Transcript Aversive Control

Aversive Control
• Negative Reinforcement
• Avoidance Learning
• Escape Learning
Negative Reinforcement
Removes/Prevents
S:
SAversive e.g. shock
R
e.g. operant
chamber
e.g. bar press
Strengthens
Negative Contingency
p(SAversive/R) < p(SAversive/noR)
Note: if R removes SAversive = Escape
if R prevents SAversive = Avoidance
Discriminated or Signalled Avoidance
A warning stimulus signals a forthcoming SAversive
If the required response is made during the warning
stimulus, before the SAversive occurs, the subject avoids
the shock.
If a response is not made during the warning stimulus,
the SAversive occurs, and terminates when the required
response is made
e.g., one-way avoidance
two-way avoidance
The Two-Process Theory of Avoidance
Explains avoidance learning in terms of two
necessary processes:
1. The subject learns to associate the warning
stimulus with the SAversive
2. The subject can then be negatively reinforced
during the warning stimulus
Thus the two-process theory reduces avoidance learning
to escape learning; the organism learns to escape from
the CS and the fear that it elicits.
The Two-Process Theory of Avoidance
Acquired-drive experiments support the Two-Process
Theory of Avoidance since animals do learn to escape
from the CS
Problems for the Two-Process Theory of
Avoidance
1. Level of fear is not always positively correlated
with avoidance
2. Avoidance behavior should cycle at asymptote, but it
typically does not.
3. Avoidance behavior should not be learned if the
response does not terminate the CS, but it is.
4. Animals can learn Free-Operant (or Sidman)
avoidance
Alternative Theoretical Accounts of Avoidance
Behavior
1. Positive reinforcement through Conditioned Inhibition
of fear
 Conditioned Safety Signals
 performance of the avoidance response results in
distinctive feedback stimuli (i.e., spatial cues, tactile
cues, etc…)
 the avoidance response produces a period of safety
allowing the feedback cues to become signals for the
absence of shock (i.e., safety signals)
 since a shock-free period is desirable, a conditioned
inhibitory stimulus for shock could serve as a positive
reinforcer
Alternative Theoretical Accounts of Avoidance
Behavior
2. Reinforcement of avoidance through reduction of shock
frequency
 with Two-Process theory, reduction in shock
frequency was by-product of avoidance responses
 reduction in shock frequency is important
 rats will press lever to reduce frequency of shocks
from 6/min to 3/min
Alternative Theoretical Accounts of Avoidance
Behavior
3. Avoidance and Species-Specific Defense Reactions
(SSDRs)
 more concerned with the actual response and what
determines the animal’s response early in training
 aversive stimuli elicit strong innate responses
(i.e., freezing, flight, fighting, seeking out dark areas)
 species typical responses are readily learned as
avoidance responses (e.g., Jump out of box in two
trials versus press a lever to avoid shock 1000s of trials)
 punishment is responsible for the selection of the
avoidance response
Punishment
Produces
S:
SAversive e.g. shock
R
e.g.
operant
chamber
e.g. bar press
Weakens
Positive Contingency:
Aversive
p(S
Aversive
/R) > p(S
/noR)
Punishment
Usually a response that must be punished is maintained
by a positive reinforcer, thus experimentally SAversive is
usually made contingent on a response that has been or
is being positively reinforced.
Both Skinner and Thorndike claimed punishment
was not very effective in suppressing behavior
Skinner’s Experiment on Punishment
Phase 1:
Rats were reinforced with food on a VI schedule
Phase 2:
Extinction for 120 minutes on two successive days
During only the first 10 min of extinction on day 1;
one group of rats was punished for each bar press
(paw slapped); the other, control, group was not
punished.
Results of Skinner’s Experiment on Punishment
Punishment suppressed responding while it was being
administered, but when punishment stopped, the
punished rats ended up making as many responses
overall in extinction as the unpunished controls.
Skinner concluded that punishment was not an effective way
to control behavior.
Consideration of administration of punishing
stimulus: Punishment effective if punishment:
 is intense/prolonged from start
 is response contingent rather than response
independent (fig 10.13)
 occurs immediately after response rather
than delayed
 is on a continuous rather than partial
reinforcement schedule (fig 10.14)
Consideration of response to be punished:
Punishment effective if:
 punished response is not being reinforced;
or motivation for reinforcer is reduced
 there is an alternative response to the punished
response to acquire reinforcer (fig 10.15)
 the punished response is not a species-specific
defence reaction
Consideration of situation in which punishment
is to be administered; punishment effective if:
 subject cannot discriminate when punishment
will be administered and when not
 punishment does not signal SAppetitive
Problems that may arise with the use of
punishment to eliminate behavior:
 undesirable CERs to the situation and/or person
associated with punishment
 general suppression of responding
 difficulties in applying punishment systematically
so that it is effective (e.g., discriminative cues;
punishing every instance of the behavior
 imitation of the aggressive behavior involved in
punishment
 escape/avoidance or aggressive responses
in punishing situation
Practice Exams
Midterm
1. According to the Rescorla-Wagner model, learning will only occur
if an animal has experienced a(n)
.
A. CS
B. US
C. UR
D. CR
2. Suppose a 5-second tone is presented, then a 5-second gap, then
food. Now 60 seconds pass, and the tone-gap-food sequence is again
presented. In this example, the CS-US intervalis
seconds, and the
intertrial interval is
seconds.
A. 10; 60
B. 10; 70
C. 5; 60
D. 5; 70
3. You have discovered a new species of creatures, the zorks. They
eat birds and identify those birds that are edible by their call. Zorks are
bothered by stinging insects who mark their territory with a sour fluid:
The zorks use this taste to avoid the insects’ territory. Suppose you
perform the “bright, noisy, and tasty” water study, in which
light/tone/saccharin CSs are paired with USs of shock or poison.
If you assume the nonequivalence of associability, then the zorks who
got
USs should stop drinking only during a
cue.
A. Shock; light/tone
B. Shock; saccharin
C. Poison; saccharin
D. Poison; light
4. You have established a tone as a conditioned inhibitor (a CS-),
using a shock US. Which of the following procedures would be
most likely to cause the tone to lose its inhibitory power?
A. Present the tone alone for 20 trials
B. Present the tone alone for 200 trials
C. Present 100 trials where the shock is followed by the tone
D. Present 100 trials where shocks and tones are given randomly
5. Suppose animals in Group 1 are exposed to a number of electric
shocks, while animals in Group 2 are not. Next, all animals are given
tone-shock pairings. What is the typical result?
A. Both groups acquire a CR at the same rate
B. Group 1 acquires a CR more quickly than Group 2
C. Group 1 acquires a CR more slowly than Group 2
D. Group 1 develops an inhibitory CR
6. Which of the following produces the strongest conditioning?
A. Simultaneous conditioning
B. Backward conditioning
C. Trace conditioning
D. Delayed conditioning
7. Which of the following is an example of a CR?
A. Salivating when lemon juice is put on your tongue
B. A pigeon pecking grain
C. Feeling nauseated when seeing moldy food.
D. Flinching when a tree limb falls near you.
8. Which of the following is an example of an unconditioned response?
A. You run when someone yells, “Fire!”
B. Your mouth waters when you think about chocolate cake.
C. You jump when a balloon pops behind your head.
D. Your dog wags its tail when you open a can of dog food.
9. When did Pavlov present the sound of a metronome and food
powder?
A. Whenever the dog was hungry
B. When the dog was quiet and not reacting to other stimuli
C. As soon as the dog salivated
D. Independent of the dog’s behavior
10. According to contingency theory, inhibitory conditioning occurs
to a CS only when:
A. CSs and USs never occur together.
B. Unsignaled USs are more likely than signaled USs.
C. Signaled USs are more likely than unsignaled Uss
D. The likelihood of getting a signaled US is the same as the
likelihood of getting an unsignaled US.
1 (4%). “Extinction entails the elimination of an association.”
Evaluate this quote, and provide evidence supporting your conclusions.
2 (3%). “Pavlovian conditioning is merely a way of teaching
conditioned reflexes.” Evaluate this quote.
3 (2%). Describe an experiment that supports the S-R theory of
second-order conditioning.
4 (4%). What advantage does the Pearce-Hall model have over the
Rescorla-Wagner model in explaining data from unblocking
experiments?
5 (2%). Describe two common procedures for measuring conditioned
inhibition.
Practice Exams
Final
1. Which of the following procedures results in a decrease in an
instrumental response?
A. Avoidance conditioning
B. Escape conditioning
C. Omission training
D. Reward training
2. Suppose a study is conducted with rats. In phase 1, Group T-F is
given tone-food pairings, while Group F is only presented with food.
In phase 2, a lever is inserted, and each lever press is followed by the
tone. What would convince you that the tone is a conditioned
reinforcer?
A. Either group pressed the lever in phase 2
B. Group F failed to press the lever
C. Group T-F pressed the lever in phase 2
D. Group T-F pressed the lever more than Group F
3. Punishment in operant conditioning is analogous to excitatory
aversive conditioning in Pavlovian conditioning. What, in the
punishment procedure, is analogous to the CS, in Pavlovian
conditioning?
A. The aversive stimulus
B. The operant response
C. The suppression of the response
D. The reward
4. Your friend is attempting, unsuccessfully, to teach her dog to shake
hands using an operant conditioning procedure. You are concerned with
contiguity, so you advise your friend:
A. To give the treat immediately after the dog responds
B. Not to wait too long between saying “shake” and giving the treat
C. To first reinforce any movement of the right paw
D. To swat the dog’s nose if it fails to quickly offer its paw
5. Whenever a light comes on, a rat’s lever press is followed by a food
pellet. To begin the extinction phase, the researcher should:
A. Stop turning on the light
B. Stop delivering food after lever presses
C. Remove the lever
D. Both A and B
6. The type of schedule that typically produces a pause and then an
accelerating rate of responding is the
schedule of
reinforcement.
A. Fixed interval
B. Variable interval
C. Fixed ratio
D. Variable ratio
7. You have discovered a new species, which eats mosquitos, and you
have observed a number of its behaviors in the wild, including jumping
(to catch mosquitos) and digging (before going to sleep). You are now
testing whether instrumental conditioning occurs for the species and
try each of the following:
1. Jumping is followed by presenting two mosquitos;
2. Digging is followed by presenting two mosquitos; and
3. Pressing a lever is followed by presenting two mosquitos
From most to least, what do you predict about how much each behavior
will increase with the above contingencies?
A. Jumping, lever pressing, digging
B. Lever pressing, jumping, digging
C. Digging, lever pressing, jumping
D. All behaviors should increase the same amount
8. If Jason sets the table, he does not have to wash the dishes.
Which procedure does this exemplify?
A. Avoidance conditioning
B. Escape conditioning
C. Omission training
D. Punishment
9. If an animal experiences
independent of its behavior,
it later has trouble learning a response in a(n)
situation.
A. shocks; avoidance training
B. Food; reward training
C. Neither A nor B
D. Both A and B
10. Two schedules which selectively reinforce long IRTs are:
A. VR and VI
B. VI and DRH
C. VI and DRL
D. VR and DRL
1 (3%). Explain why the term “reinforcement” is not defined in terms
of specific pleasurable stimuli such as food. Explain how you would
know for sure that a given stimulus is indeed a reinforcer.
2 (4%). Describe the conditions under which matching behavior does
and does not occur. Describe the two principal explanations for
matching.
3 (4%). In an operant conditioning experiment, associations can
develop between the discriminative stimulus and the response
(S-R association) and/or between the discriminative stimulus and the
outcome (S-O association). Describe an experiment that demonstrates
each of these associations (i.e. one experiment for each association).
4 (4%). Describe an experiment demonstrating the basic learned
helplessness effect. Does the learned helplessness learning deficit
result from lack of control over outcomes? (Be sure to support your
answer with experimental evidence).
1 (3%). In any experimental situation, it is necessary to determine if
the response you see is due to conditioning, or is a by-product of some
other variable (i.e. pseudo-conditioning). Describe three control
procedures used in Pavlovian conditioning.
2 (4%). How does the Two-factor theory explain avoidance
conditioning. Describe two problems for this theory.
3 (4%). A general process view of learning suggests that any
stimulus/response may be conditioned using Pavlovian/operant
techniques. Discuss the extent to which such a claim is justified,
providing experimental evidence to support your argument.
4 (4%). While both contiguity and contingency are important in
conditioning, it is thought that contingency is more important.
Describe one operant and one Pavlovian experiment that demonstrate
the importance of contingency.