Chapter 8

Four Contingencies

• Positive reinforcement
• Negative reinforcement
• Positive punishment
• Negative punishment

Reinforcers and Punishers

• Reinforcer: increases a behaviour
• Punisher: decreases a behaviour

Positive and Negative

• Positive: presents some stimulus
• Negative: removes some stimulus

Contingencies

Avoidance/Escape

• Escape
• Get away from aversive stimulus that is in progress
• Avoidance
• Get away from aversive stimulus before it begins

Shuttle Box

• Solomon & Wynne (1953)
• Dogs
• Chamber with barrier; Shock
• Light off as signal

Avoidance Paradox

• How can non-occurrence of an event serve as a reinforcer?
• Problem for avoidance
• Not a problem for escape

Two-Factor Theory

• Classical and operant conditioning
• Shock = US
• Fear/pain/jump/twitch/squeal = UR
• Darkness = CS
• Fear of dark = CR
• Fear: heart rate, breathing, stomach cramps, etc.

Two-Factor Theory

• Negative reinforcement
• Removal of fear (CR)
• Avoidance/Escape of CS, not shock

Support for Two-Factor Theory

• Rescorla & LoLordo (1965)
• Dog in shuttlebox
• No signal
• Response gives "safe time"
• Pair tone with shock

• CS can amplify avoidance
• Conditioned inhibition can reduce avoidance

Problems with Two-Factor Theory

• Avoidance without observable fear
• Heart rate

• Fear diminishes with avoidance learning

Measuring Fear

• Kamin, Brimer, and Black (1963)
• Lever press ---> food
• Auditory CS ---> avoidance in shuttle box until: 1, 3, 9, 27 avoidances in a row
• CS in Skinner box; check for suppression of lever press

Results

• Fear decreases during extended avoidance training
• But, avoidance still strong
• Even low fear is enough?

Extinction in Avoidance Behaviour

• Odd prediction from two-factor theory
• "Yo-yo" effect
• Avoidance should toggle
• But! Avoidance is extremely persistent

One-Factor Theory

• Classical conditioning component unnecessary
• Avoidance, not fear reduction, is reinforcer

Sidman Avoidance Task

• Free-operant avoidance
• Can avoidance be learned if no warning CS?
• Shock at random intervals
• Response gives safe time
• Extensive training --> learn avoidance
• But, usually never perfect
• High variability across subjects
• Two-process theory suggests:
• Time becomes a CS (time elicits fear)

Herrnstein & Hineline (1966)

• Rapid and slow shock rate schedules
• Lever press switches schedules
• Shocks presented randomly, no signal
• Responses give shock reduction
• Reduction in shock is reinforcer

One-Factor Theory of Avoidance Extinction

• Discrimination between contingencies
• How does animal know extinction is in effect?
• One-process theory
• e.g., higher barrier/harness is new stimulus
• Two-process theory
• Extinction of CR (fear)

Other Explanations of Escape/Avoidance

Biological Constraints in Avoidance Learning

• Species-Specific Defense Reactions (SSDRs)
• Bolles (1970)
• Freeze, flee, fight
• Situation and species dependent
• Some responses easier to learn than others

Predatory Imminence

• Different SSDRs at different danger levels
• Differences from SSDR

 

 

 

Positive Reinforcement via Conditioned Inhibition

• Avoidance --> distinctive feedback stimuli
• Safety signals --> conditioned inhibitory signals

• Prediction: give explicit stimuli, avoidance easier

• Not explicit about source of fear: context cues, environmental stimuli, etc
• Positive reinforcement not incompatible with negative reinforcement of 2-process theory
• Both --> reduction of fear
• Different mechanisms
• CS- --> inhibits fear
• CS termination passive disruption of fear

Flooding

• Force animal not to avoid

 

• Extinction schedule
• Flooded with exposure to extinction

Explanations of Flooding

• Cognitive theory

• One-factor theory

• Two-factor theory

Learned Helplessness

• Behaviour has no effect on situation
• Generalizes
• Human condition

Situation

• Give unavoidable/inescapable shocks
• Shuttle box
• Usually, will not jump barrier
• Expectation that behaviour has no effect

Maier & Seligman (1976)

• Motivational impairment
• Cognitive impairment
• Emotional impairment
• Is there hope?

Learned Helplessness in Humans

• Depression
• Situations beyond your control
• Three dimensions
• Situation: specific or global
• Attribute: internal or external
• Time: short-term or long-term

Therapy

• Can not fail
• "Confidence building"
• Immunization
• Phase 1: Situation in which subject can escape
• Phase 2: Inescapable shock
• Test

Application to Humans

• Confidence building
• Tasks that can be successfully completed

• Learned helplessness less likely to develop
• Premack

Factors in Punishment

• Opposite of reinforcement (decreases behaviour)
• Manner of introduction (intensity)
• Immediacy of punishment
• Schedules of punishment
• Motivation to respond
• Availability of alternative behaviours

Disadvantages of Using Punishment

• Fear and anger
• General suppression of all behaviour
• Continual monitoring
• Circumvention of punishment
• Aggression
• Reluctance to administer

Negative Punishment

• Removal of pleasant stimulus
• Time-out
• Popular in human behaviour modification

Other Techniques for Behavioural Deceleration

• Overcorrection
• Repetitions of alternate, desired behaviour

 

 

• Technically, punishment
• Stimulus satiation