Time Capsule

How does intelligence of raccoons compare with other species? That was a topic of heated debate between 1905 and 1915 within the then-nascent field of comparative psychology.

In 1907, psychologist Lawrence W. Cole, who had established a colony of raccoons at the University of Oklahoma, and Herbert Burnham Davis, a doctoral student at Clark University, each published the results of nearly identical experiments on the processes of learning, association and memory in raccoons. They relied on E.L. Thorndike’s puzzle-box methodology, which involved placing animals in wooden crates from which the animal had to escape by opening the latch or sequence of latches. They observed the number of trials required for successful completion and the extent to which the animal retained the ability to solve the same problem more quickly when confronted again with it. Using this method, they sought what Davis called “a tolerable basis” for ranking the intelligence of raccoons on the phylogenetic scale of evolutionary development. They independently concluded that raccoons bested the abilities of cats and dogs, most closely approximating the mental attributes of monkeys.

Raccoons had attracted interest because they flourished, rather than receded, in the face of human expansion. Over the centuries, people had hunted raccoons for food and fur, decried them as agricultural pests and urban bandits, and kept them as household pets. This latter role brought the species to psychologists’ attention. Cole reported that he got the idea to work with raccoons from observing the behavior of a pet raccoon kept at a local market. At the time, most animal experiments being conducted occurred on the borderlands of academic research, nature study and domestic life. Scientists such as Charles Darwin, William James and James Mark Baldwin all developed psychological theories based upon observations of their own children and pets. Cole’s raccoons, for example, lived simultaneously as research objects and amusing pets, a relationship that shaped how these experiments were presented to and perceived by the public. Despite Davis’s protests, a widely printed newspaper story depicted his puzzle-box experiments as an example of teaching “tricks” to one’s pets.

Both popular and scientific naturalists had argued that cunning, mischief and curiosity characterized the species. Davis and Cole largely agreed with this assessment. The raccoon’s instinctual curiosity lay at the heart of Cole’s most startling claim: that the animal possessed ideas derived from complex forms of mental association, a quality that many scientists argued non-human animals did not possess. Psychologists considered curiosity a notable trait because it was a form of attention stripped of any utilitarian motive such as hunger or fear. It represented learning in its purest form. Cole claimed that his raccoons could, in certain instances, learn how to solve a puzzle box simply by being “put through” the solution by the experimenter. They did not simply rely upon the muscular associations built through trial-and-error learning, as was the case with Thorndike’s cats. Reporting on these experiments for McClure’s Magazine in 1909, E.T. Brewster suggested that raccoons counted among those animals that at least “get into the borderland that separates reasoning from other mental processes.” Review articles by leading “genetic psychologists,” such as Herbert Spencer Jennings and Robert Yerkes, suggested that that these raccoon experiments furnished some of the best evidence that “free ideas” rather than simply ingrained experiences may motivate the behavior of non-human animals.

Cole’s claims about raccoon intelligence drew ire from early advocates of behaviorism, such as Walter S. Hunter. Raccoons featured prominently in his celebrated delayed-reaction experiments, first published as his 1913 dissertation. One of the most truly comparative studies of the era, his research subjected 22 rats, two dogs, four raccoons and five human children to the same experiment. Hunter first trained the subject to associate a light source with the positive experience of being fed. Next, he detained the subject behind a gate, but permitted it to observe three light bulbs, one of which was briefly illuminated and then turned off. The task was to remember the position of the lighted bulb and to approach it and collect the food reward. Hunter defined success in terms of the subject’s repeated correct approach to the stimulus. He manipulated the duration of the delay before release to assess how long a subject could remember the location of the previously lighted bulb. He concluded that the same forms of learning governed rats, dogs and raccoons and found little evidence of mental images. He did report one telling difference: The rats and dogs needed to constantly maintain their bodily orientation toward the lightbulb during the period in which it was off in order to correctly identify it, but the raccoons moved about during the delay. Like the human children, raccoons could identify the correct stimulus even after being distracted.

These results were still not enough to convince Hunter that raccoons possessed human-like reasoning. Hunter accused Cole of anthropomorphism and gullibility when it came to interpreting animal behavior. Cole fired back that Hunter and his students lacked the skills necessary for handling a semi-wild species, preferring instead “toothless” domesticated animals.

Criticisms by Hunter and others gradually pushed raccoons out of the purview of psychologists’ research. Since the 1910s, raccoons have had a few but scattered advocates among psychologists. After 1915, few studies about raccoons appeared in psychology journals. Like many of their generation, Davis and Cole moved from comparative psychology to the field of education. Hunter conducted a few experiments on raccoons over his long career but continued to downplay species-specific traits. With the renewed interest in comparative cognition, perhaps it is time to reconsider the raccoon’s exclusion from the discipline of psychology.


Michael Pettit, PhD, is an assistant professor of psychology at York University, Toronto. Katharine S. Milar, PhD, of Earlham College, is the historical editor of “Time Capsule.”

Suggested reading

  • Cole, L.W. (1907). Concerning the intelligence of raccoons. The Journal of Comparative Neurology and Psychology, 17, 211–261.

  • Davis, H.B. (1907). The raccoon: A study in animal intelligence. The American Journal of Psychology, 18, 447–489.

  • Hunter, W.S. (1913). The delayed reaction in animals and children. Behavior Monographs, 2, 1–86.

  • Pettit, M. (2010). The problem of raccoon intelligence in behaviourist America. British Journal for the History of Science, 43 (3), 391–421.