Conditioned%20Inhibition

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Conditioned Inhibition

• Procedures for producing CI
• Conditional (standard) Procedure
• Negative Contingency/Explicitly Unpaired
• Differential Procedure
• Backward Conditioning
• Long-delay/Trace Conditioning

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Procedures for Measuring CI

• Directed Behavior Test
• Summation (Compound Stimulus) Test
• Retardation-of-Acquisition Test

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Chapter 4

• Classical Conditioning Mechanisms
• What makes effective conditioned and
  unconditioned stimuli?
• What determines the nature of the conditioned
  response?
• How do conditioned and unconditioned stimuli
  become associated?

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What makes effective Conditioned and
Unconditioned Stimuli?
Initial responses to the stimuli
CS does not elicit the CR initially
US elicits the target response without any
special training
Identification of CSs and USs is relative
A particular event may serve as a CS relative to
one stimulus and serve as a US relative to
another stimulus
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Saccharin a tasty solution that rats like
Saccharin can serve as the CS in a taste-aversion
experiment where illness is the US
The same saccharin could serve as the US
L
Saccharin
The animal would approach the L
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The Novelty of Conditioned and Unconditioned
Stimuli
The behavioral impact of a stimulus depends on
its novelty
Familiar stimuli do not elicit as vigorous a
response as do novel stimuli (i.e., Habituation)
Stimulus novelty is important for classical
conditioning
If the CS and/or the US are familiar,
conditioning proceeds more slowly than if they
were novel
Testing the role of stimulus novelty involves 2
phases - preexposure - conditioning
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CS-preexposure effect or Latent Inhibition
Phase 1 Preexposure
Subjects are given repeated presentations of the
CS alone
Phase 2 Conditioning
Subjects are given pairings of the CS with the US
The initial preexposure to the CS usually retards
subsequent conditioning
This latent inhibition effect is similar to
habituation - the repeated preexposure to the CS
limits the processing of, or attention to, the
stimulus
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US-preexposure effect
Experiments on the importance of US novelty are
designed in a similar way
Phase 1 Preexposure
Subjects are given repeated presentations of the
US alone
Phase 2 Conditioning
Subjects are given pairings of the CS with the US
The initial preexposure to the US usually retards
subsequent conditioning - may be due to
conditioning of background cues during the
preexposure phase
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CS and US Intensity and Salience
Stimulus salience refers to the significance
or noticeability of the stimulus
Learning occurs more rapidly with more salient,
or more noticeable, stimuli
A stimulus can be made more salient by increasing
the intensity of the stimulus

• A more intense US will usually result in better
• conditioning

• A more intense CS also results in better
• conditioning

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US Intensity
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CS Intensity
A more intense CS also results in better
conditioning
This makes sense from an ecological point of
view - a more intense CS will be more salient
than the background and will command more
attention
With CTA, a stronger concentration of flavor
results in bigger taste aversions - the taste
becomes more different than plain drinking water
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CS Intensity
Overshadowing
If two stimuli are presented together and
followed by a US, will see better conditioning
to the stronger of the two stimuli
TL Shock T loud L weak T better able to
suppress barpressing
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A stimulus can be made more salient by
- increasing the intensity of the stimulus

• making it more relevant to the biological needs
  of the
• animal (i.e., can increase the salience of a salt
  taste by
• depriving the animal of salt)

• making laboratory CSs more similar to stimuli
  animals
• might encounter in the natural environment (i.e.,
  quail)

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Rate of Classical Conditioning is also affected
by
CS-US Relevance, or Belongingness
- the extent to which the CS is relevant to, or
belongs with, the US
The importance of stimulus relevance was
demonstrated in an experiment by Garcia
Koelling (1966)
They compared learning about peripheral pain
(footshock) and learning about illness
In nature, rats are likely to get sick after
eating poisonous food, but experience peripheral
pain after an encounter with a predator
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Garcia Koellings (1966) bright and noisy
water experiment
Phase 2 (test)
Phase 1
Group 1
Sacc LN
LiCl
½ Sacc
½ LN water
Group 2
Sacc LN
Shock
½ Sacc
½ LN water
If taste and sickness go together, then group
given LiCl should have a bigger aversion to
saccharin than to the audiovisual cue (LN)
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Rats that got poisoned decreased saccharin
consumption Rats that got shocked decreased
consumption of the bright and noisy water
This experiment suggests that tastes are more
readily associated with sickness than with shock
(peripheral pain) and that audiovisual cues (LN)
are more readily associated with pain/shock than
with sickness
Selectivity of association
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We see evidence of this selectivity of
association in other species
For ex., certain birds locate food by its visual
characteristics, rather than by its taste
Wilcoxin et al (1970) Trained rats and
quail Taste visual CS paired with poison
Train
Sour Blue
LiCl
Test
½ blue water
½ sour water
Subjects given blue water were being tested for
aversion to color (visual property of food) while
those given sour flavor were being tested for
taste aversion
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Rats showed a strong aversion to the sour flavor
and little aversion to the visual properties of
the food But see opposite pattern in birds
strong aversion to blue water but little
aversion to the sour taste
The CS that is most easily conditioned is the one
that animals use to procure food Rats use taste
and odor cues to procure food Birds use visual
cues to procure food
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The Concept of Biological Strength
Initially, the CS is weaker than the US
But after conditioning, the CS is strong and
elicits a vigorous response
Could the strong CS now serve as a US?
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Higher-Order Conditioning
CS US T Food
This is an example of first-order
conditioning The CS (Tone) will elicit salivation
after a few trials
Now, pair L T
This is an example of second-order
conditioning The second CS (Light) will come to
elicit salivation
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Second-Order Conditioning
CS1
US
CR
CS2
CS1
CR
Money is an example of a powerful CS for humans
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Similarity between Second-order conditioning and
the standard procedure for producing Conditioned
Inhibition
2nd order conditioning CI CS1 US
CS CS2 CS1 CS/CS-

• Important factors
• The number of no-US trials
• - few no-US trials 2nd order conditioning
• - many no-US trials CI
• 2. Pattern of trials
• - 2nd order conditioning sequential
• - CI interspersed

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Examples of Classical Conditioning discussed so
far satisfy the criterion of differential
biological strength - strong US and weaker CS
(1st order conditioning) - strong CS1 and weaker
CS2 (2nd order conditioning)
In some situations, associations form between
stimuli when this condition is not met
1. Counterconditioning
Two stimuli become associated even though both
elicit strong responses
The normal response to the CS is reversed, or
countered, by pairing it with a US that
elicits the opposite response
Shock
Food
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2. Sensory Preconditioning
Two stimuli become associated even though both
are weak
CS2
CS1
CS1
US
CS2
CR
CR
Because both stimuli are biologically weak in the
first stage, there is no robust response to
measure
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Sensory Preconditioning
T L
(No CR to measure)
(L elicits salivation)
L Food
T
(T now elicits salivation)
The procedure for Sensory preconditioning is very
similar to the procedure for 2nd order
conditioning - the 2 phases of conditioning are
reversed
Sensory preconditioning 2nd order conditioning
CS2 CS1 CS1 US CS1
US CS2 CS1