Edward ChaceTolman A different kind of behaviorist
Another interesting character! • 1886-1959 • Massachusetts born • Quaker: this will play important role in his career • Chastised/censored/fired for his peaceful views • In trouble during McCarthy era for his pacificism
Another interesting character! • A cross between a Gestaltist and a behaviorist • Worked with Koffka • But also embraced a partial behaviorist view • Gestaltism had lasting effect • Rejected much of behaviorism • Thought that they, too, were too reductionistic • “twitchism” – reducing everything to stimuli and reflexes • Pushed for study of molar behavior- the whole, intact behavioral pattern
Molar Behavior • Behavior is purposive: always directed towards some goal • Book: Purposive Behavior in Animals and Men (1932) • Whole behavior has different meaning than smaller units of behavior • Both important to understand • But understand that whole is NOT equal to parts • Whole behavior pattern = behavioral Gestalten
Purposive Behavior • Theory focuses on explaining goal directed behavior • Purposive = descriptive, notnecessarily causal • E.g., searching ends when find food, therefore reason for searching ends when find food • Behavior persists as long as maintaining stimuli is provided by some need state • Behavior “looks as if” goal directed • Little loose with his language • Behaviorist in that focused on observable and overt responses
But why rats? • Liked them! • Easy to use • Easy to control environmental conditions • Known genetic background • Good starting place!
Major theoretical concepts • Several general assumptions: • What is learned = whole patterns of behavior • Reinforcement = confirmation of event • Trial and error may be vicarious; not have to experience it directly • Learning is different than performance • Learning may be latent • Performance more affected by “reward” • Place learning is different than response learning • Learning a “place” versus learning a “response” • Why is this important?
INTERVENING VARIABLES • Instead of an S-R theory, Tolman's= S-O-R theory. • An act of behavior is initiated by environmental stimuli and physiological states. This is processed by the organism, and the response/behavior emerges • Thus: • (S) --(stimulus) the independent variable-- • (0) --(for organism) Certain processes intervene the intervening variable-- • (R) --(response) and Behavior emerges. The dependent variable. • The problem of psychological analysis at the molar level: • to infer the processes which intervene between the initiation of action in the world of physics and physiology and the observable results, again in the world of physics and physiology. • All data are observable, so the system remains a behaviorism. • Intervening variables include • cognitions • Purposes • these are inferred from what the organism does.
SIGN LEARNING • S-R theories imply that • organism goaded along path by internal and external stimuli • Organism learns correct movement sequences so that they are released under appropriate conditions of drive and environmental stimulation. • It learns the "signs" (cues, stimuli) that tell it where it is and where can find reward. • Thus: sometimes called a stimulus-stimulus (SS) theory rather than a stimulus-response theory (SR). • Tolman's Alternative: • learner is following signs to a goal, • Learning way about, following a sort of map • Learning NOT movements but meanings. • Organism learns a behavior route, not a movement pattern.
What is learned? • Traditional behaviorists: • S-R associations= what is learned • Complex learning involves complex combinations of S-R relationships • Tolman: • Learning = process by which organism discovers what leads to what in environment • S-S psychologist • Connecting stimulus events, not necessary responses • Learning requires NO motivation • Drive state may orient/direct behavior towards S-S relationships • Reward = emphasizer or a confirmation of connected events
Cognitive Maps • Cognitive Maps • Picture of environment that animal uses to get around • Can’t look at individual responses, but response patterns = cognitive map • Principle of least effort • Animal will choose shortest route or route requiring least amount of work • Optimizer • Very similar to Hull’s habit family hierarchy • Organism can reach goal through multiple and alternative routes • Argued that first choice = route that requires least effort • Why least effort? Hull said: • Shortest delay to reward (ending drive state) • Greatest amount of SER • Tolman: because of cognitive maps- taking shortest “routes”
Confirmation versus Reinforcement • Some similarity between Tolman’s model and other behaviorists • Confirmation = reinforcement • Hypotheses = tentative expectations • Expectancies that consistently confirmed = means/ends readiness or belief • Confirmation of an expectancy = reinforcement of hypothesis • Cognitive process • Not involve overt things/behaviors/events • if an expectancy is confirmed, its probability value is increases; • if not, its probability value is decreased (i.e. it undergoes extinction) • Tinklepaugh's (1928) study hiding banana under cup. • When a lettuce leaf secretly substituted and the monkey found it, the monkey appeared disturbed, • rejected the lettuce, engaged in search behavior as if looking for the banana. • Many replications of this result • This is different from saying that it cannot play an important role in learning. • One role of motivation: It affects which features of the environment you pay attention to, and therefore what is learned. • He used the term EMPHASIS rather than attention
But what IS the animal learning? • Place learning experiments show learner does not move from start to goal according to a fixed sequence of movements, • Evidence against Watson and Hull • Rather, appropriately vary behavior under changed conditions, • Tolman: looks as though rat “knows” where the goal is. • Cross elevated maze. • The response learning group always found food at right; thus turn right = food • place learning group always at same place. Food = location • Place-learning group learned much faster, and some animals in the response-learning group never learned. • Tolman& Honzik: 3 paths. When shortest was blocked, the went to second shortest. • In “hypothesis testing in rats" Tolman concluded that in a 4-choice maze • the animals adopted systematic modes of solution, • the choices somewhat tentative, so that one mode would be rejected for another if the first one didn't work.
Vicarious Trial and Error • Vicarious trial and error: • When rat stops, searches, and “looks like it is thinking” • Tolman suggested that animal was “thinking of alternatives” in his head • there was vacillation at a choice point before the animal “committed" to a choice. • Tolman interpreted this apparent active comparing of stimuli to support his view that perceptual and cognitive processes have strong roles in learning • This “internal thinking through alternatives” is really, really unverifiable! • Maybe- with current neuroimaging and neurochemistry, may be able to record these behaviors • What is implication? • Does it matter if make overt or covert response? • Suggests trial and error important either way!!!
Learning versus performance • Learning = acquisition of expectancies • Performance = translation of learning into behavior • We know many things about environment • Act on information only when necessary • Information lies dormant until called on to be used • Basic summary • Organism brings to learning situation a set of hypotheses that it may use to solve problem • Hypotheses largely based on prior experience, but may be innate • Hypotheses that survive = best fit with reality, result in goal achievement • After many trials and many reiterations of testing of hypothesis, cognitive map develops • Can be used under altered conditions • E.g., may generalize to similar situations • When a demand/motive is satisfied, organism uses information to add to/adjust cognitve map • Information can be utilized only under certain conditions = basis for distinction between learning and performance
Latent Learning • Latent learning = learning not translated into performance • May remain dormant for some time • Learned, but not manifested as behavior • Tolman’s evidence for latent learning: • Three groups of rats learning to run maze • One group reinforced • One group not reinforced • One group only reinforced after 11th day • Predicted last group would be learning maze, just not have motivation to run it fast!
Several kinds of latent learning experiments: • Unrewarded trials with later introduction of relevant reward. • Tolman& Honzik used a 14 unit multiple T-maze. • The rat couldn't return when it had successfully gone into next segment. • Rats fed at the end did better than those not fed, • but unfed rats had a sharp jump in performance when they started to get fed. • Free exploration followed by reward = faster performance • Location of incentives learned under satiation and tested under relevant drive. • Location of incentives learned under strong irrelevant drives. • pointed to the role of attention. • If a rat was thirsty, for example, it was not so good at learning the cues that told where food was. • infer that it was paying attention to cues that told where water was, • the strong direction of its attention toward finding water interfered with becoming aware of where the food was
Tolman and Honzik's (1930b) data showing the average number (with a constant multiplier) of blind alleys each day for rats receiving food at the end of the maze from the 1st day of the experiment (hungry rewarded, HR), rats not receiving food at the end of the maze for the entire experiment (hungry nonrewarded, HNR), and rats receiving food beginning on Day 11 and continuing until the end of the experiment (hungry nonrewarded-rewarded, HNR-R).
Latent Learning • Three things emerge from data: • Slight improvement in performance even when never explicitly reinforced • Reinforced group shows steady improvement throughout experiment • When reinforcement introduced for group 3, performance vastly improved • Why- • Tolman says was learning the whole time, just not motivated to run • Could be that finishing the maze was mildly reinforcing? • Do you ever engage with stimuli in absence of reward?
Latent Extinction • Reinforcement theorists: Extinction = active process • Previously reinforced response must not be reinforced • Learning different contingency • Rate of responding should return to baseline (pre reinforcement) levels • Not so for Tolman • Learning occurs separate from reinforcement • If animal simply observes S-S connection no longer results in food, then can learn (extinguish) vicariously • E.g., if placed into empty goal box, even without running maze • Why ? • Motivational factors = causal (Spence) • Reward = incentive; no incentive, no behavior • Remember, can chain up secondary reinforcers
The debate over expectancy versus habit • Tolman’s view characterized as a "what leads to what" theory • a theory of signs • guideposts, and behavior roots. • With repeated experiences: • Probability learned that the given behavior will lead to the expected end result. • The result is faster running and elimination of going down blind alleys exactly as if a habit were being strengthened by reward. • Not so easy to distinguish between these two views. • The latent learning experiments were crucial here • If it was habits, then no latent learning!