Flashcards
Avoidance learning and stimulus control
Flashcards do conjunto (15)
- 1Negative reinforcementremoval or escape from aversive stimuli
e.g. take panadol
ALSO encompasses avoidance: response that postpones or prevents aversive event e.g. paying tax to avoid fine - 2Signalled avoidance - Solomon and Wynne problem?Experimenter provides signal for imminent shock, gives rat chance to jump barrier before shock is given
Initially latency >10sec, but avoid shock after 8 trials
Problem: how can nothing (i.e. never getting shock) reinforce behaviour - 3two factor theorypair tone and shock > conditioned fear to tone
when rat jumps hurdle and terminates tone fear is reduced
fear is aversive, termination of this state reinforces jumping
fear reduction is form of negative reinforcement
1. CC of fear to tone
2. reinforcement of avoidance response by termination of tone - 4Rescorla and LoLordo evidence supporting two factor theoryShock occured at fixed time interval every 10sec, if jumped had 30sec grace period
discriminative fear conditioning trials CS+ tone/shock, CS- no tone/ shock
Sidman avoidance training resumed, those in CS+ jump rate doubled, CS- fell to almost zero - 5Problems with two factor theory free operant avoidance, fearlessness, extinction, response problemdoes not explain free operant avoidance - i.e. avoidance without warning
Fearlessness: after response is well learnt subjects respond without fear
extinction of avoidance behaviour: each trial where shock is avoided is CC trial, fear should gradually weaken on extinction but doesn't
Response problem: can't train rats to bar press to avoid shock - 6Bolles fable to explain response problemspecies specific defence reactions
fleeing, freezing, fighting
1. response depends on nature of aversive stimulus
2. response opportunities provided by environment
pressing lever to avoid shock is beyond animals innate responses - 7Persistence of avoidance in absence of fear - cognitive reasoningavoidance based on expectation of responses
1. warning signal: shock > animal jumps
2. warning signal : jump > no shock - new expectation, if jump shock doesn't occur
3. next signal animal remembers both expectations and performs behaviour that will give desired outcome i.e. no shock
fear is CC and plays role in directing initial reaction, but then behaviour is based on expectation - 8difficulty of extinguishing avoidance behaviouranimal learns to avoid shock, hence it cannot be extinguished as they never learn what would happen if they didn't respond
- 9Stimulus control pigeon and colour keykey illuminated with 580nm
reinforced on VI schedule with grain
randomly presented without reinforcement and changed nm
vigorous at training signal
substantial pecks at 570 and 590
responding fell off sharply when test lengths diverged from these behaviours - 10Stimulus generalisationresponse to training stimuli spread to other stimuli
used to measure stimulus control - how sensitive organism is to variations of environment - 11Stimulus generalisation gradientmeasure of degree of stimulus control
steep = good control
flat = poor control - 12Selective attentiononly subset of stimuli present come to control responding
red+triangle, green+circle
present separately one bird responded to red the other to the triangle - 13Discriminationgreater control, narrower responding
sometimes want to do this - e.g. discriminate between red and green lights - 14Discrimination training2000Hz: lever press>food
1200Hz: lever press>no food
repeated exposure would learn to lever press only at 2000 - 15Application of stimulus control - sleep insomnia1. go to bed when sleepy
2. use bed only for sleeping and sex
3. cannot fall asleep within 10-20mins get out and come back later
4. repeat above
5. use alarm and get up each day regardless of how you've slept
6. do not nap
Goal: make laying in bed cue for sleeping
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- Psy236 FlashCards sobre Avoidance learning and stimulus control , criado por steph.goodman94 em 10-11-2014.
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- steph.goodman94
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