PSYC 356 Lecture Notes - Lecture 10: Response Bias, Happy Hour, Controllability
1
PSYC 356 Chapter 6: Schedules of Reinforcement and Choice Behavior
Instrumental Conditioning Foundations
Contingency vs Contiguity: Controllability
Controllability: influences learning causality (ie. contingency)
The Shuttle Box: Dogs hate shocks (who wouldn’t?)
●Negative reinforcement involved
●Learning contingency
●What happens if our subject is unable to see contingency?
●***Triadic Design***
Triadic Design:
Group
Phase 1: Exposure
Phase 2: Escape/ Avoidance Test
E
Escapable Shock
Rapid avoidance learning
Y
Inescapable shock
Slow avoidance learning
R
Restricted to box
Rapid avoidance learning
Subjects in Group Y feel “helpless” because there is no response- reinforcer contingency
↳No learning
Attention deficit theory
●Inescapable shock→ difficulty attributing a choice to reinforcer
What if
we MARK the response?
●Maier et al. 1987
○Y-M Group: marking the escape response reversed “helplessness”
○Marking correct escape response also provides contingency
●I thought marking does not necessarily mean they are getting reinforced?
○Just showing option, that you made a choice
○This isn’t an example of perfect marking
Controllability: Learned Helplessness
Learned Helplessness Hypothesis
●Perceived lack of control over environment → Depression
2
○Reduced motivation
○Difficulty identifying effective behaviors
●What procedure(s) could overcome learned helplessness in humans?
Schedules of Reinforcement:
●We’ve focused on perfect contingency, but this is rare
●Schedule of reinforcement: a rule determining whether a response will be followed by a
reinforcer
●Schedules influence how a response is learned and maintained:
○Examples?
Simple Schedules: a single factor determines the occurrence of the reinforcer
●Ratio Schedules: reinforcement depends upon the number of responses performed
○Continuous Reinforcement: every time the response is occurs, so does the reinforcer
○Partial Reinforcement: response is reinforced only some of the time
Fixed Ratio (FR): a fixed ratio between the number of responses necessary to produce the reinforcer
Schedule Responses Reinforcement
●Ex 1: FR10: 10 lever presses 1 food pellet
●Ex 2: FR6: 6 passcode #’s Phone opens
●Continuous reinforcement (FR1) — steady moderate responding
●Partial reinforcement (FR50) — produces vigorous responding
●Characteristics
○Post- reinforcement pause:
■↓ responding just after reinforcer
○Ration run: a high steady rate of responding that completes the ratio
○Ratio strain: rapid ↑ in FR requirement results in long pre-reinforcement pauses
Variable Ratio (VR)
●In a FR schedule, the subject “knows” how many responses are needed
●BUT, reinforcement is often unpredictable
○Ex 1 Slot Machines
○Ex 2 Commission
●Variable Ratio: a different number of response are required for reinforcement
○Ex. VR10: Criteria order: 9, 6, 11, 14
Average # needed = 10 responses
3
Simple Schedules: Variable Ratio vs Fixed Ratio
●Characteristics of VR schedule vs. FR schedules:
○Fewer post-reinforcement pauses
○Fewer ratio runs
○More resistance to ratio strain
○WHY? 12:25
Simple Schedules: Interval Schedules
●Interval schedules: responses are reinforced if they occur after a certain amount of time
○Fixed interval schedule (FI): the time between reinforcers is constant
■ie. washing clothes in a washing machine
○Variable interval schedule (VI): the time between reinforcers is variable
■ie. waiting for the dealership to fix your car
■Something important said at 12:30
Fixed interval (FI)
●Characteristics
○Responses cluster around reinforcer delivery (FI scallop)
■Sill freshman (not you), might wait to study until just before the exam
○Depend upon the ability to perceive time
■Ferster and Skinner (1957):
Visual stimuli increased “scalloping”
Variable interval (VI)
●Characteristics
○VI schedules support steady, stable rates
○Once time has past, the response will be reinforced (2 min or 90 min)
○Limited hold: a restriction on the length of a time a reinforcer will be available
■Ex. seeing the sunset on the beach
■Ex. a lion waiting for an impala
Ratio vs Interval Schedules
●Interresponse Time (IRT): interval between responses
○If short IRT’s are reinforced, ↑ responding
○If long IRT’s are reinforced, ↓ responding
●Ratio schedules depend upon response accumulation, the faster to criterion the more likely
reinforcement
Document Summary
Psyc 3 chapter : schedules of reinforcement and choice behavior. The shuttle box: dogs hate shocks (who wouldn"t?) Subjects in group y feel (cid:483)helpless(cid:484) because there is no response- reinforcer contingency. Inescapable shock(cid:516) difficulty attributing a choice to reinforcer. Y-m group : marking the escape response reversed (cid:483)helplessness(cid:484) Marking correct escape response also provides contingency. Just showing option, that you made a choice. This isn"t an example of perfect marking. Perceived lack of control over environment (cid:516) depression. We"ve focused on perfect contingency, but this is rare. Schedule of reinforcement : a rule determining whether a response will be followed by a. Schedules influence how a response is learned and maintained: reinforcer. Simple schedules: a single factor determines the occurrence of the reinforcer. Ratio schedules : reinforcement depends upon the number of responses performed. Continuous reinforcement : every time the response is occurs, so does the reinforcer. Partial reinforcement : response is reinforced only some of the time.
