Schedules and Theories of Reinforcement Notes

Schedules and Theories of Reinforcement

Types of Positive Reinforcement

• Positive reinforcement can be further distinguished by:

  • Immediate vs. delayed

  • Primary vs. secondary

  • Intrinsic vs. extrinsic

  • Natural vs. contrived

Immediate vs. Delayed Reinforcement

• The more immediate the reinforcer, the stronger its effect on the behavior.

• Example:

  • Giving a treat to a child who is playing quietly while she is still playing quietly reinforces quiet playing.

• The benefits of exercise and proper eating are delayed and therefore weak.

Primary Reinforcers

• A primary reinforcer is an event that is innately reinforcing.

• Examples:

  • Food, water, proper temperature, sexual contact.

Secondary Reinforcers

• A secondary reinforcer is an event that is reinforcing because it has been associated with some other reinforcer.

• Examples:

  • Good marks, fine clothes, a nice car.

• Conditioned stimuli that have been associated with appetitive unconditioned stimuli (USs) can also function as secondary reinforcers.

• Example:

  • A metronome that has been associated with food can be a secondary reinforcer for the operant response of lever pressing.

Generalized Reinforcer

• A type of secondary reinforcer that has been associated with several other reinforcers.

• Example:

  • Money is associated with food, clothing, furnishings, entertainment, and even dates.

  • Social attention is associated with food, play, and comfort.

• A “token economy” is when tokens are given as reinforcers. The tokens can be traded for other rewards later.

Intrinsic Reinforcement

• Reinforcement provided by the mere act of performing the behavior.

• Examples:

  • Rollerblading is invigorating.

  • Attending parties is fun.

Extrinsic Reinforcement

• The reinforcement provided by some consequence that is external to the behavior.

• Examples:

  • You drive to get somewhere.

  • You work for money.

  • You date an attractive individual merely to enhance your prestige.

Natural Reinforcers

• Reinforcers that are naturally provided for a certain behavior.

• They are a typical consequence of the behavior within that setting.

• Examples:

  • Money is a natural consequence of selling merchandise.

  • Gold medals are a natural consequence of hard training and a great performance.

Contrived Reinforcers

• Reinforcers that have been deliberately arranged to modify a behavior.

• They are not a typical consequence of the behavior in that setting.

• Examples:

  • Turning on the television is a contrived reinforcer for studying.

Continuous Reinforcement Schedule

• Abbreviated as CRF

• Each instance of the specified behavior is reinforced.

• Particularly useful in teaching new behavior.

• Speeds up conditioning.

• Used frequently in shaping procedures.

• Produces responding that has a low resistance to extinction but a high extinction burst.

Intermittent Reinforcement Schedule

• Only some responses are reinforced.

• Particularly useful in maintaining new behavior.

• Used frequently in maintenance procedures.

• Produces responding that has a high resistance to extinction but a low extinction burst.

4 Basic Intermittent Schedules

• Fixed ratio

• Variable ratio

• Fixed interval

• Variable interval

Fixed Ratio Schedules

• Fixed Ratio: reinforcement is contingent on a fixed number of responses.

• Abbreviated FR, e.g., FR5, FR500

• Produce a high rate of responses and a short post-reinforcement pause.

• See figure 7.1

• Ratio strain: a disruption in performance due to an overwhelming response requirement.

Responses to FR Schedules

• Usually a high rate of response with a short postreinforcement pause.

• Example:

  • On an FR 25 schedule, a rat rapidly emits 25 lever presses, munches down the food pellet it receives, and then snoops around before emitting more lever presses.

• A postreinforcement pause is a short pause following the attainment of each reinforcer.

• Higher ratio requirements produce longer postreinforcement pauses.

• Example:

  • You will take a longer break after completing a long assignment than after completing a short one.

• There may be little or no pausing with an FR1 or FR2 schedule because the reinforcer is so close.

Variable Ratio Schedules

• Variable Ratio: reinforcement is contingent on a variable number of responses.

• Abbreviated VR, e.g., VR50, VR500

• Produce a high rate of responses and almost NO post-reinforcement pause.

• See figure 7.1

• Ratio strain: a disruption in performance due to an overwhelming response requirement.

Real Examples of VR Schedules

• Only some of a cheetah’s attempts at chasing down prey are successful.

• Only some acts of politeness receive acknowledgment.

• Only some songs that we download are enjoyable.

Fixed Interval Schedules

• Fixed Interval: reinforcement is contingent on the first response after a fixed period of time.

• Abbreviated FI20. Note that here the number refers to the duration of the interval and not the number of responses.

• Produce scalloped performance - timing.

• See figure 7.1

Responses to FI Schedules

• Responses consist of a postreinforcement pause followed by a gradually increasing rate of response as the interval draws to a close.

• Example:

  • A rat on an FI 30-sec schedule will emit no lever presses at the start of the 30-second interval, but the rate of responses will gradually increase as the 30 seconds end.

• Your study habits this term were probably very weak at the beginning of the semester, and they will increase as the semester draws to a close.

Variable Interval Schedules

• Variable Interval: reinforcement is contingent on the first response after a variable period of time.

• Abbreviated VI (e.g., VI 20). Note that here the number refers to the duration of the interval and not the number of responses.

• Produce a moderate, steady rate of performance with little or no post-reinforcement pause - timing.

• See figure 7.1 and table 7.1

Response Rate Schedules

• Differential Reinforcement of High Rates (DRH). Reinforcement is contingent upon emitting at least a certain number of responses in a given time.

• Example: a salesman has to make at least 15 sales per week to earn his bonus.

• Differential Reinforcement of Low Rates (DRL). A minimum amount of time must pass between responses in order for reinforcement to be delivered.

• Example: a teacher will only call on her student if there's an interval of at least 5 minutes between the times he raises his hand.

Noncontingent Schedules

• Fixed Time (FT). Reinforcement is delivered after a fixed interval of time, regardless of the organism’s behavior.

• Example:

  • On a fixed time 30-second (FT 30-sec) schedule, a pigeon receives food every 30 seconds regardless of its behavior.

  • People receive Christmas gifts each year regardless of their behavior on an FT 1-year schedule.

• Variable Time (VT). Reinforcement is delivered after a variable interval of time, regardless of the organism's behavior.

• Example:

  • A pigeon receives food after an average interval of 30 seconds (VT 30-sec schedule).

Superstitious Behavior

• Skinner: Superstition in the Pigeon experiments (1957).

• Noncontingent reinforcement may account for some forms of superstitious behavior.

• Behaviors may be accidentally reinforced by the coincidental presentation of reinforcements.

• This is also true of athletes and gamblers.

• Unusual events that precede a fine performance may be quickly identified and then deliberately reproduced in the hopes of reproducing that performance.

• Superstitious behavior can be seen as an attempt to make an unpredictable situation more predictable.

Complex Schedules of Reinforcement

• A combination of two or more simple schedules.

• They include:

  • Conjunctive Schedules

  • Adjusting Schedules

  • Chained Schedules

  • Multiple Schedules

  • Concurrent Schedules

Complex Schedules

• Conjunctive: Requirements of two or more schedules must be met before reinforcement is delivered.

• Get paid for every item you make. Stay at work for 8 hours actually working. FR + FI

• Most real-life schedules are conjunctive.

• Adjusting: Response requirement changes as a function of the organism's behavior while responding on the preceding schedule (working for a previous reinforcer).

• Example: May start with FR5, then move up to FR 50, etc.

• Chained: Two or more simple schedules where each link has its own SD/Sr+ and the last response produces a terminal reinforcer that reinforces the entire chain.

• Green key, peck --> red key, peck --> food.

• Goal gradient effect: increase in the strength and / or efficiency of behavior as a function of the approaching reinforcement. That's why you are more likely to become distracted when you're starting your paper. Secondary reinforcement is likely needed.

• Examples: working more efficiently near pay time, taking shorter breaks when you're almost done with an essay.

Theories of Reinforcement

• Highly influential theory to this day, developed by David Premack (1965):

• Premack Principle: behaviors associated with experience with reinforcement are viewed as reinforcers, rather than stimuli.

• According to the Premack principle, behavior is reinforced by eating the food, drinking the water, riding a bike, not by food, water, or bike.

• High probability behaviors can be used as reinforcers for low probability behaviors (e.g., running the wheel --> drinking water).

Response Deprivation Hypothesis (Timberlake & Allison, 1974)

• Extension of the Premack Theory.

• Behavior can serve as a reinforcer if:

  • Access to the behavior is restricted.

  • Its frequency falls below the preferred levels of occurrence.

• Example:

  • A rat typically runs for 1 hour a day whenever it has free access to a running wheel.

  • If the rat is then allowed free access to the wheel for only 15 minutes per day, it will be unable to reach this preferred level.

  • The rat will be in a state of deprivation with regard to running.

  • The rat will now be willing to work to obtain additional time on the wheel.