Chapter 7 - Schedule and Theories of Reinforcement

Schedule of Reinforcement

Response requirement that must be met to obtain reinforcement

-What exactly must be done for the reinforcer to be delivered

Continuous Reinforcement Schedule

A schedule in which each specified response is reinforced

-useful when a behaviour is being first shaped or strengthened

Intermittent (or partial) Reinforcement Schedule

A schedule in which only some responses are reinforced

-Four types; Fixed ratio, variable ratio, fixed interval, and variable interval

Steady State Behaviour

Stable pattern that emerges once the organism has had considerable exposure to the schedule

Fixed Ratio Schedule

Reinforcement is contingent upon a fixed, predictable number of responses

-Every 10 responses = food (FR 10 schedule)

-Every 5 responses = food (FR 5 schedule)

An FR1 schedule is a continuous reinforcement schedule

Generally produces a high rate of response with a short pause following attainment of each reinforcer (post-reinforcement pause)

Ex; Dog pulls lever 10 times, gets food, moves around, then resumes the 10 responses

Creates a “break-and-run” pattern; short break followed by a steady run of responses

Dense vs Lean in Fixed Ratio Schedules

Schedules with easy to obtain reinforcers are dense, while those with more difficulty obtaining reinforcers are lean

-Ex; FR5 is more dense than FR10

Moving from a low ratio requirement (dense schedule) to a high ratio requirement (lean schedule) should be done gradually

Ratio Strain - disruption in responding due to an overly demanding response requirement

Variable Ratio Schedule

Schedule in which reinforcement is contingent upon a varying, unpredictable number of responses

-Organism on a VR5 schedule has to emit an average of 5 responses

-Generally produces a high and steady rate of response, with little to no post-reinforcement pause

Ex; only some acts of politeness may receive acknowledgement

VR helps account for maladaptive behaviours like gambling, and may facilitate development of an abusive or exploitive relationship

-Similar to FR, an extremely lean VR schedule can lead to ratio strain

Fixed Interval Schedule

Reinforcement is contingent upon the first response after a fixed, predictable period of time

-FI 30 seconds = 30 second interval after a response

Produces a “scalloped” (upwardly curved) pattern of responding, consisting of a post-reinforcement pause followed by a gradually increasing rate of response as the interval draws to a close

Pure FI schedule = any response during the interval is irrelevant

Variable Interval Schedule

Reinforcement is contingent upon the first response after a varying, unpredictable period of time

Ex; rat on a VI 30 second schedule, first lever press after an average interval of 30 seconds results in a food pellet

Produces a moderate, steady rate of response often with little or no post-reinforcement

Ex; checking our phone periodically is maintained on a VI schedule

Because VI schedules produce steady and predictable rates, they are used to investigate other aspects of operant conditioning

Comparing FR/VR/FI/VI Schedules

FR/VR produce higher rates of response than interval schedules FI/VI

-Rapidity that responses are emitted does affect how soon the reinforcer is obtained

FI = Increasing response rate, VI = moderate response rate

-Only FR/FI have post-reinforcement pauses

Duration Schedule

Reinforcement is contingent on performing a behaviour continuously throughout a period of time

-Duration schedules are more imprecise compared to the four basic schedules

-Additionally, reinforcing the mere performance of a behaviour may decrease intrinsic motivation

Fixed-Duration Schedule

Reinforcement is contingent upon continuous performance of a behaviour for a predictable period of time

Ex; rat must run for 60 seconds for one pellet of food (FD 60 seconds)

Variable Duration (VD) Schedule

Reinforcement is contingent upon continuous performance of a behaviour for a varying, unpredictable period of time

Ex; rat must run for an average of 60 seconds, with the amount of time required varying between 1 and 120 seconds (VD 60 sec)

Response Rate Schedule

Reinforcement that is directly contingent upon the organism’s rate of response, three types:

1. Differential reinforcement of high rates

2. Differential reinforcement of low rates

3. Differential reinforcement of paced responding

Differential Reinforcement of High Rates

Reinforcement is contingent upon emitting at least a certain number of responses in a certain period of time; reinforcement is provided for responding at a fast rate

-Requiring lots of responses in a short period of time → DRH schedules ensure high rate of responses

Ex; rat gets food if emits at least 30 responses within one minute

Differential Reinforcement of Low Rates

Minimum amount of time must pass between each response before the reinforcer is delivered — reinforcement is provided for responding at a slow rate

Differential Reinforcement of Paced Responding (DRP)

Reinforcement is contingent upon emitting a series of responses at a set rate — reinforcement is provided for responding neither too fast nor too slow

Noncontingent Schedules of Reinforcement

Reinforcers is delivered independently of any response

-Also known as a response-independent schedule

-May account for some forms of superstitious behaviours

• Athletes and gamblers are particularly susceptible to this

• But it may also develop as a by-product of contingent reinforcement

-Superstitious behaviours are most likely to develop on a VT schedule of reinforcement

Fixed Time (FT) Schedule

Reinforcer is delivered following a fixed, predictable period of time, regardless of the organism’s behaviour

-Ex; every 30 seconds = food, regardless of behaviour

Variable Time (VT) Schedule

Reinforcer is delivered following a varying unpredictable period of time, regardless of the organism’s behaviour

Ex; receive food after an average of 30 seconds, ranging from 1 to 60 seconds per trial

-Rainfall follows a VT schedule