PSY402 Theories of Learning

1. PSY402Theories of Learning Monday February 24, 2003

2. Two Theoretical Approaches • S-R associative theorists -- inflexible view of behavior. • Mechanistic • Stimulus acquires ability to elicit response through associations formed. • Cognitive theorists – flexible view. • Mentalistic • Learning involves recognition and understanding of environment.

3. Hull’s Drive Theory • Drive motivates behavior and drive reduction is responsible for the S-R associative learning. • Drive – an intense internal force. • Behavior is the combined influence of several factors, which can be expressed mathematically.

4. Hull’s Factors • Excitatory potential (expectation) SER – likelihood that an event will occur. • Drive (D) • Incentive motivation for reward (K) • Habit strength (H) – strength of the S-R association (experience). • Inhibition – also due to experience.

5. Sources of Drives • Unconditioned: • Physiological deprivation, metabolic imbalance. • Intense environmental events with survival consequences. • Pleasurable stimuli (such as saccharin) even without nutritional value. • Acquired – Pavlovian conditioned cues to unconditioned drives.

6. Habit Strength • SUR – an unconditioned or innate habit strength. • SHR – habit strength acquired through prior learning experiences. • If a response reduces a drive state, habit strength increases. • Drive reduction strengthens the S-R bond until behavior becomes habitual.

7. Inhibition • Reactive inhibition -- if a drive persists then all behavior is temporarily inhibited. • Conditioned inhibition – continued failure to reduce drive resulting in a permanent decrease in behavior. • The second strongest response in the habit hierarchy will be performed instead.

8. Incentive Motivation • Hull initially assumed that only drive reduction influences the S-R bond. • Crespi showed that reward magnitude affects responding. • If reward only influenced learning, the change should be more gradual. • Hull proposed that reward also influences motivation by increasing arousal.

9. Importance of Hull’s Theory • THE dominant theory in the 1930s-1960s. • Correct in many respects: • Intense arousal can motivate behavior. • Environmental stimuli can develop the ability to produce arousal, motivating behavior. • Value of the reward influences the intensity of behavior.

10. Problems With Hull’s Theory • You can get increases in behavior without drive reduction: • Olds & Milner, direct brain stimulation • Sensory deprivation motivates behavior to obtain stimulation (Harlow). • Hull’s theory does not explain how secondary rewards can acquire the ability to increase behavior.

11. Drive-Induction Theory • Sheffield -- drive-induction not reduction strengthens behavior. • Rewards produce excitement or arousal which motivates responding. • When secondary rewards are associated with primary rewards they elicit the same arousal. • Also explains Harlow’s findings.