Schedules of Reinforcement Thomas G. Bowers, Ph.D.

How is behavior maintained? b Simplistic to simply think uncomplicated contingencies operate in the day to day environment b Patterns of reinforcement, patterns of conditioning, relate in a complex fashion with the characteristics of the organism

Schedules of Reinforcement b Yield predictable and orderly patterns of behavioral responses b Most patterns of reinforcement are intermittent b More recently, theorists have also attended to the economic aspects of intermittent reinforcement

Schedules of Reinforcement b Basic Schedules 1. Fixed Interval Schedules (FI)1. Fixed Interval Schedules (FI) –A single response after the passage of a fixed period of time yields reinforcement –Responses during the interval are not reinforced 2. Variable Interval Schedules (VI)2. Variable Interval Schedules (VI) –A single response after a varied passage of time –e.g. VI2 - after an average passage of 2 minutes

Schedules of Reinforcement b Basic Schedules 3. Fixed Ratio (FR)3. Fixed Ratio (FR) –Reinforcement occurs after a fixed number of responses –Passage of time irrelevant 4. Variable Ratio (VR)4. Variable Ratio (VR) –Number of responses required for reinforcement vary from trial to trial –e.g. VR 50 reinforces on the average the 50th response

Schedules of Reinforcement b Intermittent reinforcement tends to maintain patterns of responding for longer periods of time in extinction partial reinforcement effectpartial reinforcement effect implies greater response strengthimplies greater response strength

Schedules of Reinforcement Cumulative Responses Time VR VI

Schedules of Reinforcement Cumulative Responses Time FR FI

Schedules of Reinforcement b Some characteristics 1. Variable schedules tend to develop higher rates of responding relative to fixed schedules1. Variable schedules tend to develop higher rates of responding relative to fixed schedules 2. Ratio schedules tend to develop higher rates of responding to interval schedules2. Ratio schedules tend to develop higher rates of responding to interval schedules 3. Fixed schedules of reinforcement demonstrate a characteristic pause after each reinforcement3. Fixed schedules of reinforcement demonstrate a characteristic pause after each reinforcement

Schedules of Reinforcement b Some characteristics 4. Pause of responding after reinforcement on fixed ratio/interval is described as post- reinforcement pause (PRP)4. Pause of responding after reinforcement on fixed ratio/interval is described as post- reinforcement pause (PRP)

Choice Behaviors b Study of Concurrent Patterns of Reinforcement How is behavior demonstrated in the situation where there are multiple schedules of reinforcement operating?How is behavior demonstrated in the situation where there are multiple schedules of reinforcement operating? Organisms respond in direct proportion of the frequency (or density) of reinforcement offeredOrganisms respond in direct proportion of the frequency (or density) of reinforcement offered

Matching Law b Herrnstein and associates in the 1970s Respon A Respon A + Respon B = Rft A Rft A + Rft B

Matching Law b Or, more clearly RA RA + RB = ra ra + rb

Matching Law b Magnitude of reinforcement Ra Ra + Rb = Ma Ma + Mb

Matching Law b Delay of Reinforcement Ra Ra + Rb = 1/Da 1/Da + 1/Db

Matching Law b Allows for more complex processing analysis Ra Ra + Rb = ra x Ma x 1/Da (ra x Ma x 1/Da) + (rb x mb x1/Db)

Matching Law b Animals tend to respond differentially, with more responses to the smaller immediate reward relative to the larger delayed reward

Choice Behaviors Choice Behaviors b Immediacy of reinforcement can “lock in” an organism to a leaner schedule of reinforcement

Matching and Maximizing b Maximizing suggests the animal will demonstrate the response which maximizes the likelihood of reinforcement b This is somewhat different than predicted by matching predictions

Matching and Maximizing b Animals tend to distribute responses in relation to the density of reinforcement b This is even true when some patterns results in less over all reinforcement

Matching and Maximizing b This effect has been attempted to be explained by optimal foraging theory b Feeding behavior is thought to be sensitive to the amount of energy expended in finding, securing and eating food b There may be adaptive significance to seeking varieties of food sources

Economic Concepts b Demand Some demands are elasticSome demands are elastic Others are inelasticOthers are inelastic For example, bread is probably inelastic, while movies may be elasticFor example, bread is probably inelastic, while movies may be elastic

Types of Economies b Open versus closed contingent systems open systems tend to decrease response ratesopen systems tend to decrease response rates holds for both FR and VR schedulesholds for both FR and VR schedules

Summary b Intermittent schedules of reinforcement leads to greater response strength b Variable schedules of reinforcement yields higher levels of behavior b Ratio schedules of reinforcement also yield higher levels of behavior b Interval schedules demonstrate characteristic patterns of responding

Summary b Organisms tend to match reinforcement probabilities rather than maximize reinforcement b Economic aspects influence patterns of contingent behavior