1. Theories of Reinforcement Why is a reinforcer effective? Why do reinforcers increase the probability of a response?

2. Some Early Definitions Empirical: Stimuli that increase the probability of a preceding response are reinforcers –circular definition, after the fact –better, if shown to be trans-situational Theoretical: Reinforcers are stimuli that produce “a satisfying state of affairs” –vague

3. Drive Reduction Theory Organisms attempt to maintain physiological equilibrium (homeostasis) Deviations from homeostasis produce biological drives –examples: hunger, thirst, pain Reinforcers are events that reduce biological drives –examples: Kraft dinner for a hungry undergraduate

4. Drive Reduction Theory Amount of food in body Compare with Set Point Seek or don’t seek food drives

5. But…………….. Sensory reinforcers: Inquiring minds want to know Some reinforcers actually increase drive states Behavior itself might be reinforcing

7. Premack Principle Behaviors are reinforcing, not stimuli To predict what will be reinforcing, observe the baseline frequency of different behaviors Highly probable behaviors will reinforce less probable behaviors

8. Implications Reinforcers are individualized (not intrinsic to the reinforcer itself) Reinforcers are reversible

11. Some Problems With Premack’s Principle Quantification –Some activities naturally take more or less time than others Opportunities to engage in a restricted (but not lower probability) behavior may act as a reinforcer

12. Newer View Timberlake’s Response deprivation hypothesis –reinforcers are responses that have been “deprived”

13. Response deprivation hypothesis.25.5.75 The ice cream scale (in pints) 1.01.251.51.7 5 2.02.252.5 Bliss point (1.0 pint/night) Will work to avoid ice cream Will work to obtain

14. Response Deprivation Hypothesis Low frequency behaviors can reinforce high frequency behaviors All behaviors have a preferred frequency or behavioral bliss point Deprivation below that frequency is aversive, and organisms will work to remedy this

15. Behavioral Regulation Measure time spent in behavior when there is no constraint – behavioral bliss point Schedule imposes a constraint –schedule line Time spent in behavior under a constraint will minimize distance from bliss point

16. The behavioral bliss point and motivation

17. The labor supply curve Amount of Work Amount of reward Bliss point 2 rewards per unit 1 reward per unit ¼ reward per unit