Schedules and more Schedules

Schedule of Reinforcement -- Terminology Contingency Causal Relationship between a response and the reinforcer (R) - (O) doing (R) produces (O) Schedule of Reinforcement: Rule determining the response reinforcer relationship, the contingency Sometimes contingency is not 1:1, sometimes doing(R) does not produce (O) Pressing remote control button to turn on the TV Schedule Effects: Refers to the pattern and rate of performance produced by a particular reinforcement schedule The pattern of buttons pushing Particular kind of reinforcement schedule tends to produce a particular pattern and rate of performance Rate of Responding How fast the responses are made Slope of the line on a Cumulative Recorder Mechanical recording equipment use by Skinner to study schedules See Figure 6.1

Figure 6.1 – The construction of a cumulative record by a cumulative recorder for the continuous recording of behavior. The Principles of Learning and Behavior, 7e by Michael Domjan Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.

Schedules of Reinforcement Continuous Reinforcement (CRF) Behavior is reinforced every time it occurs 1:1 Examples: Rat gets food pellet every time it presses lever Children praised each time they hang up their coats Leads to rapid increases in the rate of behavior Not very common in natural environments (including humans) Intermittent Schedules Behavior that is reinforced on some occasions but not others 2 main categories Ratio – reinforcement depend on number of responses Fixed: number of responses to get reinforcer stays the same Variable: number of responses to get reinforcer varies Interval – reinforcement depend on responses and amount of time passed Fixed: amount of time is fixed Variable: amount of time varies See Figure 6.2

The Principles of Learning and Behavior, 7e by Michael Domjan Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.

Fixed Ratio (FR) Schedule A fixed number of responses to get reinforced Indicated by letters FR followed by number of required responses FR4 requires four response FR10 requires ten responses CRF is technically an FR 1 Type of behavior pattern produced see Figure 6.2 CRF produces a mostly steady moderate rate of responding Higher FR schedules produce a pause after the reinforcer is delivered Post-Reinforcement Pauses (PRP) Pause occurs after the reinforcer is delivered Occurs in anticipation of making the next set of responses Examples “Piecework” Paid by number of items produced Mowing lawns, washing cars, writing a research paper

Post-Reinforcement Pauses (PRP) Average size of PRP increases as size of ratio increases Example: FR 40 may have PRP of 3 seconds, but FR 130 = PRP 6 seconds most noticeable at high FR Ratio Run is the burst of responding to get the next reinforcer Rate of responding once responding starts stays fairly constant regardless of ratio size Run Rate for FR5 same as FR10 Ratio strain: With a large increase in the ratio requirement can produce pauses during the ratio run or stop responding altogether Procrastination related pause before starting a task

Variable Ratio (VR) Schedule A variable number of responses to get reinforced Indicated by letters VR followed by average number of required responses VR4 requires four response on average 2 , 5, 3, 6, 4 responses requires but average rate is 4 VR10 requires ten responses on average Type of behavior produced: see Figure 6.2 Steady rates of performance at rates similar to comparable FR schedules Absence of long post-reinforcement pauses (PRP) Some small PRPs do occur Examples Salesperson working on commission Games of chance

Fixed Interval (FI) Schedules Fixed amount of time before the reinforcer is available “setup time” Indicated by FI followed by time interval FI 2min: reinforcer is available after 2 minutes 2 minutes starts counting down after delivery of the reinforcer After 2 minutes the next response will produce the reinforcer Type of behavior produced: see Figure 6.2 Pattern referred to as fixed-interval scallop Like FR, there is a PRP Unlike FR start responding slowly and as time passes, rate of responding increases hence the scallop pattern Because of keeping track of the fixed interval Rate of responding increases in anticipation of the interval ending Examples behavior of students studying for a scheduled exam going to the bus stop to catch a bus

Variable Interval (VI) Schedules Variable amount of time before the reinforcer is available Indicated by VI followed by the average time interval VI 4min: reinforcer is available on average after 4 minutes Series of 2 min, 5min, 3min, 6min, 4min intervals that average to 4min After the time interval the next response will produce the reinforcer Type of behavior produced: see Figure 6.2 Steady, moderate rate of responding Examples: Sales clerk waiting for customers Predators waiting for prey Limited Hold With interval schedules usually reinforcer remains available forever Under limited hold conditions the reinforcer is available for a set time and then disappears For example food service at the cafeteria

Comparing VR and VI response rates VR schedules produce higher response rates than VI schedules. One possibility: Response rate higher when reinforcement rate (reinforcer per min) is higher. Will VR still produce higher response rate if rate of reinforcement is equated on both schedules?

Comparing VR and VI response rates Reynold’s (1975) Experiment See Figure 6.3 Compared responses on a VI schedule yoked to a VR schedule One pigeon reinforced on VR schedule One pigeon on VI yoked to a pigeon on VR when the pigeon on VR was one response short of the VR requirement, the next response by both birds produced food. food availability depended on the time it took the VR bird to complete its response requirement. this time interval varied from one reinforcer to the next (dependent on # of responses the VR bird had to make and how long it took the VR bird to make them). Both birds received food at approximately the same time, and therefore the rate of reinforcement (i.e., reinforcers per min) was the same for both birds. Despite the effort to equate rate of reinforcement, the VR bird pecked much more rapidly than the VI bird. Thus, differences in reinforcement rate do not account for the differences in response rate Replicated using students playing a video game (Raia 2000)

The Principles of Learning and Behavior, 7e by Michael Domjan Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.

Comparing VR and VI response rates Interresponse Time (IRT) Reinforcement Theory A better way to explain the difference in response rates between ratio and interval schedules is based on the Inter-response time (IRT) – the interval, or pause, between responses On variable interval schedules the probability of reward increases with slow responding which is a longer IRTs On a VI schedule, long IRTs are more likely to be reinforced, thus less rapid responding is reinforced. On variable ratio schedules A low response rate increases duration to the next reward On a VR schedule, short (IRTs) are more likely to be reinforced, thus rapid responding is reinforced. So interval schedules reinforce slower responding while ratio schedules reinforce faster responding

Comparing VR and VI response rates Feedback Functions Feedback function takes into account the consequence of making responses over a long period of time Ratio schedules have a direct relationship between responses and reinforcement if on a VR 20 schedule responding twice as fast produces twice as many reinforcers for example with "piece work" you can increase income by working faster Interval schedule have an indirect relationship between responses and reinforcement if on a VI 30 second schedule responding twice as fast does not change rate of getting reinforcers for example salaried (hourly) employees can not increase their income by working faster

Procrastination To voluntarily delay an intended course of action despite expecting to be worse-off for the delay Major causes of procrastination Personal Traits: Self-Efficacy, Energy, Impulsiveness & Self-Discipline, Achievement Motivation Task Characteristics: Aversiveness We seek to avoid aversive stimuli, and consequently, the more aversive the situation, the more likely we are to avoid it (e.g., procrastinate). People who find tasks aversive, tend to be procrastinators Explanations for procrastinating writing a term paper is simple, “Really dislike writing term papers.” Task Characteristics: Delay The further away an event is temporally, the less impact it has upon our decisions Students indicate that they are less likely to procrastinate as a deadline approaches

Procrastination Management Break a big task into smaller series of tasks Reduces PRP Set rewards for completing a task Set consequences for not completing the task can be effective as long as they are attached to a deadline. personal contract with a penalty pay $100 for missing the deadline