1 Quiz Question: In what way are fixed-ratio (FR) and variable-ratio (VR) reinforcement schedules: (a) similar? (b) different?

2 Quiz Answer: similar: based on number of responses different: fixed: number fixed different: fixed: number fixed variable: number varies

3 Have I witnessed a hurricane? Answer: Heck yeah! X

4 Reinforcement Definition ã A stimulus change ã contingent on some aspect of a response that ã increases the future probability of the response

5 Distinguishing Characteristics of Reinforcement Type ã Social ã Edible ã Tangible Reinforcement history ã Primary (unconditioned) reinforcer: Reinforcer whose effects are not dependent upon prior learning ã Secondary (conditioned) reinforcer: Reinforcer whose effects are acquired through pairing with other reinforcers

6 Determinants of Reinforcement Effects 1. Reinforcer Parameters ã Immediacy ã Contingency ã Magnitude ã Quality

7 Determinants of Reinforcement Effects 2. The Establishing Operation (EO) ã Antecedent event that:  Alters the effectiveness of a given reinforcer, and  Increases the likelihood of behavior that has produced that form of reinforcement in the past ã Types of EOs  Deprivation: Typical EO for behavior maintained by Sr+  Aversive stimulation: Typical EO for behavior maintained by Sr-

8 Schedules of Reinforcement Schedules of reinforcement determine the frequency and distribution of behavior in time Definition: A formula (or rule) describing the probability that a given R will produce reinforcement; or, a formula describing the proportion of Rs that will be reinforced Schedules are based on a continuum of probability values ContingencyScheduleProbability of Sr Every R  Sr Continuous Sr (CRF) p =1.0 No Rs  Sr Extinction (EXT)p = 0 Some Rs  Sr Intermittent Sr (INT)0 < p < 1.0

9 Advantages of Intermittent Reinforcement ã Prevents satiation: INT Sr maintains state of deprivation (EO) ã Resistance to EXT?: INT Sr is less predictable than CRF; therefore; change to EXT more difficult to discriminate ã Can produce high rates of R (more Rs required for Sr) ã Naturalistic: Most schedules in natural environment are INT ã Cost effective: Easier for agent to administer

10 Basic Schedule Parameters Response requirement: ã Ratio: Sr based on number of Rs ã Interval: Sr based on time elapsed since last reinforced R Regularity: ã Fixed: Requirement constant between Sr deliveries ã Variable: Requirement changes from one Sr delivery to another

11 Basic Schedules of Reinforcement RatioInterval (# of Rs)(Time since last reinforced R) Fixed(Requirement for Sr constant) Variable(Requirement for Sr changes) Fixed Ratio (FR) (Sr delivered following fixed # of Rs) Fixed Interval (FI) (Sr delivered for 1st R after fixed amt of time since last reinforced R) Variable Ratio (VR) (Sr delivered following # of Rs that varies around an average value) Variable Interval (VI) (Sr delivered for 1st R after variable amt of time since last reinforced R)

12 Schedule Effects on Behavior RatioInterval (High R rate)(Moderate R rate) Fixed(Irregular R rate) Variable (Stable R rate) Fixed Ratio (FR) High, irregular rate (PRP, break & run) Fixed Interval (FI) Moderate irregular rate (FI scallop) Variable Ratio (VR) High stable rate Variable Interval (VI) Moderate stable rate Real life examples?

13 Response Patterns Generated by Basic Schedules Sr+ PRP Break & Run

14 Response Patterns Generated by Basic Schedules

15 Response Patterns Generated by Basic Schedules Sr+ FI Scallop

16 Response Patterns Generated by Basic Schedules

17 Guess the Schedule!

18 How hard is graduate school? Answer: pretty darn hard Answer: but it also depends

19 Quiz #2 Question:

20 Activity: 9/12 Preference Assessment Methods: to identify potential reinforcers Indirect: checklists (RAISD, RAQ) Descriptive: Premack Experimental: Paired-stimulus Preference Assessment (Fisher et al. 1992) Reinforcer Assessment: to validate reinforcement effects Practice various schedules