Neo-behaviorism: Taking it to the Limit

Four Key Developments:

1. Tolman introduces “intervening variables”

2. Hull incorporates “biological drives”

3. Thorndike establishes “reinforcement”

4. Skinner goes “operant”

Edward Tolman (1886-1959): Purposive Behavior

• Tolman asserted that Watson’s strict stimulus-response approach to psychology was only a study of “twitches.”

• Believed that environmental events and internal events were both needed to explain behavior.

• Proposing his theory of Purposive Behavior, he believed he could employ stimulus-response methods to study the role of purpose in behavior.– Avoided making inferences of behavior.– To avoid such inferences, he created

“intervening variables,” or operationally defined purposes.

Intervening Variables• Intervening variables reflect the use of

logical positivism in psychology. Rather than assume the meaning of behavior, Tolman created operationally defined purposes for behavior.

• With his love of rats, he developed and employed the now-famous rat mazes. The purpose of the behavior in the maze – to find the food.

• The rat maze was T-shaped. The rat walked up to the decision point, one direction was an exit (food), the other was a dead end (no food).

Intervening Variables (cont.)

• Famous study – He had three groups of rats. Group “A” was given food at their exit, groups “B” and “C” were not given food.

• After 10 days, group “A” showed more signs of learning the maze (fewer errors) than groups “B” and “C”. On the 11th day, he gave group “B” food at the end of the maze. On 12th day, “B” went from acting like “C” (high error) to acting like “A” (low error)

Intervening Variables (cont.)

• These results convinced Tolman that “B” rats had learned the maze, but did not act like “A” rats until they had the same purpose.

• Tolman made internal “intervening variables” – e.g., purpose – compatible with behavioral research.

• Thanks to him, concepts such as “hypothesis,” “confirmation,” “expectation,” “belief,” and “cognitive maps” also became part of behavioral research.

Clark Hull (1884-1952): Hypothetico-Deductive Theory• Expanded on the use of intervening variables, but

opposed all internal (mental) speculations..• Hull replaced “purpose” with biological needs.

– Biological needs created “drives.”– Behaviors which fulfilled the needs

would be reinforced by “drive-reduction.”

– Learning was “habit strength,” or the strength of the connection between a situation and the need-fulfilling (drive-reducing) response.

Hypothetico-Deductive Theory

• Hull’s theory was an effort to create a complete model for learning.

• It is based on the idea of stimulus-organism-response – using intervening variables to represent the organism in the research. – S-O-R, not S-R

• Hull’s theory, however, was very complex. It had 17 universal intervening variables and 133 theorems (rules of behavior).

Hypothetico-Deductive Theory (Cont.)

• “Reaction potential” was one of the more famous and useful theorems, and is commonly used to represent Hull’s theory.

• Reaction potential = “habit strength” x “drive”

– As shown in the textbook, Hull liked to present his theorems as mathematical formulas.

– In this case, the formula states that drives and habits have a multiplicative effect on responses.

Edward Thorndike (1874-1949

• Law of Effect: of several responses made to the same situation– those which are

accompanied or closely followed by satisfaction ….will be more likely to reoccur

– those accompanied or closely followed by discomfort will be less likely to occur

Law of Effect: Basic Points

• Law of Effect• Some randomness to behavior

(variability)• Behaviors that lead to pleasurable

consequences are “stamped in” • Those that have noxious

consequences are weakened.

B.F. Skinner (1904-1990)

• Skinner developed a form of behaviorism which he called “operant” conditioning, which differed fundamentally from the original “classical” conditioning.

• Classical conditioning was based on the ability to add conditioned stimuli to an unconditioned stimulus-response set, resulting in conditioned responses. Operant conditioning was based on the ability to influence responses with rewards and punishments – “reinforcing” responses.

Environment and Behavior

• In the spirit of Darwin, Skinner viewed the environment as “selecting” behaviors, rather than “stimulating” behaviors.

• Environmental influence manifested itself in the form of rewards and punishment for various behaviors.– Rewards could be a desired gain or the loss

of something undesired.– Punishment could be an undesired gain or

loss of something desired.

Reinforcing Behavior• Skinner showed how rewards and

punishment could shape behavior, and showed the varying effects of schedules of reinforcement.– Fixed intervals – e.g., every fifth time– Fixed ratios – e.g., every night, every

Sunday– Variable intervals – after a random

number of times (the gambler’s reinforcement)

– Variable ratios – every now and then

Behavioral Therapy

• Skinner assumed that abnormal behavior was learned, and hence, normal behavior could be learned.

• Therapy, in turn, was viewed as an act of removing the reinforcements of undesirable behavior and providing reinforcements of desirable behavior.

• Behavior therapy has been successful in treating fears, disorders, and unhealthy behaviors.

• A famous example is the “token economy” …

Token Economy

• Skinner’s methods of behavioral reinforcement have been used in institutions for the mentally ill as well as in criminal detention facilities.

• Tokens are given to patients after desirable behaviors, and taken away from patients after undesirable behavior.

• The patients are given the opportunity to use the tokens for a variety of desirable things such as snacks, entertainment, and privacy.

Token Economies

• Institutions using token economies have reported a higher success rate with patients than those without token economies.

• Famous philosophical question – what is the difference between our currency-based economy and a token economy? In other words, how much is money related to (or separate from) behavioral reinforcement?

Behaviorism Encounters Problems

• The decade of the 50’s witnessed a growing dissatisfaction with behaviorism.

• Many behaviorists were becoming disenchanted with overly simplistic and presumably incomplete explanations.

• In the U.S., alternatives to pure behaviorism started with Tolman’s purposeful behavior, but his theory was seen more as a “friendly amendment” than a viable alternative.

• Basically, the limitations of behaviorism were becoming too obvious to ignore.

The Problem of Language

• The biggest problem for behaviorists was not rival theoretical paradigms, but that some real-world activity appear unexplainable by behaviorism.

• For example, behaviorists had problems explaining the acquisition of languages.

• With a primary language (a language learned within the development of language skills), children learn suddenly and holistically.

• With learning a secondary language (after having language skills), though, the learning is more similar to behavioral trial-and-error learning.

The Problem of Language (Cont)

• The behaviorists had problems explaining the acquisition of language, but more importantly, a purely cognitive explanation was becoming a world-renowned theory.

• In 1957, Noam Chomsky presented his first account of the Language Acquisition Devise (LAD). It replaced the grammar-theories of language with a syntax-theory of language.

• In short, Chomsky proposed that we all have an innate mental mechanism that relates sound-patterns with syntactic meanings (the LAD).

Expertise Problems

• In the real world, a novice is relatively slower and less skilled than an expert. With pure behaviorism, though, the vast experiences of the expert are supposed to be a burden.

• Expertise presented a similar problem as those of language acquisition. Experts can mentally do more, and can do it faster.

• A jogger’s analogy … as the expert “learned” to jog longer distances, the expert would finish more quickly each time the distance got longer.