Download 2. Reinforcement of avoidance Through Reduction of Shock

Consequences for Avoiding Bad Things
Extinction of Avoidance Behavior Through
Response-Blocking and CS-Alone Exposure
• Avoidance behavior can be very persistent
– It is difficult to extinguish avoidance behavior
• Avoidance behavior removes aversive situations
– It is successfully preventing an aversive outcome
– Situations that produce fear & expectancy of threat motivate avoidance
• A good thing if it is truck coming at you
• However, avoiding school is maladaptive
– Similar to procrastination
• aversive activities are difficult to start
Extinction of Avoidance Behavior Through
Response-Blocking and CS-Alone Exposure
• Response Blocking “Flooding”
– Extensive exposure to the CS (fear signal) and prevent avoidance of the CS
– Also called “Response Prevention with Extinction” (RPE)
– Longer exposure to the CS produces more extinction
• Schiff (1972)
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Avoidance of shock in response to a CS tone by running to the safe side
Prevent avoidance by blocking access to the safe compartment
Independent groups given different amounts of blocking time
Testing with CS presentation and barrier removed
Record number of trials to extinguish avoidance Figure 10.6
FIGURE 10.6
Trials to an extinction criterion for independent groups of animals that previously received various
durations of blocked exposure to the CS. (From “Extinction on Avoidance in Rats as a Function of
Duration and Number of Blocked Trials” by R. Schiff, N. Smith, and J. Prochaska, 1972, Journal of
Comparative and Physiological Psychology, 81, pp. 356–359.)
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
Flooding with Response Blocking
• Bravo-Rivera (2015)
– behavioral conflict study with hungry rats
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pressing a lever for food with occasional foot shock
avoid shock by jumping on a platform
but can not get any food while on the platform
RPE (flooding): Removal of the platform (no shocks delivered)
– initially increased fear-related freezing that subsequently extinguished
• returning the platform to the cage (but no shock)
– return of shock-avoidance responses, despite complete fear extinction
• Avoidance behavior is persistent and difficult to extinguish
– An important part of exposure-based treatments (flooding)
• identify and neutralize avoidance behaviors
• If children are skipping school what are they doing instead?
• To improve extinction of the fear or anxiety
Flooding with Response Blocking
• Low-Cost Avoidance Behaviors are Resistant to Fear Extinction in
Humans. Vervliet and Indekeu 2015
– Procedure using pictures presented on a computer screen
– Conditioning procedure was explained extensively
• Fear conditioning: 2 trials each
– Lamp with blue light for 9 sec followed 0.5 sec later by shock
– Lamp with yellow light for 9 sec with no shock
– Produced a higher fear rating to blue light
• Avoidance conditioning: clicking on red button prevented shock
– 8 trials with blue and eight trials with yellow
– More avoidance behavior (push red button) for blue light
– Fear rating for blue light becomes extinguished
• RPE (flooding): 8 trials of blue and 8 trials of yellow but no red button, no shock
– Return of high fear rating for blue light
– Then extinction of fear to blue light
• Avoidance test: 4 trials of blue and 4 trials of yellow with return of the red button
– More avoidance behavior to blue light
– Fear rating only back up a small amount then decreases
Nondiscriminated (Free-Operant) Avoidance
• Two process theory: warning signal motivates avoidance
• Nondiscriminated Avoidance (Sidman avoidance)
– Avoidance procedure without a warning signal
– rats given shocks according to a shock-shock (S-S) interval
– Can make a response to delay the shock according to a response-shock (R-S)
interval ; see procedure diagram Figure 10.7
• Characteristics
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extensive training periods for establishment of steady-state performance
never get good enough to avoid all shocks
large individual differences in responding
decreasing the S-S interval increases learning
increasing the R-S interval increases learning
relative values of S-S and R-S are important
R-S needs to be greater than the S-S
• With extensive conditioning they learned the temporal pattern
FIGURE 10.7
Diagram of the nondiscr iminated, or free-operant, avoidance procedure. Each occur rence of the
response initiates a period without shock, as set by the R–S interval. In the absence of a response, the
next shock occurs a fixed period after the last shock, as set by the S–S interval. Shocks are not signaled
by an exteroceptive stimulus and are usually brief and inescapable.
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
Demonstrations of Free-Operant Avoidance Learning
• Lejuez (1998)
• Exposure to carbon dioxide as the aversive stimulus with college students
– Experimental condition:
• S - S interval of 3 seconds
• pull a plunger response to avoid carbon dioxide
• R - S interval of 10 seconds
– Control condition
• had no avoidance contingency
• delivery of carbon dioxide every six minutes
– Results see Figure 10.8
• Response rates are higher during the avoidance condition than the control condition
• students 1 and 2 figured out the avoidance contingency immediately while students 3
and 4 were given a hint after the fifth session
• students 3 and 4 never clearly discriminated between avoidance and control
conditions
• student 1 has clear separation between avoidance and control condition
• once the avoidance contingency was discovered all the students did a pretty good job
of avoiding CO2 presentation
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
Free-Operant Avoidance and the Two-Process Theory
• Can Free-Operant Avoidance be explained by two-process theory?
– No explicit, external CS to elicit fear
– there is an internal cue
– Passage of time since the last shock elicits fear
• Termination of time signals reinforce responding through fear
reduction
• Concentration at end of R-S interval because temporal cues elicit
greatest fear at this point
Alternative Theoretical Accounts of Avoidance Behavior
• 1. Positive Reinforcement Through Conditioned Inhibition of Fear
or Conditioned Safety Signals
• Safety signals: ‘Feedback’ cues from avoidance responding are
spatial, tactile and proprioceptive cues associated with avoidance
• Safety signal hypothesis
– Feedback cues can produce conditioned inhibitory properties
– Feedback cues could be a source of positive reinforcement.
– Distinctive stimulus (light) presented after avoidance response will facilitates
avoidance
• Can explain free-operant avoidance
– If sensations from movements during R-S (safety period) develop conditioned
inhibitory properties.
Alternative Theoretical Accounts of Avoidance Behavior
• 2. Reinforcement of avoidance Through Reduction of Shock
Frequency
• reduction in shock frequency with avoidance responses
• Reduction in shock frequency could reinforces avoidance behavior
• Some experiments have shown that avoidance behavior will still
occur even if the shock frequency is not altered
– this can be done by delaying the shock delivery
Alternative Theoretical Accounts of Avoidance Behavior
• 3. Avoidance and Species-Specific Defense Reactions (SSDRs)
• In natural environment, avoidance learning better occur quickly
– Interested in form of response
• Various defensive behaviors (SSDRs) can occur in response to aversive
stimuli (e.g., running, freezing, defensive fighting, approaching walls, etc.)
• Which defensive behavior engaged in depends on environment
• If ‘chosen’ SSDR works, keep using it; if it does not, punishment occurs,
and another SSDR employed
• Attributes instrumental avoidance to punishment rather than
reinforcement
• Consistent with SSDR predictions, certain behaviors more conducive to
learning in avoidance experiments (i.e., running more appropriate that
standing on hind legs)
• Some issues with SSDR theory explaining experimental findings
• Punishment sometimes facilitates (rather than suppresses) ineffective
defensive responses
Predatory imminence and Defensive and
Recuperative Behaviors
• Predatory imminence continuum:
– response based on predator threat potential see Figure 10.9
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rats are reasonably safe in their borrow
but have to occasionally go out to find food
when predators are in the area level of danger increases
when predators are close enough to strike “circa strike” danger is at its peak
• Animals make behavioral adjustments to the level of danger
– for example when predator is detected rats go out less often but eat larger
meals when they go out
– Animals can also adjust their defensive behaviors within the imminence is
low rats may freeze holding still so that there are less likely to be detected
– when the predator gets close and actually makes contact the rat can leap
into the air as an “circa strike response” to escape
• Defensive behaviors are guided by unconditioned responses
– The behavior will be adjusted by encounters with predators
– Predator cue to predator encounter temporal pattern determines type of
behavioral adjustment
FIGURE 10.9
The predatory-imminence continuum (based on “Neurobiological and neuroethological perspective on
fear and anxiety” by V. Rau and M. S. Faneslow, in L. J. Kirmayer, R. Lemelson, and M. Barad [Eds.],
Understanding trauma; Integrating biological, clinical, and cultural perspectives [pp. 27–40]).
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
Expectancy Theory of Avoidance
• Experiments with non-human animals such as rats
– Unconscious associative conditioning processes
– Might have some elements of expectancy
• Experiments with humans
– form associations that do not require conscious awareness
– can also have conscious expectancy of the contingency
• Threat appraisal to determine possibility of aversive events
• which will influence conditioning and extinction rates
• Can explain persistent avoidance behavior
– Expectancy of no aversive if response is preformed
» “pushing the button when I see a blue square will prevent the shock to
my finger”
– Is this the primary cause of persistent avoidance in humans?
The Avoidance Puzzle: Concluding Comments
• Two-Process theory
• How can not getting something act as a motivator?
– conditioned inhibition reinforcement
– shock frequency-reduction reinforcement
– SSDR and Predatory imminence