In 1936, he was hired as vice-president of another agency, William Esty and Company. He devoted himself to business until he retired ten years later. He died in New York City on September 25, 1958.

Clark Hull

Clark Leonard Hull was born May 24, 1884 near Akron, New York, to a poor, rural family. His was edu-cjtttnd in a one-room school house and even taught there от year, when he was only 17. While a student, he had a lininli with death from typhoid fever.

I In wont on to Alma College in Michigan to study mining JUiglnoering. He worked for a mining company for two ниш! I im when he developed polio. This forced him to lyult Cor ix I ohm strenuous career. For two years, he was in (inipul of the нате school he had gone to as a child — ttMWi im nd»it lug of two rooms. He read William James and ■hvimI up his money to go to the University of Michigan.

Рая г II

Unit 4

After graduating, he taught for a while, then went on the the University of Wisconsin. He got his PhD there in 1918, and stayed to teach until 1929. This was where his ideas on a behavioristic psychology were formed.

In 1929, he became a professor of psychology at Yale. In 1936, he was elected president of the АРА. He published his masterwork, Principles of Behavior, in 1943. In 1948, he had a massive heart attack. Nevertheless, he managed to finish a second book, A Behavior System, in that same year. He died of a second heart attack May 10, 1952.

Hull's theory is characterized by very strict operation-alization of variables and a notoriously mathematical presentation. Here are the variables Hull looked at when conditioning rats:

Independent variables: S, the physical stimulus.

Time of deprivation or the period and intensity of painful stimuli.

G, the size and quality of the reinforcer.

The time delay between the response and the rein-forcer.

The time between the conditioned and unconditioned stimulus.

N, the number of trials.

The amount of time the rat had been active.

The intervening variables:

S, the stimulus trace.

V, the stimulus intensity dynamism.

D, the drive or primary motivation or need (dependent on deprivation, etc.).

K, incentive motivation (dependent on the amount or quality of reinforcer).

J, the incentive based on delay of reinforcement.

SHr, habit strength, based on N, G (or K), J, and time between conditioned and unconditioned stimulus.

Ir, reactive inhibition (e.g. exhaustion because the rat had been active for some time).

Sir, conditioned inhibition (due to other training).

SLr, the reaction threshold (minimum reinforcement required for any learning).

SOr, momentary behavioral oscillation — i.e. random variables not otherwise accounted for.

And the main intervening variable, sEr, excitatory potential, which is the result of all the above...

sEr = VxDxKxJx sHr - sir - Ir - sOr - sLr.

The dependent variables: Latency (speed of the response). Amplitude (the strength of the response). Resistance to extinction. Frequency (the probability of the response. All of which are measures of R, the response, which is n function of sEr.

The essence of the theory can be summarized by say-Ing that the response is a function of the strength of the 11j 11>i I times the strength of the drive. It is for this reason i li.il. I lull's theory is often referred to as drive theory.

Hull was the most influential behaviorist of the the 11110':; and 50's. His student, Kenneth W. Spence, main-! щи (I I hat popularity through much of the 1960's. But (hi theory, acceptable in its abbreviated form, was too Unwieldy in the opinion of other behaviorists, and could Itol '.illy generalize from carefully controlled rat experi-

I i to the complexities of human life. It is now a mat-

1 I ^{nf historical interest only.}

£. С. Tolman

A very different theory would also have some popularity before the behaviorism left the experimental scene to the cognitivists: The cognitive behaviorism of Edward Chase Tolman. E. C. was born April 14,1886 in Newton, Mass. His father was a businessman, his mother a housewife and fervent Quaker. He and his older brother attended MIT. His brother went on to become a famous physicist.

E. C. was strongly influenced by reading William James, so in 1911 he went to graduate school at Harvard. While there, he spent a summer in Germany studying with the Kurt Koffka, the Gestalt psychologist. He received his PhD in 1915.

He went off to teach at Northwestern University. But he was a shy teacher, and an avowed pacifist during World War I, and the University dismissed him in 1918. He went to teach at the University of California at Berkeley. He also served in the OSS (Office of Strategic Services) for two years during World War II.

The University of California required loyalty oaths of the professors there (inspired by Joseph McCarthy and the «red scare*). Tolman led protests and was summarily suspended. The courts found in his favor and he was reinstated. In 1959 he retired, and received an honorary doctorate from the same University of California at Berkeley. Unfortunately, he died the same year, on November 19.