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DEWSBURY 67 EARLY HISTORY 68 FORERUNNERS OF COMPARATIVE PSYCHOLOGY 68 COMPARATIVE PSYCHOLOGY BEFORE WORLD WAR I 69 BETWEEN THE WORLD WARS 71 Leaders of the Reconstruction 71 New Blood for Comparative Psychology 71 The State of Comparative Psychology between the Wars 73 COMPARATIVE PSYCHOLOGY SINCE WORLD WAR II 74 Personnel 74 Funding 75 Research Centers 75 Journals 76 Academic Societies 76 Soul-Searching 76 THREE IMPORTANT POSTWAR INFLUENCES 76 European Ethology 77 Sociobiology, Behavioral Ecology, and Evolutionary Psychology 77 Comparative Cognition 78 CONCLUSION: PERSISTENT ISSUES 79 REFERENCES 81 Comparative psychology has been a part of American psy- chology since its emergence as a separate discipline. As early as 1875, William James wrote to Harvard University presi- dent Charles W. Eliot “that a real science of man is now being built up out of the theory of evolution and the facts of ar- chaeology, the nervous system and the senses” (James, 1875/1935, p. 11). G. Stanley Hall (1901), founder of the American Psychological Association (APA), regarded the study of the evolution of the human soul as “the newest and perhaps richest ﬁeld for psychology” (pp. 731–732). Future Yale University president James Rowland Angell (1905) wrote that “if the evolutionary doctrine is correct, there seems to be no reason why we should not discover the fore- runners of our human minds in a study of the consciousness of animals” (p. 458). Although the ﬁeld has changed greatly over more than a century, some of the problems addressed during this earlier era remain relevant today (Boakes, 1984; Dewsbury, 1984). There is no universally accepted deﬁnition of comparative psychology, although there is general agreement concerning which research is included, excluded, or falls near its bound- aries. Comparative psychology may be regarded as that part of the ﬁeld of animal psychology, the psychology of nonhu- man animals, not included within either physiological psy- chology or process-oriented learning studies. Such research generally is conducted on either species or behavioral pat- terns not generally utilized in those ﬁelds. Comparative psy- chology ﬁts within the broad ﬁeld of animal behavior studies, which includes research by scientists from many disciplines. Much research within comparative psychology includes no overt comparisons among species. The goals are to develop a complete understanding of general principles governing mind and behavior including its origins (evolutionary, ge- netic, and developmental), control (internal and external), and consequences (for the individual, the surrounding envi- ronment, and for subsequent evolution). Comparison is but one method of reaching such understanding. Comparative psychologists take seriously the effects of behavior on differ- ential reproduction and, ultimately, evolutionary change. In an article on the contributions of comparative psychology to child study, a favorite approach of Hall’s, Linus Kline (1904) used the term zoological psychology as a label for the ﬁeld; this may be a more accurate descriptive title than compara- tive psychology because it highlights the connection of comparative psychology with zoology—especially so-called whole-animal biology. In this chapter, I trace the history of comparative psychol- ogy from early cave paintings to the present. This entails ﬁrst a consideration of the British forerunners of comparative psy- chology and the emergence of the ﬁeld prior to World War I. 68 Comparative Psychology This was followed by a postwar period of decline, as younger comparative psychologists were unable to sustain careers, and then by a resurgence of activity between the world wars. The ﬁeld has remained active since World War II and has been strongly inﬂuenced by developments in European ethology, sociobiology, and cognitive science. EARLY HISTORY Humans have a long history of interest in animal behavior. Perhaps the ﬁrst evidence of this is from the cave paintings depicting animals in southern Europe dating from the Upper Paleolithic period, 35,000 to 10,000 years before the present. Domestication of animals began about 11,500 years ago in the Middle East and Asia (Singer, 1981). Among the ancient Greeks, Herodotus (c. 425 B . C .) described habits and behav- ior of animals and made observations on animal physiology. Interest in animals was brought to a new level by Aristotle (384–322 B . C .). He relied on observation and inductive rea- soning, not just speculation, to develop a natural history of many species. Aristotle believed in the continuity of species, though he believed species to be ﬁxed rather than evolving. He also proposed the notion of a Scala naturae, a single di- mension along which all species could be ordered. Although this idea, transformed from dealing with the characteristics of the animals’ souls to their level of intelligence, is still popu- lar today, it is widely regarded as fallacious. Evolution is branching, and species do not lie along a single continuum. During the long period from the ancient Greeks to the mid-nineteenth century, interest in animal behavior was strong in three areas. Such individuals as Frederick II of Hohenstaufen (1194–1250), John Ray (1627–1705), and Charles George Leroy (1723–1757), studied animal behavior in nature and developed the area of natural history. A second area was applied animal behavior, where domestication and selective breeding of livestock, dogs, and other species con- tinued and was perfected. Falconers developed remarkable skills in the control of behavior (Mountjoy, 1980). Finally, the relation between human and nonhuman animals became an area of interest to philosophers. The seventeenth-century French philosopher René Descartes is credited with popularizing the view that there is an absolute gulf between humans and all other species. According to Descartes, humans are the only ones to possess the immate- rial rational soul that enables abstract reasoning and self- awareness; animals are automata that can carry on simple mental functions but cannot think or have language. Darwin’s work would discredit this dichotomy. An interesting di- chotomy developed between the British and continental philosophers regarding the developmental origins of ideas. British philosophers such as John Locke and David Hume be- lieved that all knowledge originated in experience. For Locke, themind was a tabula rasa, orblankslate. Continental philoso- phers,such as ImmanuelKant, proposed theexistence of anac- tive mind with a priori properties, suchas categories, that acted on experience to produce knowledge. This geographic differ- ence can be seen in contrasting the British and continental ap- proaches to the ﬁeld of ethology in the twentieth century. FORERUNNERS OF COMPARATIVE PSYCHOLOGY The intellectual grounding for a comparative psychology was provided in the nineteenth century with the development of the theory of evolution. The notion that evolution had oc- curred did not originate with Charles Darwin but rather de- veloped with the work of such individuals as Erasmus Darwin (his grandfather), Jean-Baptiste Pierre Antoinne de Monet de Lamarck, and Robert Chambers. Darwin provided a viable mechanism, the theory of natural selection, and es- tablished that no mystical forces affected the direction of evolutionary change. Change is the result of differential re- production under prevailing circumstances. What was critical for comparative psychology was the solidiﬁcation of the idea that human and nonhuman animal behavior is continuous and thus both can be studied and compared with similar methods. This need not imply that there are no important differences between humans and nonhuman animals (henceforth called animals ), but only that there are similarities and that any dif- ferences will best be revealed through careful comparisons. Although his Origin of Species (1859) and Descent of Man (1871) are Darwin’s best-known works, The Expression of the Emotions in Man and Animals (1872) was especially im- portant for comparative psychology because it showed how a comparative study of behavior might be conducted. Among Darwin’s many contributions to comparative psychology, we should remember that in the 1871 work Darwin laid out im- portant principles of sexual selection, the manner in which individual males and females ﬁnd mates and achieve repro- ductive success. Sexual selection has been an important topic in the ﬁeld of comparative psychology in recent years. Darwin’s protégé was George John Romanes, an excellent scientist, who worked with jellyﬁsh, starﬁsh, and sea urchins (Romanes, 1885). He was also committed to demonstrating Darwin’s principle of continuity in instinct and mind in hu- mans and animals. In Animal Intelligence (1882), Romanes, like most of his contemporaries, relied heavily on anecdotes, reports of single instances of behavior provided by various Comparative Psychology before World War I 69 associates. Although he tried to be careful in selecting these, some of them are rather far-fetched and have led to a viliﬁca- tion of Romanes and his methods. His reputation was fur- ther tarnished because, in his efforts to establish continuity, he tended to anthropomorphize (i.e., attribute human proper- ties to animals). Romanes’s many contributions are often neglected. A more conservative approach to animal behavior was taken by another Englishman, C. Lloyd Morgan, in his book An Introduction to Comparative Psychology (1894). Al- though this was a multifaceted work, Morgan is best remem- bered for one sentence, which has come to be known as Lloyd Morgan’s Canon: In no case may we interpret an action as the outcome of the ex- ercise of a higher psychical faculty, if it can be interpreted as the outcome of the exercise of one which stands lower in the psy- chological scale. (p. 53) Morgan clearly believed in a hierarchy of psychological processes, with some processes being higher, or more com- plex, than others. He suggested that we can only invoke the higher processes when behavior cannot be explained in terms of lower, or simpler, psychological processes. This principle is often confused with a related dictum, the law of parsimony (Dewsbury, 1984; Newbury, 1954). The terms “law of parsi- mony” and “Occam’s razor” can be used interchangeably for most purposes. These terms refer to the assumptions made in providing an explanation rather than to the complexity of the psychological processes that are invoked. Thus, other things being equal, we should strive for explanations that do not multiply explanatory principles and that are simple explana- tions in that sense. Morgan (1894), by contrast, noted that “the simplicity of an explanation is no necessary criterion of its truth” (p. 54). It would be possible to construct an inter- pretation based on lower psychological processes but that introduces numerous additional assumptions and is thus con- sistent with Morgan’s Canon but inconsistent with the law of parsimony or one that is parsimonious but in violation of the canon. The canon implies, for example, that we should be very careful in attributing consciousness to animals. By no means did Morgan wish to suggest that animals lack con- sciousness; rather, he meant that we could invoke such a process only when necessary to explain observations that could not be explained with psychologically lower complex processes. Other investigations in the growing ﬁeld of animal behavior studies were conducted by such Britishers as Douglas A. Spalding, Sir John Lubbock, and L. T. Hobhouse and Americans such as Lewis Henry Morgan, T. Wesley Mills, George W. Peckham, and Elizabeth Peckham. Espe- cially notable was the work of Charles H. Turner on the com- parative psychology of crayﬁsh, ants, spiders, bees, and other invertebrates. Turner was an African American scientist of the time who published signiﬁcant research in major journals (see Cadwallader, 1984). COMPARATIVE PSYCHOLOGY BEFORE WORLD WAR I Building on these foundations, comparative psychology emerged as a signiﬁcant, visible discipline during the late nineteenth and early twentieth centuries in the universities of the United States (see Dewsbury, 1992). Hall had been called to the presidency of Clark University and brought with him Edmund C. Sanford, who ran the laboratory. They taught courses and attracted students to comparative psychology. The laboratory course included work on microscopic ani- mals, ants, ﬁsh, chicks, white rats, and kittens. Graduate stu- dent Linus Kline (1899), who did some of the teaching, suggested that “a careful study of the instincts, dominant traits and habits of an animal as expressed in its free life—in brief its natural history should precede as far as possible any experimental study” (p. 399). The best known of the early Clark studies were those on maze learning published by Willard S. Small (1901). Kline mentioned to Sanford that he had observed runways built by feral rats under the porch of his father’s cabin in Virginia, and Sanford suggested the use of a Hampton Court maze as an analog of the learning re- quired of rats in nature (Miles, 1930). Small and Kline con- structed the mazes and other devices in which to study the learning process in rats. Thus, the early studies were designed to mimic situations the subjects faced under natural condi- tions. The Clark program was not limited to such studies. Under the inﬂuence of Hall, there was a strong developmen- tal focus, as in Small’s (1899) study of the development of behavior in rats and in Conradi’s (1905) study of the devel- opment of song in English sparrows. James P. Porter (1906) analyzed the naturally occurring behavioral patterns of two genera of spiders. Robert M. Yerkes, under the inﬂuence of William James and Hugo Münsterberg, was a mainstay of comparative psychology during this period at Harvard. He studied the be- havior of a wide variety of invertebrates such as crayﬁsh (Yerkes & Huggins, 1903) and published one of the early classics of the ﬁeld, The Dancing Mouse (Yerkes, 1907), a comprehensive study of a mutant mouse strain. Yerkes and his students also studied a variety of behavioral patterns and species, including sensory function, such as Cole’s (1910) 70 Comparative Psychology study of the reactions of frogs to four chlorides; genetics and development, such as Yerkes and Bloomﬁeld’s (1910) study of the reactions of kittens to mice; and learning, such as Coburn and Yerkes’s (1915) study of crows. Edward Bradford Titchener dominated psychology at Cornell University. Although he is often portrayed as having opposed comparative psychology, he conducted a number of studies in the ﬁeld early in his career (Dewsbury, 1997). A prize student at Cornell was his ﬁrst PhD, Margaret Floy Washburn, who later became the second woman elected to the presidency of the APA. Her most notable contribution to comparative psychology was her book The Animal Mind (1908), that went through four editions and was the standard textbook in comparative psychology into the 1930s. Re- search at Cornell included a study of vision in ﬁsh (M. F. Washburn & Bentley, 1906) and one on learning in parame- cia (Day & Bentley, 1911). Even Edwin G. Boring (1912), future historian of psychology, published a study of phototro- pisms in ﬂatworms. The pride of the program at the University of Chicago, directed by Angell, was John Broadus Watson. Although Watson became famous later in his career for his writings on behaviorism, he did work in comparative psychology dur- ing his younger years. His dissertation, Animal Education (Watson, 1903), was an early study in developmental psy- chobiology, as Watson tried to correlate the development of learning in rats with the development of the nervous system. Watson also studied imitation in monkeys and spent several summers studying noddy and sooty terns on the Dry Tortugas Islands off Florida (e.g., Watson & Lashley, 1915). This study anticipated some later research in ethology. Many psycholo- gists who know only his writings on behaviorism are surprised by his earlier thinking on instinctive behavior (Watson, 1912). Most of the other students in animal psy- chology at Chicago worked on rats, although Clarence S. Yoakum (1909) studied learning in squirrels. Edward L. Thorndike had a brief, but extremely inﬂuen- tial, career in comparative psychology. After conducting some research with William James at Harvard, Thorndike moved to Columbia University, where he completed his PhD under James McKeen Cattell in 1898. After a year at Western Reserve University, he returned to Columbia, where he spent the remainder of his career, most of it as an educational psy- chologist. His dissertation, Animal Intelligence (Thorndike, 1898), was a classic study of cats learning to escape from puz- zle boxes; Thorndike (1911) later expanded this work with the addition of several previously published articles. He be- lieved that cats used simple trial and error to learn to operate manipulanda to escape from the compartments in which they had been enclosed; they kept emitting different behavioral patterns until one was successful. Further, he believed that virtually all learning in all species followed the same laws of trial-and-error and reward (the law of effect). This provided little impetus for comparative analysis. Thorndike’s major contribution was the development of precise methods for careful study of learning in the laboratory. In the tradition of C. L. Morgan, Thorndike generally sought to explain behav- ior in terms of relatively simple processes and eschewed no- tions of insight in creative problem solving. T. Wesley Mills took a very different approach, closer to that of Romanes than to that of Morgan. This led to a bitter exchange of mutually critical articles. Mills emphasized the importance of testing under natural conditions, writing of Thorndike’s puzzle box experiments that one might “as well enclose a living man in a cofﬁn, lower him, against his will, into the earth, and attempt to deduce normal psychology from his conduct” (Mills, 1899, p. 266). Thorndike (1899) defended his research as the only way “to give us an explanatory psychology and not fragments of natural history” (p. 415). Karl S. Lashley, best known as a physiological psycholo- gist, also had a lifelong interest in comparative psychology. He was inﬂuenced by Watson at Johns Hopkins and spent one summer working with him on the tern project. Lashley inﬂu- enced comparative psychology not only through his research and integrative writings but also through his students. Harry M. Johnson was another Hopkins-trained comparative psy- chologist, as exempliﬁed in his study of visual pattern dis- crimination in dogs, monkeys, and chicks (Johnson, 1914). Other comparative psychologists in graduate school dur- ing this period included John F. Shepard at the University of Michigan, who did many studies of learning in ants and rats (see Raphelson, 1980), and William T. Shepherd at George Washington University, who worked on a variety of species (e.g., Shepherd, 1915). Perhaps the most inﬂuential foreign-born comparative psychologist was Wolfgang Köhler, who completed a doctor- ate at the University of Berlin in 1909. Much of his career was devoted to the development and promotion of Gestalt psychology. His major work in comparative psychology was conducted on the island of Tenerife in the Canary Islands dur- ing World War I. Köhler’s best-known studies were of prob- lem solving with chimpanzees. These studies used such tasks as the stacking of boxes to reach a banana suspended above the animals’ enclosure and stick problems in which the chim- panzees had to manipulate sticks of one sort or another to reach a banana that was placed outside of the enclosure where it could be reached with a stick but not without it (Köhler, 1925). Little original theory was created during this period. The guiding theoretical framework came from the theory of Between the World Wars 71 evolution. Attention was devoted to building an empirical foundation for the ﬁeld. The range of species studied was ex- tensive. Although the study of learning came to be especially prominent, there was much research on sensory function, de- velopment, and social behavior as well. Although only a few comparative psychologists studied animal behavior in the ﬁeld, many were aware of the place of their study subjects in nature and used that awareness in understanding behavior. Although the foundations for a stable ﬁeld of comparative psychology appeared to have been laid, it was not to be—at least not yet. A number of problems arose. The major difﬁ- culty lay in the place of comparative psychology, as a study of behavior in animals, in psychology, a discipline most viewed as the study of mind and behavior in humans. Despite its intellectual and historical connections with the rest of psy- chology, comparative psychology was perceived as a periph- eral ﬁeld. Pressures were brought to bear on those trained in comparative psychology to switch and move to other re- search areas, especially applied ﬁelds. At Harvard, for exam- ple, Münsterberg (1911) wrote of Yerkes to President Abbott Lawrence Lowell that “anyone interested in those animal studies alone is in no way a real psychologist, and really no longer belongs in the philosophy department.” The situation was complicated because psychologists doing laboratory studies of animals required special facilities that were both expensive and viewed by some as undesirable because of odor and atmosphere. Some had philosophical objections to animal research. It became clear to many that the path to pro- motion was to leave comparative psychology for applied ﬁelds (Dewsbury, 1992). As a result, most comparative psy- chologists educated during these years followed such paths and left the ﬁeld. The American entry into World War I and the loss of personnel to military endeavors exacerbated the situation. BETWEEN THE WORLD WARS The period running from the late 1910s and through the 1920s was a nadir for the ﬁeld. With the old foundation for the ﬁeld gone, a new one had to be constructed. Leaders of the Reconstruction Few psychologists were in the universities to engage in re- construction. Harvey Carr and Walter Hunter, products of the Chicago program, remained active, as did Karl Lashley, who was inﬂuential in the careers of many aspiring compara- tive psychologists. After the war, Yerkes spent several years in Washington before Angell, then the president of Yale University, brought him to New Haven in 1924. Yerkes and Lashley would be pivotal in the redevelopment of compara- tive psychology that would help to establish it as a ﬁeld that has been strong ever since. Several other individuals who would lead the reformulation of comparative psychology were educated in other programs scattered about the country. Although Yerkes functioned as an administrator in Washington until 1924, he never lost sight of his plan for a re- search station where nonhuman primates might be studied (Yerkes, 1916). In 1915, he took a half-year sabbatical to conduct research on primates in California. In 1923 he pur- chased two animals, Chim and Panzee, for study, primarily at his summer home in New Hampshire. The following sum- mer, he studied primates in the colony of a private collector, Madame Rosalia Abreu in Havana, Cuba. All the while, he was publishing material on primate research (e.g., Yerkes, 1925) and lobbying various private foundations for funds for a primate facility. Finally, in 1925 the Rockefeller Founda- tion appropriated funds to support a primate facility in New Haven and, in 1929, for a feasibility study for a remote pri- mate station. Later that year, $500,000 was granted and Yerkes established the Anthropoid Station of Yale University (later renamed the Yale Laboratories of Primate Biology when it was incorporated in 1935 and the Yerkes Laborato- ries of Primate Biology upon its founder’s retirement). The facility would remain in Orange Park until 1965 and was a focal point of research on the great apes. Lashley moved to the University of Minnesota in 1917 and, with an interlude of work in Washington, D.C., remained there until he moved to Chicago, ﬁrst to the Behavior Research Fund of the Institute for Juvenile Research in 1926 and then to the University of Chicago in 1929. He moved to Harvard University in 1935, and in 1942, he became the sec- ond director of the Yerkes Laboratories of Primate Biology in Orange Park, Florida, from which he retired in 1955. New Blood for Comparative Psychology A cluster of comparative psychologists of lasting impact completed graduate training during the 1920s and 1930s. Per- haps the ﬁrst of the new generation of comparative psycholo- gists was Calvin P. Stone, who completed his PhD under Lashley at Minnesota in 1921. Stone went on to a long career at Stanford University, where he was noted for his studies of sexual behavior and the development of behavior, for his ed- itorial work, and for mentoring numerous students. Zing-Yang Kuo, a native of Swatow, Kwangton, China, completed a doctorate with Edward C. Tolman at the Univer- sity of California at Berkeley in 1923. The primary issue with which Kuo grappled during his career was the nature of 72 Comparative Psychology development and the relative roles of nature and nurture. At various stages of his career he concluded that there was either little evidence of genetic effects or that genetic and environ- mental inﬂuences were so intimately entwined that it was im- possible to separate them. Although he was able to publish some articles throughout his career, his difﬁculty in ﬁnding employment in the United States and his involvement in ad- ministrative and political turmoil in China greatly limited his inﬂuence. Carl J. Warden completed a PhD at the University of Chicago in 1922; he spent much of his career at Columbia University. Among his contributions to the ﬁeld were his writings on the history of comparative psychology, text- books, and research. The latter often entailed use of the Columbia Obstruction Box, in which a rat had to cross a shock grid in order to reach an incentive (e.g., Warden, 1931). The greater the intensity of the shock the animal was willing to endure, the greater was the animal’s drive believed to be. Henry W. Nissen completed a PhD with Warden at Columbia in 1929. He spent much of career working on pri- mate behavior under the inﬂuence of Yerkes, ﬁrst at Yale University and later at the Yerkes Laboratories of Primate Biology. He was the director of the latter facility from 1955 to 1958. Nissen is said to have known more about chim- panzees and their behavior than anyone else of his time but was a self-effacing psychologist whose inﬂuence was limited by his reticence. Nevertheless, his career was prominent enough to earn him election to the prestigious National Academy of Sciences of the United States. A remarkable cluster of students worked with Lashley at the University of Chicago during the early 1930s (Dewsbury, in press-a). Norman R. F. Maier completed a PhD with Shepard at Michigan in 1928 and, after a year on the faculty at Long Island University, went to work with Lashley during 1929–1931. He then spent most of his career back at Michigan. In comparative psychology, Maier is best known for his studies of problem solving in which he suggested that rats do not learn to solve complex processes via the simple associative processes suggested by Thorndike but rather use a process of reasoning (e.g., Maier, 1937). This was part of a fairly substantial interest in cognitive approaches to behavior during the 1930s (Dewsbury, 2000). He was also interested in the abnormal behavior, including ﬁxations and seizures, that sometimes occurred in his testing situations. Theodore C. Schneirla also completed his doctorate with Shepard at Michigan in 1928. Shepard interested Schneirla in studies of the behavior of ants, which became the focus of Schneirla’s career. In 1927, he moved to New York Uni- versity, combining his duties there with a position at the American Museum of Natural History during much of his career. He went to work with Lashley in Chicago during 1930–1931. Schneirla was a primary exemplar of the role of ﬁeld research in comparative psychology, as he made many trips to study the complex adaptive patterns of various species of ants at many sites. He also conducted notable lab- oratory research on learning in ants. Schneirla also engaged in theory construction. He advocated a concept of integrative levels, occupied by different species. With this concept, he called for caution in generalizing across widely diverse taxa. He also was a strong advocate of the epigenetic approach to development and opposed the notion that some behavioral patterns are innate. He believed that tendencies to approach toward and withdraw from stimuli of varying intensities played an important role in development (see Aronson, Tobach, Rosenblatt, & Lehrman, 1969). Frank A. Beach completed an MA degree at the Kansas State Teachers College in Emporia before going to Chicago to complete his doctorate. He worked with Lashley during 1933–1934, taught high school for a year, and then returned to Chicago for further graduate work. Lashley was gone by then, but Beach followed him to Harvard in 1936. He com- pleted the ﬁnal requirements for the Chicago PhD in 1940. Beach spent his career at the American Museum of Natural History, Yale University, and the University of California, Berkeley. He is probably best known today for a series of incisive articles he wrote about the state of comparative psy- chology and the conceptual foundations thereof. The best- known example is his “The Snark Was a Boojum” (Beach, 1950). Beach argued that throughout the ﬁrst half of the twentieth century, comparative psychologists had become interested in a more narrow range of behavioral patterns and progressively fewer species, primarily white rats. He suggested that this was not a healthy development. In “The Descent of Instinct” (1955), he criticized simplistic concep- tions of the concept of instinct. His research program was a broadly based attack directed primarily at the determinants of reproductive behavior. He was interested in the neural bases, endocrine correlates, evolution, development, and situational determinants of reproductive and social behavioral patterns. Isadore Krechevsky, later David Krech, studied ﬁrst at New York University but completed his doctorate with Edward C. Tolman at the University of California at Berke- ley. He then moved to the University of Chicago, initially with Lashley, where he remained from 1933 to 1937. A polit- ical activist, he had to change afﬁliations with some fre- quency because of difﬁculties with administrators, but he spent the last part of his career, beginning in 1947, at Berke- ley. Krechevsky (1932) showed that as rats learn mazes, they appear to form “hypotheses,” systematic runs of choices gov- erned by different rules, each of which is tried as a solution Between the World Wars 73 is sought. As with Maier’s work, this was part of the 1930s effort in comparative cognition. The ﬁfth important comparatively oriented student to work with Lashley at Chicago was Donald Olding Hebb. Hebb moved to Chicago in 1934 and accompanied his men- tor to Harvard after one year. He received a Harvard PhD in 1936. He then ﬁlled positions in Canada and, in 1942, re- joined Lashley in Orange Park. In 1947, Hebb joined the fac- ulty at McGill, from which he retired in 1974. Like Lashley, Hebb is best remembered for his contributions to physiologi- cal psychology. His The Organization of Behavior (1949) was important in the reinvigoration of physiological psychology after World War II and introduced the so-called Hebb synapse to psychology. Like Beach and Schneirla, Hebb worked to- ward reinterpretation of behavioral patterns that appeared to be innate (Hebb, 1953). His comparative interests are also ap- parent in his efforts to get studies of animal social behavior more recognition in the ﬁeld of social psychology (Hebb & Thompson, 1954). Two important comparative psychologists completed PhDs under Stone at Stanford. Harry F. Harlow completed the PhD in 1930 and spent the rest of his career at the University of Wisconsin. He spent much of his career study- ing learning in rhesus monkeys, where he developed an error factor theory, according to which the primary process during learning often involved the manner in which errors were eliminated. Harlow is best known, however, for his work on behavioral development. He found the social and reproduc- tive behavior of rhesus monkeys reared in the absence of their parents and siblings to be greatly distorted. Deﬁcits in learning were found to be much less severe. With many im- portant students educated in his program and with his editor- ial and administrative work, Harlow was a very inﬂuential comparative psychologist. The other Stanford-Stone graduate was C. Ray Carpenter, who completed his studies in 1932 with work on endocrine inﬂuences on pigeons. He is best known, however, as the “father” of primate ﬁeld research. With the help of Yerkes, Carpenter began a series of ﬁeld studies in locations such as Panama, Southeast Asia, and India (e.g., Carpenter, 1934). He established a colony of rhesus monkeys on the island of Cayo Santiago, off Puerto Rico. This was the ﬁrst sophisti- cated work on primates in their native habitats. This ﬁeld has exploded in recent years with the work of such scientists as Jane Goodall and George Schaller. Many people are sur- prised to learn of the role of a psychologist in establishing the subdiscipline of primate ﬁeld research. Carpenter spent much of his career at the Pennsylvania State University, where he also devoted much effort to documenting studies of primates and other species on ﬁlm. Other comparative psychologists completing graduate work during this era included Curt P. Richter (Johns Hopkins, 1921), Carl Murchison (Johns Hopkins, 1923), Leonard Carmichael (Harvard, 1924), Lucien H. Warner (Columbia, 1926), Otto L. Tinklepaugh (Berkeley, 1927), Winthrop N. Kellogg (Columbia, 1929), and Meredith P. Crawford (Columbia, 1935). The State of Comparative Psychology between the Wars The comparative psychologists educated during the 1920s and 1930s placed comparative psychology on a ﬁrm footing. Unlike the pre–World War I cadre, this group was successful in securing research support and in educating a next genera- tion of comparative psychologists who would carry on the tradition. Nevertheless, much was not well. This group of comparative psychologists, which appears to coalesce as a coherent unit when viewed in retrospect, did not appear so when viewed in its time. There were a number of reasons for this. Disciplines and subdisciplines become recognizable and inﬂuential with the development of a set of institutional land- marks including departments, textbooks, courses, research facilities, organizations, meetings, and journals. During this period, comparative psychology was well established in many departments, and courses were a staple in many places. In other respects, however, it lacked elements that foster cohesion. Textbooks The 1930s saw the greatest burst of publication for textbooks in the history of the ﬁeld. Margaret Floy Washburn’s The An- imal Mind had been dominant since 1908. Her fourth edition appeared in 1936. The most inﬂuential book of the era was Maier and Schneirla’s Principles of Animal Psychology (1935). The textbook provided a comprehensive overview of the ﬁeld, beginning with 11 chapters organized according to animal taxa. Material concerning receptor equipment, sensi- tivity, conduction, and the action system is provided for each group. The second part of the book is concerned with natively determined behavior, sensory function, and neural mecha- nisms in mammals. Part III addresses learning and mental processes. The most comprehensive of the works was the three- volume Comparative Psychology: A Comprehensive Treatise (1935, 1936, 1940) by Warden, T. N. Jenkins, and Warner. The ﬁrst volume deals with principles and methods; the second volume with plants and invertebrates; and the third volume with vertebrates. 74 Comparative Psychology A tradition of edited textbooks in the ﬁeld began with F. A. Moss’s (1934) Comparative Psychology . The 15 chapters included information on maturation, motivation, sensory function, learning, individual differences, animal social psy- chology, and a set of related topics. This work was followed by similar volumes from various editors at regular intervals in 1942, 1951, 1960, and 1973. An interesting approach was taken by Normal L. Munn (1933) with his An Introduction to Animal Psychology . The book is concerned solely with the behavior of laboratory rats and provides a comprehensive review of many characteristics of rats. Other Characteristics In some respects, the textbooks were the only bright spot in the institutionalization of comparative psychology during the period between the wars. One problem was that of deﬁnition, a difﬁculty that still affects the ﬁeld today. There was clearly a cadre of comparative psychologists of the sort included by my deﬁnition. The term comparative psychology, however, was used in a variety of ways. Often, it referred to all animal psychology. Important work was being done in the ﬁelds of animal learning and cognition during this period. Much of the work, however, was done within a more process-oriented framework than most work in comparative psychology as de- ﬁned here. Similarly, numerous physiological studies were conducted. The true comparative tradition was obscured, in part, because the ﬁeld lacked a clearly differentiating name, clear deﬁnition, and less permeable boundaries. A landmark was the beginning of the publication of the Journal of Comparative Psychology in 1922. The ﬁeld had had other journals, including the Journal of Comparative Neurology and Psychology (1904–1910), the Journal of Ani- mal Behavior (1911–1917), and Psychobiology (1917–1920). With the Journal of Comparative Psychology, however, the ﬁeld ﬁnally appeared to have a named journal to provide unity for the discipline. However, it was not to be. The journal be- came one of animal psychology and the primary vehicle for the publication of research in all ﬁelds of animal psychology, thus muddying the deﬁnitional problem even further. Indeed, during the 1920s, the Journal of Comparative Psychology in- cluded a signiﬁcant number of studies of human behavior (Dewsbury, 1998). A complete perspective on comparative psychology re- quires consideration of its ﬂaws as well as its accomplish- ments. Some of the writings of the time appear to be racist, at least by contemporary standards. The early volumes of the Journal of Comparative Psychology included numerous arti- cles on race differences regarding performance on intelligence tests, emotional traits, and physical development. In addition, Watson (1919) wrote that “psychologists persistently main- tain that cleanliness is instinctive, in spite of the ﬁlth of the negro, of the savage, and of the child” (p. 260), and Yerkes (1925) wrote that “certainly these three types of ape [chim- panzees, orangutans, and gorillas] do not differ more obvi- ously than do such subdivisions of mankind as the American Indian, the Caucasian, and the Negro” (p. 56). There are many aspects of the history of comparative psychology that are wor- thy of pride; a balanced view must include aspects lacking in such worth. Perhaps underlying the looseness of organization of com- parative psychology was a lack of identity among the leaders in the ﬁeld. Although all would probably have accepted the title of comparative psychologist, there was no sense of unity or effort to differentiate their work from that of other animal psychologists who often were included as “comparative psy- chologists.” There was no unifying theory of the sort devel- oped by the followers of B. F. Skinner. There was no agenda of the sort later promulgated by the European ethologists. Most comparative psychologists of the era were independent- minded individuals concerned with doing their research, re- porting it at existing meetings, and publishing it in mainline journals. There were no efforts to form new organizations or otherwise band together to deﬁne the developing tradition with any precision. As a result, the individual researchers gained respect and prestige for their efforts but they lacked real inﬂuence as a group. The subdiscipline that seems so clear in retrospect was not developed as an entity. COMPARATIVE PSYCHOLOGY SINCE WORLD WAR II The story of comparative psychology since World War II is one of developments within the ﬁeld and response to inﬂu- ences from outside. The war caused some interruption in the efforts that could be devoted to comparative psychology. The improved funding environment and the growth of universi- ties after the war, however, fueled rapid growth. Personnel Most critical was the availability of personnel. With stable positions, most of the prewar generation of comparative psy- chologists were able to develop active laboratories and pro- duce a continued output of research. As universities grew and fellowships became available, this generation, in turn, produced a new generation of comparative psychologists. In 40 years at the University of Wisconsin, Harlow alone Comparative Psychology since World War II 75 supervised 35 PhDs, including such names as Abraham Maslow, Donald R. Meyer, John M. Warren, Gerald E. McClearn, Allen M. Schrier, Leonard A. Rosenblum, and Stephen J. Suomi (Suomi & Leroy, 1982). During his career, Beach supervised 41 predoctoral and postdoctoral students (McGill, Dewsbury, & Sachs, 1978). Schneirla left a legacy of inﬂuential students including Daniel S. Lehrman, Jay S. Rosenblatt, and Ethel Tobach. Similar programs were devel- oped elsewhere. Then, of course, these students found jobs, built laboratories, and began educating yet another genera- tion. Comparative psychology still had a problem in that many who published animal research early in their careers left to become prominent in other ﬁelds of psychology. Ex- amples include Maslow, William Bevan, Jerome S. Bruner, William K. Estes, Eugene Galanter, Eleanor J. Gibson, Jerome Kagan, Quinn McNemar, M. Brewster Smith, and Dael L. Wolﬂe. Comparative psychology was always a small part of the big picture of American psychology. Nevertheless, there was a solid cadre of comparative psychologists carrying on the tradition. Funding Critical to the growth of comparative psychology was the availability of funding. Prior to World War II, most fund- ing for research came either from local sources or from private foundations, with prospective recipients making the rounds seeking research support. An exception was the Rockefeller Foundation–funded Committee for Research in Problems of Sex (Aberle & Corner, 1953). The explosive growth of support for scientiﬁc research not only increased the funding available but changed the pattern to one that in- volved the submission of research proposals that were subse- quently subject to peer review. I have analyzed funding patterns for comparative psychol- ogy for 1948–1963 at both the National Institute of Mental Health (NIMH) and the National Science Foundation (NSF) (Dewsbury, in press-b). According to my analysis, the NIMH awarded a total of 117 grants in comparative psychology for approximately $5.6 million during this period. The mean grant was for 2.5 years with an annual budget of under $20,000. The NSF program in psychobiology, not begun until 1952, awarded 72 grants in comparative psychology for a total of over $1.4 million with a mean size much smaller than those from the NIMH. The top-10 grant getters at the NIMH were Harlow, Lehrman, John Paul Scott, Richter, Eckhard Hess, Nissen, Beach, William Mason, M. E. Bitterman, and Schneirla. Half of those—Beach, Harlow, Lehrman, Nissen, and Richter—were elected to the National Academy of Sciences of the United States. Nissen, Schneirla, and Richter also were among the top-10 grant getters in comparative psy- chology at the NSF. The leading research topic in the NIMH grants was behavioral development. The NSF grants were less concentrated, with a greater emphasis on sensation and perception and general studies of behavior. This input of funding helped to create a great surge of research in compar- ative psychology, still small relative to the rest of psychology but substantial relative to that which had come before. Research Centers Although most comparative psychologists were scattered about the country in various universities, this funding en- abled the development of several centers for research. The Yerkes Laboratories of Primate Biology in Orange Park, Florida, were pivotal. Yerkes remained as director from its founding in 1930 until 1941 (Yerkes, 1943). He was suc- ceeded in turn by Lashley and Nissen. Arthur J. Riopelle and Geoffroy Bourne were the ﬁnal two directors in Orange Park. When the federal government established a program of Regional Primate Centers, Emory University, which then owned the Laboratories, moved them to their home campus in Atlanta. In addition to its directors, many other scientists such as Roger Sperry, Kenneth Spence, Austin Riesen, Paul Schiller, Hebb, Mason, and many others worked in Orange Park. From 1930 to 1965, the total budget was over $2.5 mil- lion. During the early years, the funding came almost exclu- sively from university and private foundation sources. This was reversed, and during the last ﬁve years for which data are available, over two-thirds of the funds came from the federal government. With greatly increased funding, the facility has thrived in Atlanta, albeit with a more biomedical emphasis. Harlow established and directed a primate laboratory at the University of Wisconsin. With the founding of a Regional Primate Research Center in Madison in 1964, Harlow as- sumed its directorship as well. Behavior programs also thrived in regional primate research centers in New England, Louisiana, Oregon, Washington state, and Davis, California. The behavior program at the Jackson Laboratory in Bar Harbor, Maine, was founded by John Paul Scott, who was ed- ucated as a geneticist but functioned in departments of psy- chology during much of his career. Joined by John L. Fuller, Walter C. Stanley, John A. King, and others, the program re- ceived substantial grant support and became a center for re- search on inbred strains of house mice and ﬁve breeds of dogs. It was also the site of two important conferences that helped to coalesce the ﬁeld of animal behavior studies. Another focal point developed in the New York City area. In 1937, Beach moved to the American Museum of Natural History, where he founded the Department of Animal 76 Comparative Psychology Behavior in 1942. Schneirla and Lester R. Aronson joined him in the department; Schneirla succeeded Beach as curator when Beach left for Yale University in 1946. Students such as Tobach, Rosenblatt, and Howard Topoff graduated and re- mained in the New York area. After graduating, one promi- nent student in the program, Daniel S. Lehrman, moved to the Newark, New Jersey, campus of Rutgers University, where he founded the Institute of Animal Behavior in 1959. This, too, became an important center for education and research. The focus of this whole group was on an epigenetic approach to development, and this New York epigeneticist group pro- duced numerous students and programs in the ﬁeld. Journals Beginning in 1947, the Journal of Comparative Psychology adopted a name more descriptive of its coverage: the Journal of Comparative and Physiological Psychology . That title re- mained until 1983, when it was split into three journals even more descriptive of the three prominent parts of animal psy- chology at the time: Behavioral Neuroscience, the Journal of Experimental Psychology: Animal Behavior Processes, and the reformulated Journal of Comparative Psychology . The scope of the growth of animal psychology can be seen in an analysis of the articles appearing in the Journal of Com- parative and Physiological Psychology in 1963 as compared with 1949 (Dewsbury, in press-b). The number of articles published increased by a factor of nearly 3.5 from 60 to 208. There were few footnote credits to federal funding sources in 1949; by 1963, just 14 years later, it had risen eightfold. Comparative psychologists published in other American journals as well. Some comparative psychologists found American journals uncongenial and published in the grow- ing stable of European journals, including Animal Behav- iour, Behaviour, and the Zeitschrift für Tierpsychologie (now Ethology ). Academic Societies No one academic society has emerged as the primary home for comparative psychologists. The APA remains the leading organization of psychologists, but its Division of Behavioral Neuroscience and Comparative Psychology (Division 6) is but a small part of the APA. Some psychologists have given allegiance to other psychological organizations such as the Psychonomic Society or the American Psychological Society. The Animal Behavior Society in NorthAmerican, the Associ- ation for the Study of Animal Behavior in Great Britain, and the International Ethological Congress have become the lead- ing organizations in the ﬁeld of animal behavior studies. Many comparative psychologists participate in these. The International Society for Comparative psychology, founded in 1983, has great possibilities that have not yet been realized. Soul-Searching Comparative psychologists have often assessed the state of their discipline and often criticized the directions taken. Three major articles stand out. In his famous “The Snark Was a Boojum,” mentioned earlier, Beach (1950) argued that comparative psychology had begun as the study of a wide range of topics in a wide range of species but had degenerated into the study of learning in rats. He stressed the need for a resurrection of the breadth that had earlier characterized the ﬁeld. Although Beach’s analysis was ﬂawed (Dewsbury, 1998), it was quite inﬂuential. In the second major critique, Hodos and Campbell (1969) criticized comparative psychologists’ perspective on evolu- tionary history. They argued that comparative psychologists still utilized the concept of a Scala naturae, derived from Aristotle, that implies that all species can be placed along a single great chain of being. They pointed to the branching na- ture of evolutionary history and to the need for a more realis- tic selection of species in comparative analyses. In “Reﬂections on the Fall of Comparative Psychology: Is There a Lesson for Us All?” Lockard (1971) detailed 10 myths that he thought plagued the ﬁeld. He incorporated the problems discussed by both Beach (1950) and Hodos and Campbell (1969) and added that comparative psychologists had devoted too little effort to the study of individual differ- ences, species differences, genetics and evolution, and ﬁeld research. Lockard advocated a more realistic biological ap- proach for comparative psychology. All three were effective critiques that provoked much dis- cussion and appear to have helped to stimulate change. How- ever, all three appear to have been overstatements of the problems. This may have been caused, in part, by the lack of a clear differentiation of true comparative psychology from other important, but different, parts of animal psychology. A survey published in 1980 revealed that comparative psychol- ogists remained divided with regard to both the deﬁnition and status of the ﬁeld (Demarest, 1980).