Edward Chase Tolman (1886-1959)

Edward Tolman was born in West Newton, near Boston. His family was wealthy but espoused simple values derived from a Quaker heritage. Tolman graduated from the Massachusetts Institute of Technology. After, influenced by working with Yerkes and having read James, he decided to pursue graduate study of psychology at Harvard. There he noticed a disjoint between his lecture and laboratory classes. In the laboratory his teachers used objective methods while in class they still lectured about introspection. Tolman was an early convert to Watson’s behaviorism and later reported personal relief at being able to leave introspection behind. Unlike many American psychologists of his generation, Tolman went to Europe to study. He spent a year in Germany studying with the Gestalt psychologist Kurt Koffka. Tolman was one of the few American psychologists to incorporate theoretical explanations from Gestalt psychology (see chapter 12) into behaviorism. In 1918 he began to teach at the University of California at Berkeley, where he remained throughout his long career.

FYI: Tolman and the California Loyalty Oath-Late in his career, at the height of McCarthyism, Tolman refused to sign a loyalty oath to the state of California. In a lawsuit that followed he successfully defended his position and the law was struck down. When I became a graduate teaching assistant in 1976 I had to sign a loyalty oath to the state of Louisiana. Unlike in California, the Louisiana loyalty oath continues to be required of all state employees.

Tolman began a research program that quickly added many new concepts to the emerging neobehaviorist school. He wanted to divorce psychology from its close dependence on physiology while at the same time seeking a better theoretical structure for neobehaviorism. One of his first contributions was to redefine behavior itself into two categories: molecular and molar. Molecular behaviors were closely linked to physiology (e.g., muscle contractions or glandular secretions). Molar behaviors, on the other hand, were of a larger scale. Examples of molar behaviors included maze learning (whether running it, swimming it, or wading through it) and driving home from work (regardless of the route taken). Interestingly, Tolman argued that molar behaviors could be studied of themselves, without reference to any underlying physiological mechanisms. Tolman’s approach was a far cry from Watson’s earlier appeal for a tight linkage between behavior and physiology.

Tolman popularized the use of the white rat in psychology. Using mazes of varying types, he and his students discovered a number of cognitively based phenomena including expectancies and cognitive maps. One of them (Tinklepaugh 1928), using a delayed reaction task, demonstrated that monkeys reacted negatively when they were shown a banana being hidden under a cup but discovering that lettuce had been substituted there in their absence. As a control, Tinklepaugh had also left the lettuce hidden and untouched in other trials. Here is his description of the monkey’s reactions (p. 229) during the control (a) and experimental conditions (b):

(a) Subject rushes to proper cup and picks it up. Seizes lettuce. Rushes away with lettuce in mouth, paying no attention to other cup or to setting. Time, 3–4 seconds.

(b) Subject rushes to proper cup and picks it up. Extends hand toward lettuce. Stops. Looks around on floor. Looks in, under, around cup. Glances at other cup. Looks back at screen. Looks under and around self. Looks and shrieks at any observer present. Walks away, leaving lettuce untouched on floor. Time, 10–33 seconds.

He and Tolman interpreted these results as evidence that the monkey expected lettuce in the control condition and received it but expected a banana in the experimental condition and received lettuce instead. They interpreted the monkey’s different reaction in each case as behavioral evidence of different cognitive states. Tolman believed he had demonstrated an expectancy in a non-human animal.

Marginal Definition: expectancy-an internal state in which an organism anticipates an event based upon prior learning trials.

One of Tolman’s most famous contributions was the cognitive map, a concept he derived from Gestalt psychology. In a series of experiments, Tolman and his co-workers demonstrated that rats learned the spatial relationships between themselves and a food item. After learning an initial forced roundabout relationship in a maze between themselves and food located in a specific place, rats would successfully choose a new path in a different maze but one in which the food was in the same place it had been in the previous maze. That new path, usually, was a direct line to the food item. To Tolman, that indicated that the rats knew where the food was located in a cognitive map that they carried in their heads. He wrote describing one of his studies (Tolman, 1948, p. 204) “the rats in this experiment had learned not only to run rapidly down the original roundabout route but also, when this was blocked and radiating paths presented, to select one pointing rather directly towards the point where the food had been.” Figure 11.1 shows the two mazes used in that study (Tolman, Ritchie, & Kalish, 1946).

----------Insert Figure 11.1 about here[Tolman, Ritchie, and Kalish mazes]----------

FYI: Your Cognitive Maps-You have probably noticed that you possess detailed and accurate cognitive maps of your preferred routes to class or to the nearby stores. But, your cognitive maps for places you seldom visit are more fuzzy and inaccurate. Tolman would argue that your cognitive maps develop with experience. The more experience you have, the better your map, he thought. Figure 11.2 shows an old New Yorker cartoon in which there are two very different cognitive maps of the same area. The policeman’s map is very clear while the tourist’s is not.

---------------Insert Figure 11.2 about here[Cognitive Map cartoon]---------------

Another famous concept of Tolman’s was latent learning. That line of research led to his distinction of the differences between learning and performance. Following earlier work in his laboratory, Tolman and Honzik (1930) decided to investigate whether learning required a reinforcer (food, in this case). They trained three groups of rats in the same complex maze using the average number of errors per trial as the criterion for learning. Those errors should drop over time, exhibiting a classic learning curve. One group, the control, was never fed. Another group was always fed, and the final group was only fed after the 11^th day of training. If learning required a food reinforcer, then that last group should begin learning the maze only after commencing to eat on the 11^th day. That is not what happened. Instead once the last group began to be fed, their errors dropped precipitously. Tolman and Honzik interpreted these data by saying that those rats had already learned the maze but that it took the presence of food in the goal box for them to perform or to demonstrate their learning. They called the phenomenon latent learning because the learning, they argued, had already taken place. They argued that the new presence of the food reinforcer now changed the situation causing their errors to go down accordingly. In their theorizing reinforcement was not necessary for learning.

Then and Now: Latent Learning and Cognitive Maps-Jensen (2006) notes that nearly all of the general psychology textbooks he surveyed gave incomplete and misleading accounts of the current status of latent learning and cognitive maps. The history of latent learning shows that “There was no resolution at all...it became clear...that...no empirical solution was likely” (p. 195). He argues that most current textbooks do not tell students that the issue of latent learning was essentially abandoned. He also discusses Tolman’s cognitive map metaphor in the light of subsequent research and writes, “although the cognitive map metaphor might retain its appeal, a close examination...exposes substantial weaknesses (p. 204). Ultimately, Jensen is concerned with the pervasive effect of historical misinformation upon new psychology students.

Tolman created a viable neobehaviorist alternative to Watson’s earlier scheme. To do so, Tolman endowed his rats (and, by extension, people) with intervening variables

Marginal Definition: intervening variable- unobservable variables such as internal states or cognitions assumed to influence behavior.

or variables that lay between a physical stimulus and an observable behavior. Those intervening variables were the actual cause of the behavior but were unobservable. Yet, they were still amenable to experimental analysis via the doctrine of operationism that

Marginal Definition: operationism-the idea that science is best understood as a public, operationally defined enterprise in which phenomena may only be analyzed via methods that yield concrete results.

had come to psychology via physics. One of the best examples of a psychological intervening variable is hunger. To an old-time introspective psychologist, hunger would be an aspect of consciousness, a kind of feeling. However, no one could estimate or compare degrees of hunger made by different hungry people using introspective methods. Tolman (and nearly all psychologists since) operationalized hunger by providing descriptions of how to obtain hunger, namely by withholding food. Thus, a rat that had not eaten for 12 hours was hungrier than one that had not eaten for 6 hours. Operational definitions allowed neobehaviorists to describe internal states without using introspection.

Border with Computational Science: Modern Physics-The many discoveries in modern physics leading up to the development of the atomic bomb also required the use of operationism. For instance, the many sub-atomic particles created by bombarding the nuclei of atoms were first described as intervening variables. Many experiments were run to determine if those unseen particles actually existed. Those particles that followed the paths predicted by atomic theory were deemed to exist despite never being actually observed themselves. The rise of modern physics occurred at around the same time as the emergence of neobehaviorism and influenced it markedly. In psychology, the intervening variables that predicted particular behaviors were also viewed as real despite being unobservable. Percy Bridgman, a physicist and the author of an influential book, The Logic of Modern Physics (1928), was partly responsible for leading psychologists to imitate physicists. During the 20^th century physics was the quintessential model for how any science should operate and most psychologists aspired to make their science resemble it.

Tolman created a liberal compromise between the introspective methods of the past and Watson’s extreme behaviorist position. In place of S-R theory, he introduced S-S (stimulus-stimulus) theory. Learning, for Tolman, was all about the relationships between stimuli, not the response to a given stimulus. His position, however, was too close to the older kind of psychology for many psychologists. Clark Hull, in particular, became Tolman’s main theoretical rival. Hull, too, sought to remedy the problems of Watson’s behaviorism. His solution was to keep Watson’s central idea intact; behavior could be controlled and predicted using without any reference to cognitive concepts such as expectancies or cognitive maps. He tried to explain learning via a complex and ambitious overarching theory full of mechanistic variables.