ms were discarded (0.4%). These findings seem to argue against the READING ROTATED WORDS 503 idea that in the intermediate angular devia- beyond the perceptual upright some transfor- tions, words are read letter by letter, with mational process is applied to letter strings each letter first rotated to an upright orien- in an attempt to recover some of the supra- tation. If this were the case, the letter-upright letter features disrupted by string disorien- format should have yielded better perfor- tation. The nature of this process is not clear, mance (in the 70° deviation) because in this except that it appears to involve some piece- format letters need not be rotated. Rather, meal processing and that its duration depends the results are consistent with the view that on the extent of angular deviation from the even in the intermediate angular deviations, upright. word recognition tends to capitalize, to some A second account does not postulate any extent, on supraletter features. visual transformation process. It assumes that This conclusion can lead to two rather as a word departs from perceptual uprightness different interpretations of the results for the more of its transgraphemic features are lost, intermediate region. The first assumes that rendering it more difficult to recognize. Thus,

NONWORDS

Global

Letter Upright

1200 "Si

uj 1 1000

WORDS

OT 30" 70° 290° 330* 0"

ORIENTATION Figure 6. Response time (in milliseconds) for words and nonwords for letter-upright and global transformations as a function of disorientation (Experiment 4). 504 ASHER K.ORIAT AND JOEL NORMAN

orientation effects in the intermediate region present a rather nonuniform pattern with simply reflect the extent to which word rec- regard to the effects of increased disorienta- ognition takes advantage of whole-word fea- tion both on mean response time (Figures 1, tures. This account must, of course, make 3, and 4) and on the extent of string length additional assumptions to explain why ori- effects (Figures 2 and 5). Consequently it is entation effects are length dependent. difficult to propose an interpretation of the The observation that beyond the 120° de- results in terms of one unitary principle. viation there is no increased impairment of In what follows we shall examine possible performance with increased disorientation accounts for the results obtained relying on may be accommodated by both these ac- the subdivision into three regions discussed counts. Apparently, transgraphemic features above. Because in the first and third regions are lost at extreme disorientations, and word there was no effect of rotation, we shall first recognition must rely solely on letter-by-letter examine the results for these two regions, reading. relying solely on what is known about mechanisms of reading and word recognition. General Discussion The results for the first region of relatively small tilts about the upright are the most The research reported in this article com- pertinent to normal reading. It is of consid- bined a reading task with a mental rotation erable theoretical interest that word recogni- task with the aim of obtaining information tion is largely indifferent to disorientations of relevant to two different theoretical issues— up to 40° or 60° from the upright and that first, whether disoriented visual stimuli are within this range it is also indifferent to word "mentally rotated" as integral wholes or length. The indifference of lexical decision piecemeal and, second, whether words are latencies to word length has been reported read holistically or in a letter-by-letter fashion. for upright words (e.g., Frederiksen & Kroll, It was proposed that if words are processed 1976; Koriat, 1984), and the present study and transformed as integral wholes, the effects extends this finding to words tilted up to 60° of rotation should be the same for words of in either direction. The relative indifference different length, but if they are transformed to small disorientations has been reported by piecemeal, the effect should increase with Cooper and Shepard (1973) for reflection increasing word length. decisions on single letters. Furthermore, Ko- The results of Experiments 1 and 3 indi- riat and Norman (in press) found that this is cated that the effects of angular disorientation true only for normal letters, whereas reflected vary strongly with word length, and those of letters evidence a remarkably linear increase Experiment 2 suggested that these effects are in response time across the entire range of not due to the physical extent of the longer orientations. This was seen to suggest that strings but to the greater number of letters the memory representations of familiar visual they contain. On the basis of these results we patterns (e.g., normal letters) are characterized may safely reject the hypothesis that words by broad orientation tuning, allowing direct are processed and transformed as integral recognition despite small tilts. The indiffer- units over the entire range of orientations. ence of word recognition to both word length Apart from this general conclusion, how- and word orientation in the present study ever, it is difficult to offer a complete account may similarly suggest, first, that word recog- of the complex pattern of results obtained. nition in this region is based on the direct Most important, it is not clear whether the activation of whole-word visual patterns (see reading of rotated words involves the same Johnson, 1975, 1981), and, second, that the sort of mental rotation process envisioned by internal visual representation of a familiar Shepard and his colleagues or any other word is broadly tuned and can be efficiently rectification process, for that matter. The activated even when the visual stimulus de- rotation functions obtained depart consider- parts rather noticeably from its upright ori- ably from linearity. They are also quite dif- entation. Following Hock and Tromley (1978), ferent from those found for single-letter re- we label this range of orientation indifference flection decisions, especially in the region of the region of perceptual uprightness in word extreme deviations. The results, on the whole, recognition. Thus, as long as a word is per- READING ROTATED WORDS 505 ceptually upright, it appears to be recognized to involve two contrasting reading strategies, holistically. whole word and letter by letter. Because in It should be noted, though, that the indif- both response time does not increase with ference of word recognition to word length is increased disorientation, this may suggest di- also consistent with the view that word rec- rect activation of the respective codes, whole- ognition involves parallel processing of single word codes or letter codes. letters (e.g., McClelland & Rumelhart, 1981). Before examining the results for the inter- It is not clear, however, why such parallel mediate region, let us note that the contrast processing should hold only within the con- between the two reading strategies presented fines of the perceptual upright and not be- above may help resolve the paradox noted yond. by Corballis, Zbrodoff, Shetzer, and Butler The finding that words at the 60° deviation (1978): Although stimulus disorientation has evidenced length-independent orientation ef- a negligible effect on the identification of fects in all of the first three experiments single letters (e.g., Corballis & Nagourney, deserves particular attention. It suggests the 1978), it has considerable disruptive effects existence of a transitional zone on the fringe on the reading of longer strings (Kolers & of the perceptual upright where words appear Perkins, 1975). Why would an upside-down to be transformed holistically. This phenom- letter be identified as quickly as an upright enon lends further support to the idea that letter, whereas an upside-down word takes within the perceptual upright, word recogni- longer to recognize than an upright word? In tion is based on whole-word patterns. terms of the propositions offered above, this Turning next to the results for the third occurs because reading an upright word in- region (beyond 120° deviations), these seem volves the activation of a single, whole-word to suggest a rather different reading strategy code, whereas reading an upside-down word in which words are processed letter by letter involves the processing of several units in without mental rotation or transformation. sequence. If this interpretation is correct, the Single letters are identified serially and the recognition of single-letter words should be strings unitized before (or partly in unison indifferent to orientation. The results of Ex- with) lexical access. If the speed of identifying periments 1 and 3 suggest that this might single letters is indifferent to their orientation, indeed be the case: If we were to extrapolate a process of this sort should yield no effect the curves depicted in Figures 2 and 5, they of word orientation but strong effects of word would intersect at a value nearly equivalent length as was found to be the case. It would to a one-letter word. The same is true for seem that these nearly horizontal inverted nonwords as well. No single-letter words exist letter arrays induce serial scanning and result in Hebrew, but it would be instructive to see in the type of processes investigated by Kolers whether lexical decision times for single-letter and Perkins (1975). This serial processing is English words are indeed indifferent to dis- reminiscent of the reading disorder referred orientation (but see Samuel, van Santen, & to as word-form dyslexia (Warrington & Shal- Johnston, 1982). The interesting question, lice, 1980) or letter-by-letter reading (Patterson however, still remains: Why are words rec- & Kay, 1982). Indeed, the most distinctive ognized directly only within the perceptual characteristic of this syndrome is that reading upright, whereas single letters (and probably time increases monotonically with word single-letter words) are recognized directly length. This syndrome has been assumed to over the entire range of disorientations? reflect the inaccessibility of visual word forms We shall turn now to the intermediate that normally allow whole-word recognition. region involving length-dependent orientation The patient is forced to reconstruct the word effects. The interpretation of these effects from the names of the letters (Warrington & must take into account the results of Exper- Shallice, 1980). It is not clear, however, iment 4, where the global transformation was whether the letter-by-letter reading of the easier than the letter-upright transformation present study also relies on phonemic codes at 70° angular deviations. This suggests that (see Shallice, 1981). the reading of rotated words in the interme- Summing up at this point, when the first diate region can take advantage of information and third regions are compared, they appear pertaining to units that are larger than a 506 ASHER KORIAT AND JOEL NORMAN letter. Thus, although reading in this region tion. The results of Experiment 4 suggest appears to involve piecemeal processing, it that the aim of letter rotation is not simply differs from the letter-by-letter reading char- to aid in letter identification but to assist in acteristic of the third region. recovering transgraphemic features, thus al- The major difficulty in explaining the re- lowing word recognition to capitalize on larger sults for the intermediate region is that it is units, even whole words. The weaker effects not clear whether the piecemeal processing of orientation and length found for words that apparently takes place in this region than for nonwords may result from the inter- derives from mechanisms of visual transfor- play between activations at the letter and mation, from mechanisms of word recogni- word levels (see McClelland & Rumelhart, tion, or from both. One type of interpretation 1981; Rudnicky & Kolers, 1984). We should relies solely on principles of word recognition. point out that the emphasis on transgra- In terms of the contrast between the two phemic features is open to several objections reading strategies that seem to characterize (see Henderson, 1982), among them its in- the first and third regions, perhaps the sim- consistency with the finding that word supe- plest account of the results for the interme- riority is rather immune to the disruption of diate region is that they reflect either a prob- supraletter features (e.g., Adams, 1979; abilistic mixture of the strategies of whole- McClelland, 1976). word and letter-by-letter reading, or better, a An alternative account emphasizes the im- reliance on units of intermediate size. Con- portance of letter-order permutations. Several sistent with the idea of multiple units in word letter-based theories of word recognition (e.g., recognition (cf. Santa, Santa, & Smith, 1977), McClelland & Rumelhart, 1981; Paap, New- the increase in length effects with increasing some, McDonald, & Schvaneveldt, 1982) as- angular deviations may be assumed to stem sume position-specific parallel activation of from the size of the unit involved in word the appropriate codes for all the letters in a recognition: For small disorientations, the word. Perhaps disorientation beyond the per- unit is the whole word, for extreme disori- ceptual upright disrupts the letter-position entations it is the single letter, and for inter- mapping, and it is this mapping that is re- mediate disorientations it is letter clusters, stored by the rectification process. the size of which decreases with increasing In conclusion, this study of the reading of disorientation. In this interpretation, orien- rotated words has yielded a rather complex tation and length effects are seen to reflect pattern of results pertaining to the issue of the same process: Increased disorientation holism in mental rotation and word recog- reduces the size of the perceptual unit, and nition. As far as mental rotation is concerned, thus the number of effective units becomes a the results do not generally conform to the joint function of disorientation and word hypothesis that word stimuli are mentally length. If this interpretation is correct, it may rotated as integral units. This is inconsistent help explain the difference between words with Shepard and Cooper's assumption con- and nonwords. Nonwords exhibited stronger cerning the rotation of well-integrated, famil- orientation effects in Experiments 1,2, and iar stimuli. Thus, we must either reject the 3, and stronger length effects in Experiments hypothesis of holistic mental rotation alto- 1 and 3. These differences may be accom- gether, admit that words do not constitute modated by assuming that at any given ori- well-integrated wholes, or conclude that ro- entation, words require fewer units than non- tated letter strings induce different types of words of the same length. processes than those normally observed for A second type of interpretation attributes other disoriented visual stimuli. The results the length-dependent orientation effects to for words at 60° deviations do hint, however, rectification processes. The best candidate for at the possibility of holistic mental rotation, such a process is some sort of piecemeal and this deserves further research scrutiny. mental rotation in which letters are rotated As for the issue of holism in word recog- in turn at a constant rate. This model fits the nition, the results appear to indicate that data because it is conjointly sensitive to both within the perceptual upright (±60° about number of letters and degree of disorienta- the upright), word recognition relies on whole- READING ROTATED WORDS 507 word units, whereas at extreme disorientations in word recognition: A critical examination. In P. A. (120°-240°) it appears to be mediated by Kolers, M. E. Wrolstad, & H. Bouma (Eds.), Processing of visible language 2 (pp. 207-218). New York: Plenum. sequential letter identification. The interpre- Henderson, L. (1982). Orthography and word recognition tation of what occurs in the intermediate in reading. London: Academic Press. region of deviations (60°-120°) is more dif- Hochberg, J., & Gellman, L. (1977). The effect of land- ficult, though it appears that word recognition mark features on "mental rotation" times. Memory & in this region may rely on units larger than Cognition, 5, 23-26. Hock, H. S., & Tromley, C. L. (1978). Mental rotation single letters. Further research is needed to and perceptual uprightness. Perception & Psychophysics, determine whether the length-dependent ori- 24, 529-533. entation effects in this region are best inter- Huey, E. B. (1908). The psychology and pedagogy of preted in terms of mechanisms of visual reading (Reprinted 1968). Cambridge, MA: MIT Press. Johnson, N. F. (1975). On the function of letters in word rectification, mechanisms of word recognition, identifiction: Some data and a preliminary model. or both. Journal of Verbal Learning and Verbal Behavior, 14, 17-29. References Johnson, N. F. (1981). Integration processes in word recognition. In O. J. L. Tzeng &. H. Singer (Eds.), Adams, M. J. (1979). Models of word recognition. Cog- Perception of print: Reading research in experimental nitive Psychology, 11, 133-176. psychology (pp. 29-63). Hillsdale, NJ: Erlbaum. Bruder, G. A. (1978). Role of visual familiarity in the Jolicoeur, P., & Landau, M. J. (1984). 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Journal of categorize disoriented alphanumeric characters as letters Experimental Psychology: Human Perception and Per- or digits. Canadian Journal of Psychology, 32, 186- formance, 2, 80-91. 188. McClelland, J. L., & Rumelhart, D. E. (1981). An Corballis, M. C., Zbrodoff, N. J., Shetzer, L. I., & Butler, interactive activation model of context effects in letter P. B. (1978). Decisions about identity and orientation perception: Part 1. An account of basic findings. of rotated letters and digits. Memory & Cognition, 6, Psychological Review, 88, 375-407. 98-107. Monk, A. F., & Hulme, C. (1983). Errors in proofreading: Frederiksen, J. R., & Kroll, J. F. (1976). Spelling and Evidence for the use of word shape in word recognition. sound: Approaches to the internal lexicon. Journal of Memory & Cognition, 11, 16-23. Experimental Psychology: Human Perception and Per- Navon, D. (1978). Perception of misoriented words and formance, 2, 361-379. letter strings. 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Psychological Documents to Be Discontinued

At its February 2-3, 1985, meeting, the Council of Representatives voted to cease publication of Psychological Documents (formerly the Journal Supplement Abstract Service) as of December 31, 1985, with the publication of the December 1985 issue of the catalog. Continued low submissions, decreasing usage, and rising costs for fulfillment of paper and microfiche copies of documents were reasons given for dis- continuing publication of the alternative format publication, which was begun in 1971 as an "experimental" publication. Authors who wished to submit documents for publication consideration in 1985 were required to do so by July 1. Authors revising documents were required to complete all revisions and submit them for final review no later than July 1. Fulfillment of orders for paper and microfiche copies of documents presently in the system and of those documents entered during 1985 will continue through December 31, 1986.