Psychonomic Bulletin & Review 2000, 7 (2), 267-283

Comparative cognition in the 19308

DONALD A. DEWSBURY University ofFlorida, GainesviUe, Florida

According to the received view ofthe history ofpsychology, behaviorism so dominated psychology priorto the 1960s that there was little research in animal cognition. A review ofthe research on animal cognition during the 1930s reveals a rich literature dealing with such topics as insight, reasoning, tool use, delay problems, oddity learning, abstraction, spatial cognition, and problem solving, among oth­ ers. Material on "higher processes" or a related topic was prominent in the textbooks of the period. Tracing academic lineages reveals such teachers as Harvey Carr, Robert M. Yerkes, and Edward C. Tol­ man as sources of this interest. The alleged hegemony of strict behavioristic psychology, interpreted as excluding research on animal cognition, requires revision. Some possible reasons for this neglect are suggested.

According to the received view of the history of the view. According to Leahey, "the central work ofmental­ study ofanimal learning and cognition, there was much istic psychology continued, but it was no longer thought interest in animal cognition among early comparative psy­ of as the study of consciousness" (p. 313). Similarly, chologists, but that interest died with the advent ofbehav­ Greenwood (1999) has recently questioned whether "the iorism, only to resurface with the "cognitive revolution" of much-touted historical 'hegemony' ofbehaviorism from the 1960s. According to a leading textbook in the field of the 1920s to the 1950s adequately reflects the rich diver­ comparative cognition, "it would not be exaggerating too sity ofresearch interests and practices during this period" greatly to say that from the 1920s until the 1960s or 1970s, (p. 18). American experimental psychology was virtually synony­ In this article, I argue that the study ofanimal cognition mous with behaviorism" (Roitblat, 1987, p. 52). Wasser­ was alive and well during the 1930s-a critical period in man (1993) writes of"a long, fallow period [in the study the development ofbehaviorism. It was during the 1930s of] the cognitive processes ofanimals" (p. 221). For Green that some ofthe pinnacles ofclassical behaviorism were (1996), "cognition simply was not a going concern in psy­ formulated; Clark L. Hull developed his mechanistic chology before the I950s" (p. 35). hypothetico-deductive theory oflearning (e.g., Hull, 1937), As a critical part ofthis hegemony ofbehaviorism, it is Edwin R. Guthrie (1935) published his Psychology of argued, studies ofcognitive processes were excluded dur­ Learning, Edward C. Tolman (1932) published his Pur­ ing this period, as behaviorists sought to explain complex posive Behavior in Animals and Men, and B. F. Skinner processes as a reflection of more simple processes of (1938) published his classic Behavior ofOrganisms. learning and conditioning. Thus, "at the beginning ofthe Thus, I believe that it is especially significant that one can 1900s psychologists' study ofcognitive processes in an­ demonstrate the pervasiveness ofresearch on animal cog­ imals narrowed into the study of associative learning... nition during this time. I shall not pretend that studies of The subfield of animal cognition arose in the 1970s" cognition were dominant; they were not. There was, how­ (Shettleworth, 1998, p. 6), and "so long as behaviorism ever, a considerable literature on animal cognition devel­ held sway-that is, during the 1920s, 1930s, and I940s­ oped during the 1930s. Obviously, it would be nice to ex­ questions about the nature ofhuman language, planning, tend the study into the 1940s and 1950s; that is beyond the problem solving, imagination, and the like could only be scope ofthe presentarticle. approached stealthily and with difficulty, ifthey were tol­ I shall focus on material published in general sources, erated at all" (Gardner, 1985, p. II). such as textbooks, two major research programs, those This view of a "cognitive revolution," in the spirit of ofNorman R. F. Maier at the University ofMichigan and Thomas Kuhn, has been challenged by Leahey (1992), who Robert M. Yerkes at the facility that would be named the pointed out that, during the years in question, behavior­ Yerkes Laboratories ofPrimate Biology (YLPB) in Orange ism was less dominant than is portrayed by the received Park, FL, and also material from many other psycholo­ gists using a variety of methods to study animal cogni­ tion during this period, loosely defined. The work ofEd­ ward C. Tolman during this period is relatively well known The author thanks Marc N. Branch, Thomas H. Leahey, and Herbert and under historical analysis elsewhere; it will be covered L. Roitblat for comments on an earlier version of this article. Corre­ spondence should be addressed to D. A. Dewsbury, Department ofPsy­ here but de-emphasized. chology, University of Florida, Gainesville, FL 32611-2250 (e-mail: Loucks (1931) quoted Bertrand Russell as noting that [email protected]). "American rats, after frantically rushing about, solve a

267 Copyright 2000 Psychonomic Society, Inc. 268 DEWSBURY particular problem by chance, whereas German rats evolve meaning, to cognitive processes that suggests hypothetical a solution out oftheir inner consciousness" (p. 511). Some constructs in the sense ofHilgard (1956). researchers of the 1930s believed there was more going on in the heads ofrats than Lord Russell realized. COMPARATIVE COGNITION IN GENERAL SOURCES DEFINITIONS Textbooks The validity ofthe hypothesis depends, ofcourse, on The 1930s were a period of extraordinary textbook the definition of cognition. Cognition often is defined publication in comparative psychology. All devoted sig­ broadly so as to include all aspects ofknowing, including nificant attention to cognitive issues. The categories used sensation, perception, learning, remembering, and deci­ in different portions of these books are summarized in sion making (Barrows, 1996; Shettleworth, 1998). Roit­ Table 1. Most devoted at least one chapter to a topic such blat (1987) defines comparative cognition as "the study as "higher mental processes" or "symbolic processes." ofthe minds oforganisms" (p. 1) and goes on to discuss The standard text in the field for nearly 30 years had mind broadly so as to include "learning, remembering, been Washburn's The Animal Mind; the fourth edition problem solving, rule and concept formation, perception, appeared in 1936. Given her background as a student of recognition, and others" (p. 2). I shall use a more narrow E. B. Titchener, it is perhaps not surprising that she conception of cognition that is focused on presumed adopted a mentalistic approach. Her key construct was the mental activity of the sort that implies the operation of "memory idea," "the ability to recall a mental image of processes other than instinctive behavior and basic con­ an absent stimulus" (p. 328). In her chapter on "Higher ditioning. I wish to focus on material often treated under Mental Processes," Washburn reviewed studies using a va­ the rubric of"higher processes," such as concept forma­ riety of tasks and showed how she believed perspectives tion, insight learning, reasoning, and ideation. Even with on the animal mind had changed from the dampening in­ this more restrictive conception ofcognition, one finds a fluence ofLloyd Morgan's canon to the psychology ofher substantial literature in the 1930s. time. What differentiates the literature to which I refer from Comparative psychology has a long history of edited the behavioristic learning literature are the categories textbooks, beginning with that ofMoss (1934). In addi­ adopted, the tasks chosen, the language used, and the un­ tion to chapters on "Discrimination," "The Neurology of derlying processes believed to be operational. The meth­ Learning," "The Conditioned Reflex," "Learning," and ods are generally behavioral, but the constructs proposed "Theories of Learning," the book included a separate to explain results are not. In this literature, research is chapter by W. T. Heron (1934) on "Complex Learning often described as concerned with insight, ideation, rea­ Processes." This chapter included such topics as insight, soning, or some such category. The tasks used generally reasoning, judgment, and abstraction. Such chapters be­ are thought to require a more complex form ofinforma­ came a staple in the successive edited texts in this field tion processing than is required in the typical learning (Heron, 1942; Riopelle, 1960; Riopelle & Hill, 1973). The literature ofthe time. Mentalistic terminology appears in same material was covered in a slightly different organi­ many, but not all, studies. Lashley (1935) believed that zational structure by Heron and Harlow in Calvin P. Stone's his cerebral lesions had not damaged a mechanism ofas­ (1951) Comparative Psychology (3rd ed.). sociation but had altered one concerned with behavior that The most successful textbook ofthe 1930s was Maier might be described as reflecting hypotheses, abstraction, and Schneirla's (1935) Principles ofAnimal Psychology. generalization, insight, and attention. Cowles and Nissen In their chapter on "Higher Mental Processes," they cov­ (1937) wrote ofthe role of"reward expectancy" (p. 345) ered studies "designed to exclude learning as the deter­ in the delayed response problem. The core theme in all mining process in the animal's behavior" (p. 444). ofthese studies is that the researchers believed that the ac­ The same general material was covered in a section on complishments observed in the animals could not be at­ "Special Tests ofIntelligence Level" within a chapter on tained through basic learning processes but required the "Testing Reactive Capacities" in Volume I ofthe compre­ postulation ofsome higher (cognitive) processes. hensive three-volume Comparative Psychology of War­ For Greenwood (1999), what differentiates the early den, Jenkins, and Warner (1935). The context in this work literature from that after the cognitive revolution is that is slightly different, as the studies are presented as tests of cognitive processes were regarded as intervening variables higher forms ofintelligence rather than ofseparate cogni­ during the earlier period but as hypothetical constructs tive abilities. later. However, this distinction is complex, and different The last ofthe 1930s textbooks was Norman L. Munn's interpretations are extant. The distinction was rarely made (1933) An Introduction to AnimalPsychology. This book in the field ofanimal cognition ofthe 1930s, the period is something ofan outlier, as suggested by its subtitle, The at hand. It is clear that at least some ofthe students ofan­ Behavior ofthe Rat. Although dealing almost exclu­ imal cognition at the time attributed a reality, or surplus sively with rats, not generally thought ofas the epitome COMPARATIVE COGNITION IN THE 1930s 269

Table 1 isons to a section on "Cognitive Aspects of Behavior." Categories of Higher Process Studies Here, Nissen discussed such issues as the genesis ofper­ Used in Textbooks ofthe 1930s ception, pattern specificity, the selective process of at­ Heron (1934, 1942) tention, concept formation, and symbolization and lan­ Complex Learning Processes Insight guage. Many ofthe studies discussed are from the time Reasoning period emphasized in the present discussion. Nissen con­ Use oftools cluded that "it is in the cognitive rather than the motiva­ Delayed reaction tional aspects ofbehavior that we find the significant axes Multiple delayed reaction (1942) ofbehavioral evolution" (p. 380). Methods ofbridging the interval Double-alternation problem Multiple-choice problem Review Articles Judgment Similar emphases can be seen in review articles ofthe Abstractions and generalizations time. In an article on "Cerebral Control Versus Reflex­ Token rewards (1942) ology," Lashley (1931) responded to an earlier criticism Maier & Schneirla (1935) by Hunter (1930a) and defended the notion that the be­ H~herMenwIProc~ses Delayed reaction havior ofrats in a variety ofsituations required explana­ Sudden drop in learning curve tion in terms ofcentral processes, as opposed to the pe­ Abstraction ripheral reflexology suggested by Hunter. Tolman's (1932) Multiple choice Purposive Behavior in Animals and Men is full of sug­ Reasoning gestions regarding cognitive processes. He suggested that Other animal forms (Kohler and others) "behavior as behavior, that is, as molar, is purposive and is Washburn (1936) H~herMenwIProc~ses cognitive" (p. 12). Luh (1937) published an article entitled Delayed responses "A Comparative Approach Toward the Psychology ofCog­ Abstraction nition," in which he argued for a cognitive approach. The temporal maze "Insight" THE RESEARCHERS "Hypotheses" Reasoning Use oftools and mechanical devices Summarized in Figure I are the academic lineages of Recognition of Landmarks many of the psychologists who did work in animal cog­ Munn (1933) nition during the 1930s. Although there were many such Symholic Processes psychologists, there are especially strong links to Ed­ Delayed reaction ward C. Tolman ofthe University of California, Berke­ Multiple-choice problem ley, Robert M. Yerkes, of Yale and the YLPB, and Har­ Double alternation in temporal maze vey Carr, of the University of Chicago. Tolman, a Warden et a!. (1935) Harvard PhD of 1915, established a major animallabo­ Special Tests ofIntelligence Level Problem method ratory and trained some outstanding students at Berkeley. Multiple-plate task Otto L. Tinkplepaugh and John T. Cowles went from Imitation task there to the YLPB. Yerkes, a Harvard PhD of 1902, not Delayed-response method only produced an impressive group ofhis own doctoral Hamilton quadruple-choice method Yerkes multiple-choice method students but also attracted those ofothers to work as staff Box-stacking task members at the YLPB after completing doctorates else­ where. Carrreceived a University ofChicago PhD in 1905, having worked with John B. Watson, James Rowland An­ geli, and John Dewey, among others. He became a tire­ of cognition, Munn nevertheless discussed many of the less advocate ofthe functionalist school ofpsychology. standard topics in animal cognition ofthe time, including Ofthese three key figures, only Carr produced students delayed reactions, the multiple-choice problem, and dou­ who were especially effective in generating a third gener­ ble alternation. ation for the 1930s field ofanimal cognition. Carl 1. War­ It is apparent that, through all ofthe textbooks ofthe den, a largely overlooked psychologist at Columbia Uni­ period, a section on what we would now regard as com­ versity, produced the most, but W T. Heron, at the University parative cognition was treated as an essential part. The of Minnesota, and Walter S. Hunter, during his period at organizational structure varies a bit from volume to vol­ Clark University, also were effective in this regard. ume, but, in general, the same material was covered in each Several others were important. Although Karl S. Lash­ work. ley's 1914 PhD at Johns Hopkins was in Zoology, he func­ In the classic review ofcomparative studies in the major tioned as a psychologist for most of his life. Lashley ar­ handbook of experimental psychology, S. S. Stevens' gued against a psychology based on chain reflexes and in Handbook ofExperimental Psychology, Nissen (1951) favor ofcentral regulation, finding himselfbetween "the devoted over 40% ofa chapter on phylogenetic compar- Scylla ofreflexological dogma and the Charybdis ofmen- 270 DEWSBURY 3"·

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talistic implication" (Lashley, 1938, p. 125). From Lash­ in animals with the requisite neural apparatus. He believed ley, we can see a fourth generation through Calvin P. Stone such performance characteristic ofonly apes and men. to Harry F. Harlow to Abraham H. Maslow, later a famous Language and symbolism. At a still more abstract humanistic psychologist, and Walter F. Grether. and cognitive level, Yerkes and his colleagues sought ev­ Lurking in the background ofthis network was the in­ idence ofthe use ofsigns and symbols as precursors of fluence ofJohn B. Watson. He exerted a strong influence linguistic capacity. They found evidence ofwhat Yerkes on both Carr and Lashley during their graduate training regarded as real, but rather minimal, use of symbols in and was a good friend and frequent correspondent of chimpanzees. Sign learning, for Yerkes, entailed the de­ Yerkes. It may seem strange that Watson, regarded as the velopment of new meanings for stimuli as they become founder of behaviorism, was perhaps the focal grandfa­ associated with particular events through repetition and ther of 1930s research in animal cognition, but this is less could be a matter of simple conditioning. Symbols in­ surprising when one considers his functionalist back­ volved representation. Operationally, the imposition of ground at the University ofChicago, where he received his delays provided a primary method with which the exper­ PhD in 1903, and his early lines ofresearch, rather than imenters tested for symbolic representation. Yerkes and his hard-line behaviorism ofthe 1920s. his associates sought evidence ofsymbolic processes in studies ofdelayed response, discrimination learning, and TWO MAJOR PROGRAMS delayed reward. Much ofthis research is reviewed below.

I now discuss the substantial programs of Yerkes and Norman R. F. Maier Maier, which illustrate the underlying theme that these Norman R. F. Maier ran a very different, and less com­ psychologists believed nonhuman animals to be capable prehensive, research program. Maier's work reflects his ofcognitive performance that could not be explained by background; he spent part ofhis graduate career with the the associationistic hypotheses ofthe behaviorists ofthe Gestalt psychologists at the University of Berlin before day. While relying on behavioral observations and thus, completing his PhD with John F. Shepard at the Univer­ in some sense, behaviorists, they believed that some more sity ofMichigan. He then spent 2 years at the University complex phenomena could not be explained by condi­ ofChicago working with Lashley. tioning theory. In this they had a fundamental disagree­ During the 1930s, Maier conducted an extensive se­ ment with such theorists as Edward L. Thorndike and ries ofexperiments on a process he termed "reasoning." Kenneth W. Spence. He regarded behavior resulting from contiguous experi­ ences as reflecting a learning process, or"process L," and Robert M. Yerkes, that from isolated experiences as reflecting reasoning, or His Students, and His Associates "process R." It was the ability to combine two noncon­ Robert M. Yerkes, who both conducted and oversaw tiguous experiences that Maier believed to reflect reason­ much research at Yale University and the Yerkes Labo­ ing, and he worked and argued hard to establish that this ratories ofPrimate Biology in Orange Park, FL, was con­ was fundamentally different from conditioning. He wrote: sistent and clear in his commitment to a language of a mentalistic cognition. In summarizing much ofthe work The term reasoning implies that something new has been done at Orange Park, Yerkes ( 1943) wrote that a new type brought about, and that in some way, past experiences have of"emergent neural process supplements trial-and-error been manipulated. It therefore seems that behaviorpatterns made up oftwo isolated experiences characterize what is procedure by making possible forms ofbehavioral adap­ meant by behavior which is the product ofreasoning (Maier, tation which strikingly resemble those which in us are 1931 b, p. 336). known to depend upon perception of relation, ideation, insight, or understanding" (pp. 169-170). Maier relied mainly on "table problems" with rats. In Ideation. Although Yerkes stopped short of propos­ one variation (Maier, 1929b), in a room with which the ing that these abilities matched our own, he proposed rats were already familiar, they were trained to climb that performance in completing complex tasks reveals in three ringstand ladders in order to arrive at an elevated chimpanzees "ideational processes." These ideational pathway that connected several items in the room. A table, processes provided the basis for the research program in one corner ofwhich was screened offfrom the larger part cognition at the Yerkes laboratories. He selected, among ofthe surface, was in the room. The rats learned to go from others, four primary areas of research as typifying the the table to other parts ofthe room. For their second ex­ appearance ofideation and thus these processes: the string perience, the rats were guided to climb from the base of test, the box test, the selective transportation test, and the a ringstand to the pathway and thence to food, which had multiple-choice test. been placed on the corner of the table. The animal was Yerkes (1934) believed that these forms of behavior tested by placing it on the table across from the screen to "obviously presage those expressions ofhuman curiosity see if it would combine its two experiences and climb and originality we call invention and discovery" (p. 107). down from the table and back up to reach the elevated This ideational behavior differed from basic learning, as pathway and the food. Because they had to combine two revealed by sudden solutions, and would be possible only separate experiences, Maier (l929b) concluded that the 272 DEWSBURY

rats solve the problems "without 'trial and error,' but with Yerkes's favorite indicators of ideation. Working with intelligence and insight" (p. 88) and that "patterns or Yerkes, Bingham found that chimpanzees were quite effi­ Gestalten" (p. 92) were involved. cient at solving these problems. As evidence ofideation, The task resembles the Umweg, or detour problem. By Bingham (1929a, p. 56) listed "(a) abrupt changes; (b) re­ varying the conditions somewhat, it could be made into flective pauses; (c) anticipatory looks; (d) confluent acts; one in which the rats had to learn to choose the shortest (e) transfers of skill and plan; (f) overnight solutions; ofseveral paths to a goal (Maier, 1929b). Maier (1929b) [and] (g) transformation as revealed in corrective adjust­ ran many variations on this fundamental experiment. In ments." Yerkes (1943) added an observation from work of another variation (Maier, 1929a), it became a test ofthe Yerkes and Spragg (1937), emphasizing the suddenness delayed response. with which solutions can be reached. Brainard (1930) In the three-table problem ofMaier (1932d), three tables compared the performance ofchildren to that ofapes and in a room were connected by an elevated pathway. The observed solutions consistent with Kohler's. rats were permitted to explore the apparatus and then to Stick problems. Kohler (1925) observed sudden so­ feed on one ofthe three tables. They were then placed on lutions to a variety of stick problems in which animals one ofthe other tables to see whether they would use the had to use, and sometimes alter, sticks to rake in various pathway to get to the table that contained food. When he incentives. Yerkes (1927a, 1927b) observed similar be­ found that rats could do this, Maier concluded that the rats havior in a gorilla. Pechstein and Brown (1939) studied could reason. the problem and concluded that solutions resulted from Simultaneous with this rat research, Maier conducted a trial and error and from chance, rather than insight. By program ofresearch on reasoning in humans (e.g., Maier, contrast, working at Yale, Jackson (1942) utilized stick 1930b, 1931a, 1933, 1936) and published several review tests similar to those used by Kohler (1925). Jackson con­ and theoretical papers (Maier, 1931 b, 1937, 1940). trasted the performance ofyounger animals, who seemed to act via trial and error, with that ofolder, experienced THE LITERATURE ON animals whose solutions "tended to be ofthe 'insightful' ANIMAL COGNITION IN THE 1930s (sudden) type" (p. 234). These experiments can also be in­ terpreted in the context oftool use (see below). In this section, I summarize a broad range of studies The box-and-pole test. Yerkes and Spragg (1937) of animal cognition from a variety of laboratories, in­ used a box-and-pole test, in which a banana was placed cluding those ofYerkes and Maier. In the interest ofspace out of reach in a long, narrow box with open ends that conservation, I emphasize the methods used and the con­ was anchored to the ground. The only way for the animal clusions reached, since these are most critical to the pre­ to get the banana was to use a long pole to push it out the sent argument. The procedures used by a wide variety of opposite end. Yerkes and Spragg particularly noted the authors studying animal cognition are summarized in performance of one chimpanzee, Mamo, who, they felt, Table 2. Some ofthese classifications are somewhat ar­ showed every evidence ofhaving solved the problem sud­ bitrary, since different authors might use the same task to denly as ifwith insight. infer different cognitive processes and a single author Simple inference. Grether and Maslow (1937) stud­ might postulate more than one process. ied several species ofmonkeys in a situation that required that, when shown that one oftwo food cups was empty, Insight they must select the other one. Grether and Maslow con­ With the appearance in English ofKohler's (1925) The cluded that "mechanical principles, such as 'trial-and­ Mentality ofApes, interest in the topic ofinsight was gal­ error' and 'conditioning,' do not appear adequate to ex­ vanized. The issue concerned whether performance plain the 3 manners ofattaining success on the problem" could be explained with principles ofThorndike's trial­ (p. 133) and favored Maier's "reasoning" interpretations. and-error learning or required a process such as insight. Chain-and-stake problems. In an article on "insight Umweg problems. In the simplest task, the animal had and foresight in various animals," McDougall and Mc­ to solve the detour (or Umweg) problem, which, in various Dougall (1931) used chain-and-stake problems in which guises, required that it move away from a goal in order an animal was chained to a tree and the chain was looped to get around a barrier keeping it from the goal. As noted, around a stake. When the animal moved as close to an in­ some ofthe problems ofMaier (1929b) can be viewed as centive as possible under these circumstances, the in­ Umweg problems. Hamilton and Ballachey (1934) re­ centive remained just out ofreach. To solve the problem, ported fortuitous observations ofa rat solving an Umweg the animal had to retreat and separate the chain from the problem. stake so that it allowed full extension and access to the Box stacking. The famous box test, in which the ani­ incentive. There is an obvious affinity to the Umweg tasks mal had to correctly place one or more boxes underneath described above. The subjects solved the problem. The a lure that had been suspended from the ceiling in order authors believed that the solutions reflected not only in­ that it may reach the lure (Kohler, 1925), was one of sight but foresight as well, and they criticized the Gestalt COMPARATIVE COGNITION IN THE 1930s 273

Table 2 A Provisional Classification of 1930s Studies in Animal Cognition General Articles and Reviews Double Alternation Lashley (1931); Tolman (1932); Luh (1937) Hunter (1929, 1930b); Hunter & Nagge (1931); Gellerman (l93Ia, 1931b, 193Ic); Karn (1938); Karn & Malamud (1939); Insight Karn & Patlon (1939) Umweg Problems Hamilton & Ballachey (1934) Multiple Choice Box Stacking Yerkes (1934); Spence (1939) Bingham (1929a); Brainard (1930) String Problems Stick Problems Adams (1929); Harlow & Setllage (1934); KlUver (1933); True­ Pechstein & Brown (1939); Jackson (1942) blood & Smith (1934); Finch (1941) Simple Inference Grether & Maslow (1937) Abstraction Chain-and-Stake Problems Revesz (1925); Lashley (1938) McDougall & McDougall ( 1931) Atten/ion Puzzle Boxes Maier (1930a); Lashley (1938) Adams (1929); McDougall & McDougall (1931); Transposition Lashley (1935); Pechstein & Brown (1939) Perkins & Wheeler (1930); Schiller (1933) Concept Formation Reasoning Fields (1932,1935, 1936a, 1936b) Maier Room-and-Table Problems Spatial Cognition Maier (I 929a, 1929b, 1930b, 1931 a, 1931 b, 1932a, 1932b, 1932c, 1932d, 1933, 1934, 1935, 1936, 1937, 1938a, 1938b, Forward-Going Tendency Dashiell (1930) 1940); Wolfe & Spragg (1934); Campbell (1935); Maier & Cognitive Maps Curtis (1937); Maier & Sabom (1937); Maier & Sherburne (1938); Loevinger (1938) Hsaio (1929); Tolman & Honzik (1930); Gilhousen (1931); Enclosed-Maze Problem Keller & Hill (1936); Kuo (1937) Shepard (1933) Symbolism Token rewards Tool Use Wolfe (1936); Cowles (1937) Fritz (1930); Kluver (1933); Yerkes & Spragg (1937) Assorted Tasks Delay Problems Yerkes & Nissen (1939); Nissen (1938); The Delayed-Response Task Nissen & Taylor (1939); Finch (1942) Tinklepaugh (1928, 1932); Harlow (1932); Harlow, Uehling, Problem Solving & Maslow (1932); Maslow & Harlow (1932); McAllister (1932); Jenkins Triple-Plate Problem Box Yudin & Harlow (1933); Foley & Warden (1934); Keller (1934); Jenkins (1927); Shuey (1931, 1932); Fjeld (1934); Wilson (1934a, 1934b); Nissen, Carpenter, & Cowles (1936); Riess (1934) Cowles & Nissen (1937); Nissen, Riesen, & Nowlis (1938); Cooperative Problem Solving Harlow & Bramer (1939); McCord (1939a, 1939b); Yerkes & Crawford (1937, 1941) Nissen (1939); Cowles (1940); Nissen & Harrison (1941); Finch Selective Transportation Test (1942) Bingham (1929b) Delayed Alternation Reversal Learning Loucks (1931); Elder & Nissen (1933); Nissen & Taylor (1939) Nissen, Riesen, & Nowlis (1938) Delayed Matching /0 Sample Finch (1942) Hypotheses Delayed Reward Krechevsky (1932, 1933a, 1933b, 1935) Riesen ( 1940) Imitation Warden & Jackson (1935) Oddity Learning McCulloch & Nissen (1937); Nissen & McCulloch (I 937a, Language 1937b) Yerkes and Learned (1925)

psychologists for not incorporating foresight into their (p. 254). Lashley (1935) found cerebral lesions to have interpretations. little effect on learning but to interfere with performance Puzzle boxes. With the puzzle boxes pioneered by in latch-box problems "and that retardation from cere­ Thorndike (1898, 1911), an animal was confined in a brallesions is due rather to disturbance ofsuch function box and had to operate a manipulandum ofsome kind in as are implied by the terms attention, insight and initia­ order to escape. Although Thorndike believed that the tive" (p. 38). Pechstein and Brown (1939), by contrast, problem was solved through trial and error, other inter­ concluded that the performance of their primates in pretations were offered during the period under consid­ puzzle-box situations did not require the postulation of eration. Adams (1929) used a similar approach and be­ insight. lieved that he found evidence ofinsight as a special form ofadaptation, and he sharply criticized behaviorists for Reasoning trying to extend principles of conditioning to complex Research aimed at demonstrating a reasoning process processes. McDougall and McDougall (1931) believed was done primarily by N. R. F. Maier as was discussed that actions in their puzzle boxes "clearly imply insight" above. Maier (1932a) found that young rats were inferior 274 DEWSBURY

to older ones in combining separate experiences. Maier Delay Problems (1932c) studied the effects of cortical lesions on tasks Easily the most popular tasks in studies of animal that he believed requiredjust the learning process versus cognition during this period were problems with built-in those that required reasoning. Whereas the lesions did not delays. The basic notion was that because an appreciable affect performance in the learning task, they caused decre­ interval intervened between the presentation ofthe task ments in the reasoning task in a manner consistent with and the opportunity for a response, some kind ofrepre­ Lashley's notions ofmass action (i.e., the larger the lesion, sentation had to be utilized. the greater the deficit). Maier refined the lesion work in The delayed-response task. In the most basic, and later studies (Maier, 1932b, 1934; Maier & Sabom, 1937). most popular, delay task, the delayed-response task in­ In later work, Maier (1938a, 1938b; Maier & Sherburne, troduced by Hunter (1913), the animal is shown which of 1938) required rats to integrate four separate experiences. several alternatives is correct and an interval is imposed Maier and Curtis (1937) studied within-day trends in before a response is possible. There were many variations problem-solving performance. on the delayed response theme during the period under As might be expected, Maier's research proved con­ consideration. McAllister (1932) placed the problem in troversial. Whereas Campbell (1935) supported Maier's the context ofthe natural history of animals in the field distinction between learning and reasoning, Wolfe and responding to stimuli not present at the time. Some ofthe Spragg (1934) repeated the experiments and concluded studies were comparative in nature, the critical question that "solutions were achieved in a manner entirely consis­ being how long a delay could be tolerated by different tent with ordinary learning principles" (p. 469). Wolfe and species (e.g., Harlow, 1932; Harlow & Bromer, 1939; Spragg used four different test situations, three ofwhich Harlow, Uehling, & Maslow, 1932; Maslow & Harlow, were adaptations ofapparatus used by Maier (1929a) and 1932; McAllister, 1932; Yudin & Harlow, 1933). Keller one a reproduction ofMaier's (1932b, 1932c) three-table (1934) presented a critique ofan earlier study by R. M. problem, in their critical reevaluation of Maier's work. Yerkes and D. N. Yerkes (1928) suggesting that chim­ Maier (1935) defended his distinction. Loevinger (1938) panzees showed delayed responses with color as an iso­ concluded that Maier's results reflected neither reasoning lated cue. nor learning ability. The point to be emphasized is that There was much interest in how the animals performed throughout this whole, extensive program, the focal issue the tasks, particularly with respect to whether some bod­ was that of whether the results could be explained with ily orientation was necessary to mediate the delay (e.g., traditional learning principles or necessitated the postu­ McAllister, 1932; McCord, 1939b; Nissen, Carpenter, & lation ofsome higher, more cognitive, process. Cowles, 1936; Tinklepaugh, 1928; Wilson, 1934a, 1934b). Maier's mentor, John F. Shepard (1933), believed he Cowles (1940) believed that performance in this situation had demonstrated reasoning on the basis ofexperiments was continuous with, and not qualitatively different from, in an enclosed maze. From a central field, four alleys, that in other discrimination learning situations. McCord 11-17 ft in length, led to four boxes. Rats were allowed (1939a, 1939b) inferred only that the process involved in to explore the maze, and food was then presented in mediating the delay must be central rather than periph­ one ofthe four boxes. Because they then went to the ap­ eral. Nissen, Riesen, and Nowlis (1938) studied delayed propriate box, Shepard inferred that they displayed rea­ response learning in an apparatus in chimpanzees and soning, "combination, in advance ofthe reaction, offac­ concluded that a "symbolic mechanism" (p. 384) was tors from separate experiences, and where such separate operative but that it is highly developed for spatial cues experiences involve essential contradictory or differing el­ and not for visual stimuli. Nissen and Harrison (1941) con­ ements which must be functionally recognized" (p. 149). firmed the importance of positional cues. Tinklepaugh (1932) found that chimpanzees did better than monkeys Tool Use in a multiple-delayed-response task, in which the correct There is overlap between studies oftool use, including alternative in several pairs had to be retained simultane­ the box-and-stick problems and the box-and-pole prob­ ously; several boys did more poorly than the apes (Tin­ lems of Yerkes and Spragg (1937), discussed above. In klepaugh, 1932). By substituting a less preferred incen­ addition, Fritz (1930) observed a rat that used a wood tive for a more preferred one, Tinklepaugh (1928) elicited shaving as a tool by dipping it into water repeatedly, lick­ reactions that led him to believe that his "monkeys demon­ ing the water from it each time. strated ... representations standing for certain quantita­ Whereas R. M. Yerkes and A. W Yerkes (1929) had pro­ tive aspects ofthe reward" (p. 236), as well as which al­ posed that there is a great gulfbetween the monkeys and ternative was correct. apes regarding use ofinstrumentation, Kluver (1933) con­ Delayed alternation. Less popular was the delayed­ duced a series of207 experiments involving sticks, ropes, alternation task of Carr (1917, 1919), in which animals sacks, rings, and brushes with a cebus monkey and con­ had to alternate successive responses with a delay im­ cluded that tool use was considerable and closer to that posed in between. The notion was that the cue is less ob­ ofthe apes than suggested by Yerkes. vious as it comes from the animal's own response. Loucks COMPARATIVE COGNITION IN THE 1930s 275

(1931) studied the effects of cortical lesions, Elder and Studies were done in a large, outdoor apparatus in which Nissen (1933) studied delayed alternation in raccoons, the animal moved through an entrance alley to a chamber and Nissen and Taylor (1939) studied chimpanzees. onto which opened nine doors, each leading to a large Delayed matching to sample. Finch (1942) extended box. On any given trial, some doors were open and some the work on delayed response and added tests ofdelayed closed. The task of the animal was to pass through the matching to sample, a procedure that has become quite correct door and box to obtain food. Within a problem, popular in studies of animal cognition in recent years. which box was correct was determined by a consistent He concluded that delayed matching to sample is easier rule, such as "the middle door," "the leftmost door," or for chimpanzees than is nonspatial delayed-response "the second from the right end." Because a different set learning. ofdoors would be open and available on each trial within Delayed reward. Riesen's (1940) study ofdelayed re­ a problem set, the actual door that had to be selected var­ ward was interpreted by both he and Yerkes as suggesting ied from trial to trial, though the same rule always applied. the operation ofsymbolic processes. Yerkes regarded the problems as "relational," because the only predictable characteristic was the spatial relation­ Oddity Learning ship among varying sets of open doors. Yerkes (1934) A program of research on oddity learning was con­ studied 4 chimpanzees, reporting that the disappearance ducted by Henry W. Nissen and T. L. McCulloch at the of errors was "abrupt"·in six cases and by gradual ap­ YLPB (McCulloch & Nissen, 1937; Nissen & McCul­ proximation in eight cases. He concluded that the solution loch, 1937a, 1937b). They showed that chimpanzees resulted from the "sudden discovery ofthe significant re­ could learn oddity problems but provided little specula­ lationship" (p. 103) because of(1) the abrupt changes in tion regarding underlying processes. error rate from 30% or more to 0%, (2) the fact that dif­ ferent boxes were open on different trials, and (3) the abil­ Double Alternation ity ofthe subjects "to respond correctly with ease and as­ In the double-alternation problem, an animal is required surance" to new settings ofopen doors. Yerkes found little to respond in a pattern, such as left-left-right-right; thus, evidence ofimitation, however. it encounters the same stimuli on successive runs and The multiple-choice research was criticized by a num­ must make a different response on the two occasions. ber of authors (e.g., Hunter, 19 I6; Spence, 1939). With Hunter (1929, 1930b; Hunter & Nagge, 1931) used the Yerkes's encouragement, Spence (1939) took up what double-alternation problem, which he had earlier intro­ was conceptually the same problem, albeit with a new duced, in an effort to analyze the stimuli controlling the "manual multiple-choice apparatus" that had earlier maze habit. He wished to discredit the hypothesis that been used by Yerkes and Bingham. The entire apparatus rats learn mazes as a chain reflex, or proprioceptively fit on a single panel that could be attached to the animal's controlled set of responses. On the other hand, he dis­ cage. Performance was much better than in the earlier agreed with Lashley's view that the underlying mecha­ work. Spence, however, remained unconvinced ofYerkes's nism was entirely central. Rather, he thought that the an­ ideational interpretation. He believed that the animals imal "can supplement proprioceptive and exteroceptive solved the problem by learning some kind ofunspecified stimuli with some symbolic process or with some central movements associated with perception. For example, if neural process" (Hunter, 1929, p. 535). The issue at hand, the animal was faced with selecting the middle of five once more, was that ofthe presence ofa central cognitive boxes, it might fixate successively on three successive process. boxes starting from the left and reach a correct solution The method was used in sets ofstudies from two other without appreciating that it was selecting the middle box. laboratories, both under the influence ofHunter. Geller­ Spence noted that animals frequently reached the solution man (1931a, 1931 b, 1931 c) studied double alternation in quite suddenly. However, he added that they often went monkeys and humans and concluded that the research from one incorrect strategy to another equally suddenly "affords additional evidence that the double alternation and sometimes switched abruptly away from a correct pat­ temporal maze may be placed with the delayed reaction tern to one that was incorrect. Yerkes (1943), however, experiment as another method ofdemonstrating the pres­ clung to his ideational interpretation ofhis own results, ence of symbolic processes in human and infra-human dismissing Spence's as being from a situation so different subjects" (Gellerman, 1931a, p. 71). Similarly, Karn and that the results could not be meaningfully compared. his associates (Karn, 1938; Karn & Malamud, 1939; Karn & Patton, 1939) published three studies ofcats and String Problems dogs in the double-alternation problem and drew a sim­ In patterned-string problems the subjects had to choose ilar conclusion regarding the importance of symbolic between two or more strings, one ofwhich was attached processes. to a piece offood. Typically, they were crossed in patterns of varying complexity. During the period under consid­ Multiple Choice eration, the problem was used in several laboratories, Clearly, Yerkes's favorite method was that of his own with several species, and with several interpretations. devising-the multiple-choice test (Yerkes, 1916, 1934). Adams (1929) studied cats with string problems and sug- 276 DEWSBURY

gested that their successful performance suggested the tion persists" (Lashley, 1938, p. 186). He believed rats ca­ use of ideas or insight. Trueblood and Smith (1934) re­ pable ofabstraction but ofa limited sort, especially ori­ peated the study with a larger sample and better controls ented toward space. and obtained less impressive results. They suggested that Revesz (1925) studied the ability of monkeys to ab­ the results could be explained by a process oftrial-and­ stract color and form from stimuli and concluded that they error learning. lack the ability for what he termed conceptual abstraction Harlow and Settlage (1934) used the problem with but did posses an ability to "cognize similarities on a sen­ monkeys. They focused on interspecies comparisons, sory plane" (p. 338) (italics in original). Thus, he believed finding that several species of monkeys seemed to per­ that "apparent abstractive performances can be reduced form in a manner superior to all nonprimates but inferior to immediate cognition of similarity" (p. 338). to that of chimpanzees and humans. They noted that Attention. One form of abstraction is selective atten­ "simple tests are solved almost immediately by all mon­ tion. Lovie (1983) analyzed the literature on attention from keys (insight)" (p. 433). More complicated problems led 1910 to 1960; relying almost exclusively on data from to more complicated interpretations. humans, he concluded that "work on attention and related In the patterned-string tests of Finch (1941) at the topics was published continuously over this 50-year pe­ YLPB, chimpanzees had to choose between two or more riod" (p. 303). strings, one of which was attached to a piece of food. In an article entitled "Attention and Inattention in Rats," Seven ofFinch's 8 chimpanzees solved all 11 problems Maier (l930a) suggested that errors in maze perfor­ given, including 2 problems that none of Harlow and mance can result from either incomplete learning or inat­ Settlage's (1934) monkeys could solve. Furthermore, tention. When he varied the task, such as by changing the whereas the monkeys showed no improvement over suc­ pathway pattern, rest period, or presence of a stimulus cessive trials, the chimpanzees did. Yerkes (1943) noted light, he found performance improved relative to that that humans typically solve such problems either by "im­ when the maze was left unchanged. He attributed the dif­ mediate perception of the essential relation and correct ference to attention and inattention. response" (p. 157) or by trial and error, with a shift to the Lashley (1938) used the Lashleyjumping stand to study former with age. He implied that the chimpanzees too are visual discriminations in rats. He presented various two­ responding in a cognitive-perceptual manner. dimensional geometrical figures as stimuli. In critical Kluver (1933) studied a large variety of problems in tests, however, he found that the rats were attending to several species of monkeys, including some patterned­ only parts of the figures and seemed to be ignoring the string experiments. He was especially interested in using remainder. Thus, the animals appeared to be attending the "pulling-in" method to alter the parameters ofitems at selectively to only a portion ofwhat the experimenter re­ the ends ofthe strings, making the task really one ofdis­ garded as the stimulus. crimination learning with the relevant stimuli attached to Transposition. In transposition problems, animals re­ the ends ofthe strings. His results are difficult to summa­ spond to relational, rather than absolute, characteristics of rize because the experiments were designed and inter­ stimuli. Some authors regarded this as evidence ofinsight. preted within the context of his Gestalt-derived system. Some ofthe experiments ofKluver (l933),just discussed, He was primarily interested in the relations between stim­ fit into the category oftransposition. uli and the extent to which these relational aspects among Perkins and Wheeler (1930) studied the phenomenon stimuli were affected by variations in the characteristics in unlikely subjects, goldfish. They found the fish capa­ ofthe stimuli. Thus, where the monkey had to make a dis­ ble ofresponding to the relational aspects ofstimuli and crimination in pulling in one oftwo weights attached to believed that the results could not be explained in terms strings, Kluver found that he could make changes in both of trial-and-error learning. Rather, they concluded that the relative and the absolute weights ofthe two boxes or "the usual criteria ofinsight arefound in the behavior of change the material or appearance ofthe boxes without the goldfish" (p. 50) (italics in original). In this, they were disrupting performance. He could thus study "equivalence following Helson (1927), who defined insight broadly as of stimuli" (i.e., which stimuli were treated as if identi­ an "ability to respond to a part in the light ofthe whole, cal). The cognitive emphasis of focusing on the per­ modification ofactivities to meet the exigencies ofa situ­ ceived relationships between stimuli that transcend their ation in a manner we may call sensible, or the transposition absolute characteristics is clear. of the general properties from one situation to another" (p. 380) and found evidence ofinsight (i.e., transposition) Abstraction in rats. The term abstraction fits in that class about which Schiller (1933) observed intermodality transposition there has been much controversy. It has been used in in minnows. Fish trained to respond to a "brighter" odor cases where the subject extracts certain information from transferred the training to prefer a brighter light. a stimulus or sets of stimuli. Lashley was a strong be­ Concept formation. It should be remembered that liever, arguing that "equivalence tests show that so long studies ofconcept formation were an interest ofClark L. as the abstract property which differentiates the positive Hull (1920). Paul E. Fields (1932) conducted a set ofex­ figure from the negative is preserved, differential reac- periments on concept formation in rats, concentrating on COMPARATIVE COGNITION IN THE 1930s 277

the ability ofthe animals to develop concepts ofgeomet­ response. Both authors were more cautious than Yerkes ric figures. He found, for example, that rats could respond in applying mentalistic terms to the behavior, although selectively to triangular shapes even when he varied such Wolfe was reluctantly willing to regard the tokens as characteristics as the area and position ofthe stimuli. He signs or symbols for the chimpanzees under limited re­ concluded that the rat "can react to qualities inherent in a strictions. particular pattern, and that it can perceive 'identity in di­ Yerkes and Nissen (1939) found evidence ofwhat they versity'" (Fields, 1932, p. 67). He went further, stating that believed to be only rudimentary symbolic processes in chim­ "the rat can react to the total organization (Gestalt) ofa pat­ panzees. Nissen et al. (1938) reported the results ofsev­ tern without previous training to that particular pattern" eral related experiments involving variations on basic dis­ (p. 67). In later studies, Fields (1935) studied the prob­ crimination learning between a white panel and a black lem in improved apparatus; Fields (1936a) found good re­ panel, one ofwhich led to food. The idea was that the sub­ tention ofthe capacity; and Fields (1936b) found concept jects would have to respond to the color ofthe stimulus, thus formation in raccoons to be superior to that in rats. eliminating positional cues, as the positions were changed between baiting and the opportunity to respond. Nissen Spatial Cognition et al. (1938) believed that a symbolic mechanism was nec­ Forward-going tendency. In his studies ofmaze learn­ essary for the subjects to solve the problem as they did. ing, Dashiell (1930) found that rats appeared to establish However, they concluded that this mechanism is highly some kind of direction orientation that acts indepen­ developed for spatial cues, but not for visual stimuli. dently ofspecific stimuli to keep them moving in the gen­ The work was followed up by Nissen and Taylor (1939) eral direction ofthe food box. He noted that the animals with tests ofdelayed alternation with nonpositional cues. could not be simply integrating a pattern ofchain reflexes The subject, Moos, succeeded in the task, thus providing and speculated that it must be "set up by some kind of further evidence ofsome symbolic capacity when dealing kinesthetic or organic posturing or set" (p. 69). with visual stimuli. Furthermore, Finch (1942) extended Cognitive maps. The study of Tolman and Honzik the work on delayed response and added tests ofdelayed (1930) has been widely cited. In one oftheir three mazes matching to sample; he concluded that delayed matching that allowed any of several routes to be taken to reach a to sample is easier for chimpanzees than is nonspatial goal, rats learned to take the shortest path. When that was delayed-response learning. blocked, they took the next shortest path. Tolman and Yerkes was still more impressed with the results of Honzik interpreted their results in relation to the princi­ Riesen (1940). Yerkes and Riesen believed that, where ple ofinsight and, indeed, entitled their article "'Insight' there was a delay of reward, especially with nonspatial in Rats." They concluded that insight was "definitely problems, symbolic processes must be at work. Subjects proved" (p. 230). In fact, their study followed an earlier given extensive training on color discrimination tasks per­ one suggested by Tolman to one of his students (Hsiao, formed very well, sometimes achieving solutions with one 1929), who also reported evidence ofinsight. However, or no errors. Riesen concluded that "this suggests that, if several studies also appeared that questioned the neces­ given the proper previous experience, animals can achieve sity ofpostulation a process ofinsight in such situations sudden solutions characteristic of problem-solving by (Gilhousen, 1931; Keller & Hill, 1936; Kuo, 1937). In­ means ofsymbols" (p. 50). Riesen further concluded that deed, Kuo (1937), a student ofTolman, stated that "such evidence of representation, or use of symbols, could be terms as 'insight,' 'reasoning,' 'intelligent,' or 'ideational found in a variety of tasks, including learning with de­ behavior,' and the like, are lazy substitutes for a more layed reward, delayed response, reasoning tests, and test careful laboratory analysis" (p. 186). ofinsight or single-trial learning. Like Yerkes, he believed that symbolic functions were commonly used with spa­ Symbolism tial stimuli but that, with other stimuli, were difficult to Among the best known studies from the YLPB during find. this period, and the most notable efforts at studying sym­ bolism, were those oftoken rewards; Yerkes (1943) treated Problem Solving these as indicative of sign learning. In the study con­ The topic ofproblem solving overlaps with several al­ ducted by Wolfe (1936), chimpanzees were permitted to ready discussed but is a convenient category for several work for poker chips, as tokens for food, by manipulat­ types ofstudies. ing a lever in a special apparatus. Either immediately or The Jenkins triple-plate problem box. The Jenkins at the end ofa session, the animal could exchange the to­ problem box was developed by Thomas N. Jenkins (1927) kens for food by using a "chimpomat" vender apparatus. in Carl J. Warden's laboratory at Columbia University. Wolfe concluded that the tokens "came to function as The chamber was round, with a food chamber in the cen­ secondary or surrogate rewards" (p. 72). Wolfe's work was ter and a start box fitted to the outside. Three metal plates extended by Cowles (1937). Tokens were found to sup­ were fitted on the floor surrounding the food chamber. port learning in such tasks as simple position habits, com­ The animal had to step on any combination ofthese three plex, five-choice position habits, visual size discrimina­ plates in order for the food chamber to be opened. Jenkins tion, visual color-pattern discrimination, and delayed believed it to be a method that could be used with good 278 DEWSBURY

control with many species. Shuey (1931, 1932) studied Hypotheses kittens in the apparatus in an effort to locate their level Working in Tolman's laboratory, Krechevsky (1932) of intelligence in relation to that ofother species. Riess came to believe that rats do not solve maze problems by (1934) found the performance of rats and guinea pigs a gradual accumulation ofhabit strength, but, rather, they to be markedly inferior to that of kittens. On the other form successive hypotheses concerning the problem, and hand, Fjeld (1934) found superior performance in rhe­ their behavior in learning problems reflects these hy­ sus monkeys. potheses. Thus, "the learning process at everypoint con­ Cooperative problem solving. In the basic paradigm sists ofa series ofintegrated, purposive behavior patterns" used by Meredith P. Crawford in studying cooperative (Krechevsky, 1932, p. 532). He explored this hypothesis problem solving, he trained individual chimpanzees to in several situations (Krechevsky, 1932, 1933a) and also solve a problem and then altered the problem so that 2 studied hereditary influences (Krechevsky, 1933b) and animals had to cooperate to achieve a solution. The ani­ brain mechanisms (Krechevsky, 1935). mals were generally effective in this endeavor. Crawford (1937) trained each to get an incentive by using a rope to Imitation pull a box to its cage. The box was then made too heavy for Since the early work ofThorndike, imitation has been one individual to pull it in. With some guidance from the regarded as suggestive ofcognitive processes, though the experiment, the animals learned to cooperate in solving the literature has produced results that are mixed at best. problem. The course of development of cooperation in During the 1930s, Warden and Jackson (1935) studied im­ two other problems was similar to that in the rope-pulling itation in rhesus monkeys using the "Warden duplicate­ task. In a related study (Crawford, 1941), chimpanzees cage method," which enabled 2 monkeys to face duplicate were trained to push four colored panels in a particular puzzle problems in adjacent cages. Warden and Jackson sequence in order to obtain a reward. For tests of coop­ found considerable imitation in about half of their tests eration, the panels were divided so that each animal had and concluded that the tendency to imitate is orthogonal access to two ofthem, and both received rewards for suc­ to problem-solving ability. cessful completion of the task of pushing the panels in the correct order. The chimpanzees learned to watch Language each other, in order to synchronize the order in which the I have found no overt studies of language during the panels were pressed, and the older ones learned to solicit 1930s. Just a few years earlier, however, Yerkes and when it was the other's tum to make a response. Learned (1925) published Chimpanzee Intelligence and The selective transportation apparatus. The selec­ Its Vocal Expression. They catalogued, using musical no­ tive transportation apparatus (Bingham, 1929b), one of tation, the various sounds made by chimpanzees. Yerkes's indicators ofideation, differed from most other tests in that the incentive was inside ofa cage, 6 ft square PERSPECTIVE and 3 ft high, and the chimpanzee was on the outside look­ ing in. The incentive, such as a banana, was suspended Having established that the study ofanimal cognition from the ceiling ofthe cage on a rod that ran on a track set was alive and well during the 1930s, it appears appropri­ in the ceiling ofthe apparatus. A knob was fixed to the ate to provide some speculations concerning the context top of the rod. The animal's task was to move the knob within which this research existed and its subsequent along the track so that the incentive would be moved to fate. one of several small doors, where it could be reached. Two related questions concern the extent to which this Progress in solving the problem went somewhat slowly. tradition was marginalized at the time and the reasons Bingham (1929b), however, was more interested in the that it has been ignored by most authors writing about manner in which the problems were solved than in their the period. rate; he concluded that ideation was involved on the basis ofa number offactors, including the versatility ofthe an­ Marginalization imals, as they could show abrupt changes, sudden initia­ Although there was much research in animal cogni­ tion, and correction oferrors. He was also impressed with tion, more behavioristic psychologists nevertheless pre­ their consistent orientation toward the goal, anticipatory vailed. The premier journal ofthe time was the Journal responses when the goal was nearly within reach, fluent ofExperimental Psychology. The only study cited here solutions, and sudden changes in the time curves, among that appeared in that journal was that ofHelson (1927). other features. Not surprisingly, Yerkes (1943, p. 162) Students of cognition did better in the Journal ofCom­ agreed with Bingham's conclusions. parative Psychology, but numerous studies appeared in Reversal learning. Nissen et al. (1938) studied rever­ such less prestigious journals as the Journal ofGenetic sal learning in chimpanzees and found that after an initial Psychology, Comparative Psychology Monographs, and decrease, the rate oflearning generally increased. This is Genetic Psychology Monographs. It would appear that the suggestive oflearning to learn. more prestigious the journal, the more it was dominated COMPARATIVE COGNITION IN THE 1930s 279

by the less cognitive approaches. The behaviorists appear the SEP, negative comments were relayed to him by his to have controlled access to the prestigious journals. friends, he had difficulties in placing his students, and he reported difficulties in getting his articles accepted in The Cognitive Approach APAjournals (Dewsbury, 1993; Popplestone, 1967). He During the period under study, experimental psychol­ eventually left the field to become a successful industrial ogists were especially concerned with defending the sci­ psychologist. He recalled that "it was this type ofcontrol entific nature oftheir discipline. Psychology, conceived over the journals that forced me to change research areas" as the study of consciousness, had reached a dead end. (Maier, 1966). The newer approaches were more positivistic, and any­ Although a member ofthe Yale faculty, Yerkes was of thing that appeared likely to shift the field back to the another generation, and his mentalistic approach was not older ways was shunned by the hard-nosed experimen­ widely respected by more reductionistic psychologists talists. Because cognition had been so closely associated during the 1930s. He had established the Orange Park with consciousness, many opposed cognitive approaches laboratories in 1930. By the mid-1930s, however, the pri­ and the mentalistic terminology often associated with it mary funding source, the Rockefeller Foundation, was in favor ofmore descriptive and positivistic approaches. having second thoughts about the direction ofthe labora­ Experimental psychologists wanted to be perceived as tory and sought the opinion of such scientists as Karl S. scientific. What could appear more "scientific" than the Lashley, Edward C. Tolman, and Heinrich KlUver. They theorems and postulates of which Hullian theory was were critical of many aspects of Yerkes's running of the composed (e.g., Hull, 1943)? All variables were defined laboratories, including what they perceived as a rather old­ in terms ofmeasurable observations rather than specula­ fashioned naturalistic approach as opposed to the more tions about the inner working ofthe mind. reductionistic approaches that were beginning to take Furthermore, the cognitivists' speculations could not hold. By the end ofthe decade, Yerkes was forced to re­ compete with the polished behavioristic theories. Hull's sign the directorship as the only way to save the labora­ was a comprehensive theory; the cognitivists could point tories. Thus, the two biggest proponents ofcognitive re­ to complex phenomena that seemed not to fit the HulIian search in the 1930s eventually left the field. paradigm, but they offered no truly integrative theory in Many histories, those generally termed "Whig" histo­ its place. Hull offered what appeared to be mathematical ries, are written by and about the winners ofcontroversies precision. (Stocking, 1965). They often tend to downplay the con­ tributions ofthe other side. It appears fair to suggest that Power and Personalities the behaviorists dominated the playing field and influ­ A number ofother factors seem relevant. During this enced the construction ofa history that ignored the sub­ period, experimental psychology was dominated by a stantial activities ofthose working on cognitive studies. group ofhard-nosed experimentalists based in prestigious Northeastern schools, especially Yale University. They Genetic Influences? dominated the prestigious Society ofExperimental Psy­ As noted above, Bertrand Russell was quoted as not­ chologists (SEP) and especially the feeder group for the ing that "American rats, after frantically rushing about, SEp, the Psychological Round Table, which drew its en­ solve a particular problem by chance, whereas German tire membership from this region (Benjamin, 1977). They rats evolve a solution out of their inner consciousness" developed a classical "good old boy" network that ex­ (Loucks, 1931, p. 511). The same contrast became a com­ cluded many outsiders. Men such as Kenneth W. Spence mon laboratory joke, according to which the rats ofTol­ and Donald Marquis went on to lead and control programs man and other cognitivi~ts were viewed as buried deep in at the major universities. They were extremely gifted sci­ thought, whereas the Hull-Spence rats only behaved. entists but also were effective in academic politics. The Some relatively obscure research suggests the possibil­ talent at Yale in the 1930s may rarely have been matched ity that there may indeed have been a genetic difference in one place and time in the history ofpsychology. They between the two populations of rats. Jones and Fennell formed a close network. Men such as Tolman, Maier, and (1965) and Fabric (1965) compared the behavior ofLong­ Yerkes, by contrast, were peripheralized to some degree Evans rats, favored in Tolman's studies, with that ofthe by geography and pedigree. Tolman was on the West black-hooded strain derived from a nonemotional strain Coast, further from the center ofpower then than it is now. developed in a study by C. S. Hall of selective breeding The cases ofMaier and Yerkes, leaders ofthe two most that became the foundation ofthe Spence colony. It should substantial programs, are instructive. Maier was a some­ be noted that these strains became established slightly what contentious Midwesterner who not only was in­ after the period emphasized here. Jones and Fennell found volved in the cognitive research but was embroiled in a gross differences in the behavior ofthe two populations controversy with some of the same Eastern scientists in a U-maze. The Long-Evans animals were deliberate concerning the genesis ofseizures in rats in conflict sit­ and highly exploratory. The "Spence animals" were more uations (Dewsbury, 1993). He was not trusted. Maier active and "seemed almost oblivious to their environ­ was told that he had been blackballed for membership in ment" (Jones & Fennell, 1965, p. 294). With some qual- 280 DEWSBURY ifications, the authors concluded that "the findings ofthis COWLES, J. T., & NISSEN, H. W. (1937). Reward-expectancy in delayed study favor the view that genetic differences were in­ responses ofchimpanzees. Journal ofComparative Psychology, 24, volved in the great debate over the nature of learning" 345-358. CRAWFORD, M. P. (1937). The cooperative solving of problems by (p. 295). Fabric studied the two strains in several situa­ young chimpanzees. Comparative Psychology Monographs, 14 (No.2), tions, including elevated runways, favored by Tolman, 1-88. and enclosed runways, favored by the Spence school. In CRAWFORD, M. P. (1941). The cooperative solving by chimpanzees of general, the Tolman rats appeared less emotional and per­ problems requiring serial responses to color cues. Journal ofSocial Psychology, 13, 259-280. formed better on elevated runways, whereas the Spence DASHIELL, J. F. (1930). Direction orientation in maze running by the rats did better in walled situations. Fabric (1965, pp. 51­ white rat. Comparative Psychology Monographs, 7 (No. 32), 1-72. 52) concluded that "the Long-Evans animals perform DEWSBURY, D. A. (1993). On publishing controversy: Norman R. F. better on elevated mazes and runways while the Hall­ Maier and the genesis of seizures. American Psychologist, 48, 869­ Spence animals performed better in closed alleys than 877. ELDER, J. H., & NISSEN, H. W. (1933). Delayed alternation in raccoons. on elevated runways." Thus, there may have been a ge­ Journal ofComparative Psychology, 16, 117-135. netic difference between the two colonies that may have FABRIC, S. I. (1965). Emotional behavior ofLong-Evans and Hall­ been selected to behave in the manner preferred in each Spence rats on walled and un walled runways. Unpublished master's laboratory. It is worth stressing that these are suggestive thesis, University ofFlorida, Gainesville. FIELDS, P. E. (1932). Studies in concept formation I. The development studies only and that more substantial and carefully re­ of the concept of triangularity by the white rat. Comparative Psy­ viewed research would be required to establish the phe­ chology Monographs, 9 (No. 42), 1-70. nomenon definitively. FIELDS, P. E. (1935). Studies in concept formation II. A new multiple stimulus jumping apparatus for visual figure discrimination. Journal CONCLUSION ofComparative Psychology, 20,183-203. FIELDS, P. E. (l936a). Studies in concept formation III. A note on the retention of visual figure discriminations. Journal ofComparative There is abundant evidence that the 1930s, far from Psychology, 21,131-136. being a period in which studies of comparative animal FIELDS, P. E. (l936b). Studies in concept formation IV. A comparison cognition were snuffed out by the onslaught of behav­ ofwhite rats and raccoons with respect to their visual discrimination ofcertain geometrical figures. Journal ofComparative psychology, iorism, was a period ofvery active and vigorous investi­ 21,341-355. gation ofcognitive processes in animals. By this I mean FINCH, G. (1941). The solution of patterned string problems by chim­ that there was much interest in, and controversy about, panzees. Journal ofComparative Psychology, 32, 83-90. the possibility that animals were capable of learned be­ FINCH, G. (1942). Delayed matching-from-sample and nonspatial de­ havior that could not be explained by processes ofbasic layed response in chimpanzees. Journal ofComparative Psychology, 34,315-319. conditioning but, rather, required the postulation ofsome FJELD, H. A. (1934). The limits of learning ability in rhesus monkeys. higher processes. I would not argue that comparative an­ Genetic Psychology Monographs (No. 5/6), 15,369-535. imal cognition in the 1930s was the same as that in the FOLEY, J. P., JR., & WARDEN, e. J. (1934). The effect ofpractice on the 1990s; I do suggest, however, that it was an important era delayed reaction in the rhesus monkey. Journal ofGenetic Psychol­ ogy, 44, 390-413. in the history ofthe field. FRITZ, M. F. (1930). 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