Theories of Reinforcement

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 Compare with Set Point Amount of food in body 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 • Behaviorsare 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 The ice cream scale (in pints) .25 .5 .75 1.0 1.25 1.5 1.75 2.0 2.25 2.5 Will work to obtain Will work to avoid ice cream Bliss point (1.0 pint/night)

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