Transcript Slide 1
MEN ACT UPON THE WORLD, AND CHANGE IT, AND ARE CHANGED IN TURN BY THE CONSEQUENCES OF THEIR ACTION. B. F. Skinner, Verbal Behavior, 1957, p. 1 SHAPING CONTINGENCIES P (SR | Ro) versus P (SR | ~Ro) SR: reinforcing consequence Ro: selected operant class Any current Ro changes toward a target operant class (Ro target) with differential consequences—i.e., selection. When the environment is held constant, we have a twoterm contingency. The process is a dynamic interplay between selected aspects of current behavior and the reinforcing consequence to yield novel behavior. Operant Conditioning Operant Conditioning Operant Conditioning Operant Conditioning Three-term Contingency SD SD: discriminative stimulus SR Ro Ro: operant class SR: reinforcer Newton’s Second Law of Motion F m dv dt F: force m: mass dv/dt: acceleration Operant Conditioning PATTERNS OF BEHAVIOR • “The outstanding characteristic of operant behavior is that it can be differentiated in form and in temporal patterning by consequent events.” • Morse, 1966 PATTERNS OF BEHAVIOR • Behavior is very, very complex---but: • Behavior is not chaotic or without causes. • This means there can be a science of behavior. • There are orderly patterns to behavior. • These patterns are induced, in part, by contingencies. CUMULATIVE STUDY TIME FOR TEST T Operant Conditioning W Th F S Su M T Operant Conditioning Fixed-Interval (FI)1-min. SIGNIFICANCE OF SCHEDULES A. CONCEPT ESSENTIAL TO BEHAVIOR ANALYSIS B. DEFINITION: Arrangements for initiating and terminating stimuli in time and in relation to responses. C. Most consistent, reliable and powerful method for the generation and analysis of patterns of behavior. “Galilean” flavor of theory and investigation. D. The operation of schedules have enormous generality—species, response class, and maintaining events. E. The richest source of understanding the concepts of response units, stimulus control, reinforcement, and punishment, as well as for the generation of quantitative models of behavior. F. Concepts of motivation directly tied and certainly enriched by schedule effects. G. Schedule performances serve as dependent variables for the analysis of independent variables such as drugs, toxicants, and other environmental actions— not merely as baselines, but as factors manifesting drug effects themselves. SCHEDULE CLASSIFICATION • I. Response independent (FT t and VT t) • II. Response dependent a) responses only (e.g. FR n and VR n) b) responses and time (e.g., FI t and VI t) c) differentiation (e.g., shaping, IRT > t, DRO t). CONTROLLING VARIABLES • I. Direct or Intrinsic (e.g., n in ratio schedules, t in interval schedules). • II. Indirect ( time in ratio schedules, response number in interval schedules, IRTs in both). • III. Stereotypic versus Dynamic Effects. Fixed-Interval (FI)1-min. Operant Conditioning Operant Conditioning Operant Conditioning Operant Conditioning Operant Conditioning Operant Conditioning O-rules, functional relations B = f (r) r: B: feedback output E-rules, feedback functions r = g (B) Figure 1. The behavior-environment feedback system Operant Conditioning MOLAR FEEDBACK FUNCTIONS: WHAT IS THE RELATION BETWEEN RESPONSE RATE UNDER SOME CONTINGENCY AND REINFORCEMENT FREQUENCY? “MOLAR” MEANS SOMETHING LIKE “IN THE LONG RUN”, BUT WITHOUT BEING VERY SPECIFIC OF WHAT “LONG-RUN” MEANS. Operant Conditioning WHAT IS THE RELATIONSHIP BETWEEN O-RULES AND E-RULES? CAN WE PREDICT O-RULES FROM E-RULES? IN GENERAL, THE RELATIONS ARE NOT SIMPLE. Ratio-Like Feedback Functions r mg ( B); m 1/ n r kB p r aB bB c 2 Baum’s (1992) Proposed VI t Feedback Function B a (1 a)e r cB Bt a (1 a)e 1 cB OTHER POSSIBILITIES r A sin (kB) 2 dB r g dt Tav K ( IRTav)(1 IRTav) IN VERY FEW CASES, SPECIFIC ANALYTIC FEEDBACK FUNTIONS FOR THE “COMMON” SCHEDULES HAVE NOT BEEN SPECIFIED. IN FACT, THIS TASK CAN BE VERY CHALLENGING. IN SOME FEW CASES WE CAN GUESS WHAT THE GENERAL FORM OF THE FUNCTION MIGHT BE. EXAMPLE: THE VARIABLE-INTERVAL SCHEDULE. Operant Conditioning Operant Conditioning Feedback Functions Fixed or Random Ratio ( FR n or RR n) r = mB r = reinforcer rate, B = response rate, m = reinforcers, response = 1/n Variable or Random Interval ( VI t or RI t) r = B [ a + (1-a) exp (-cB)] / (tB [a + (1-a) exp (-cB)] + 1) Baum, 1992 Operant Conditioning PROBLEM: HOW DOES BEHAVIOR COME UNDER CONTROL OF A MOLAR FEEDBACK FUNCTION? THIS QUESTION RAISES THE ISSUE OF MOLAR vs. MOLECULAR ANALYSIS. MOLAR CONTROL MUST EMERGE FROM SHAPING AT THE MOLECULAR LEVEL. HOW? HOW DO VARIABLE-RATIOS (VR n) AND VARIABLEINTERVALS (VI t) COMPARE? “Variable-ratios control a higher rate than variable-intervals.” WHY IS THIS STATEMENT, AT BEST, IMPRECISE AND, AT WORST, OUTRIGHT WRONG? How can we make the statement precise? What is an essential control condition? ONE POSSIBLE WAY IS THROUGH DIFFERENTIAL REINFORCEMENT OF INTER-RESPONSE TIMES (IRTs). FOR EXAMPLE, RATIO SCHEDULES FAVOR SHORT IRTs. WHY? INTERVAL SCHEDULES FAVOR LONGER IRTs. WHY? THE TWO CONTINGENCIES MUST PROVIDE EQUAL REINFORCEMENT FREQUENCY! THUS THE PROPER STATEMENT IS: “GIVEN EQUAL OBTAINED REINFORCEMENT FREQUENCY, VARIABLE-RATIO SCHEDULES WILL CONTROL A HIGHER RATE OF RESPONDING THAN VARIABLE-INTERVAL SCHEDULES.” BUT HOW DO WE ARRANGE THIS? QUESTION IF INSTEAD OF COMPARING THE TWO SCHEDULES ON THE BASIS OF EQUAL REINFORCEMENT FREQUENCY, WE WANTED TO COMPARE ON THE BASIS OF EQUAL RESPONSE REQUIREMENTS (i.e., the number of responses/reinforcer), HOW WOULD WE DO THAT?