Aversive Control: Avoidance and Punishment

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 • 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 • 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 tone Suppression ratio 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) • 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