1. Aversive Control: Avoidance and Punishment

2. Avoidance/Escape
Escape: getting away from an aversive stimulus in progress
Avoidance: preventing the delivery of an aversive stimulus
Negative contingency between response and aversive stimulus
Increase in operant responding

3. Brogden et al. (1938) Guinea pigs
CS = tone, US = shock, UR = pain, CR = running
Classical conditioning group
CS followed by US
Avoidance group
CS -- CR --> no US
CS -- no CR --> US

4. Discriminative Avoidance
Stimulus signals onset of aversive US
Avoidance
Escape CS CS US US R R

5. Shuttle Box
Standard experimental paradigm

6. Escape In presence of aversive stimulus Make response
Aversive terminated
Negative reinforcement

7. Avoidance “Paradox” Make response before aversive delivered
Behaviour clearly increases, so reinforcer
But what is taken away (or delivered)?
Mowrer & Lamoreaux (1942)
“…not getting something can hardly, in and of itself, qualify as rewarding.”

8. Two-Process Theory Two mechanisms: classical and instrumental
1. Classical conditioning process activated by CS when avoidance not made; CR of fear produced
2. Negative reinforcement: successful avoidance removes fear caused by CS
Classical and instrumental conditioning processes are independent
Avoidance = escape from fear, not prevention of shock

9. Acquired Drive Experiment
Phase 1: condition fear to CS through classical conditioning procedure
Phase 2: let subject make operant response to terminate CS
No shock
Drive to avoid learned through classical conditioning

10. Brown and Jacobs (1949) Rats in shuttle box
Experimental and control groups
Phase 1: light/tone CS --> shock
Phase 2: CS --> no shock; turn CS off by crossing barrier
Measure: time to change sides
Supports two-process theory
Termination of fear CS drives operant response

11. Rescorla & LoLordo (1965) Dog in shuttlebox Pair tone with shock
No signal
Response gives “safe time”
Pair tone with shock
Tone increases rate of response
CS+ can amplify avoidance
CS- can reduce avoidance

12. Problems for Theory Fear a necessary component
Fear reduction with experience

13. Kamin, Brimer & Black (1963) Rats
Lever press in operant chamber for food
Auditory CS+ for shock; avoidance in shuttle box until: 1, 3, 9, 27 avoidances in a row
CS+ in operant chamber; check for suppression of lever press

14. Alternation of Behaviour (Yo-yo)
Every successful avoidance puts CS on extinction
With extinction, fear drops, so motivation to avoid decreases
Resulting in more shocks, strengthening CR again and increasing avoidance response
But… we don’t really see this

15. Persistence of Avoidance
Sometimes a problem
Phobias
Need to extinguish avoidance
Flooding, response prevention

16. Sidman Free-Operant Can avoidance be learned without warning CS?
Shocks at random intervals
Response gives safe time
Extensive training, but rats learn avoidance (errors, high variability across subjects)

17. Hernstein & Hineline (1966)
Rapid and slow shock rate schedules
Response switches from rapid to slow
Shift back to rapid random so no time signal
Response produces shock reduction

18. Reduction of Shock Frequency
Molar account
Response reduces in amount of shocks over long run
Negative reinforcement
Overall shocks taken away, behaviour increases

19. Safety Signals Molecular account Positive reinforcement
Context cues associated with “safety”
Either SD or CS-
Making response gives safety
Giving explicit stimuli makes avoidance learning easier

20. SSDRs Species-specific defense reactions Innate responses; evolved
SSDRs predominate in initial stages of avoidance
Hierarchy
If first SSDR works, keep it
If not, try next, etc.
Aversive outcome (punishment) is the selector of appropriate avoidance response

21. SSDRs Fight, flight, freeze
Also thigmotaxis, defensive burying, light avoidance, etc.
Environmental content influences selected SSDR
E.g., freezing not useful if predator right in front of you…
Some responses easier to learn than others
E.g., rats: wheel run --> avoid shock (easy)
E.g., rats: rear --> avoid shock (hard)

22. Predatory Imminence
Different innate defensive behaviours at different danger levels

23. Differences from SSDR 1. Behaviours in anticipation, not response
2. Predatory imminence, not environmental cues leads to response
3. Not selected via punishment

24. Punishment Positive punishment Negative punishment Time out
Delivery of stimulus --> reduction in behaviour
Negative punishment
Removal of stimulus --> reduction in behaviour
Time out
Overcorrection

25. Introduction of Punisher
Effective use of punishment
Tolerance
Start with high(er) intensity
Can then reduce and behaviour will remain suppressed

26. Response-Contingent vs. Response-Independent
Does your response cause the aversive outcome?
More behavioural suppression if aversive stimulus produced by operant response
Phase 1: train on VI-60 sec
light
Phase 2: tone light
FR-3 response-independent
punishment
punishment Yoked
Suppression ratio
tone
Trials

27. Delay Interval between response and delivery of aversive
Longer the delay, less suppression of behaviour

28. Punishment Schedule Continuous or intermittent schedules Azrin (1963)
Different FR punishment schedules; responding maintained with VI reinforcement
no punishment
FR 1000
FR 500
Cumulative responses
FR 100
FR 5
Time

29. Positive Reinforcement Schedules and Punishment
Without some positive reinforcement, behaviour generally stops quickly
As in previous study, responding maintained with appetitive outcome on VI schedule
Interval
Overall decrease
VI: suppressed but stable
FI: scalloping
Ratio
Increases post-reinforcement pauses

30. Alternative Sources of Reinforcement
Options
No alternatives but punished behaviour
Alternative behaviours (e.g., differential reinforcement schedules; DRA, DRI, etc.)
Availability of reinforceable alternatives increases suppression of punished response
no punishment
Punishment, no alternative response available
Cumulative responses
Punishment, alternative response available
Time

31. SD for Punishment Suppression limited to presence of SD
E.g., garden owl
E.g., cardboard “cops” and “kids”

32. Punishment as SD for Availability of Pos. Reinf.
Sometimes punishment seeking behaviour
Punisher becomes S+ for positive reinforcement
E.g., masochism, children seeking attention

33. CER Theory of Punishment
Estes (1944)
Conditioned suppression
E.g., freeze prevents lever press
CER incompatible with making response
Punishment suppresses behaviour through same mechanism
In real world, no explicit CS
Stimuli immediately before punished response serve this function
Estes (1969): incompatible motivational state

34. Avoidance Theory of Punishment
Tied to two-process theory
Engage in incompatible behaivour
Prevents making punished behaviour
Strengthening of competing avoidance response
Not weakening of punished response
Same theoretical problems of avoidance

35. Negative Law of Effect Thorndike (1911) Similar to Premack Principle
Positive reinforcement and punishment are symmetrical opposites
Similar to Premack Principle
Low probability behaviours reduce high probability behaviours
Forced to engage in low-valued behaviour after doing high probability behaviour