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

2. Procedures for Measuring CI
Directed Behavior Test
Summation (Compound Stimulus) Test
Retardation-of-Acquisition Test

3. 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?

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. US Intensity

11. 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

12. 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

13. 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)

14. CS-US Relevance, or Belongingness
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

15. “bright and noisy water” experiment
Garcia & Koelling’s (1966)
“bright and noisy water” experiment
Phase 1
Phase 2 (test)
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)

17. 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

18. 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

20. 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

21. 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?

22. 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

23. Second-Order Conditioning
CS1 US CR
CS2
CS1 CR
Money is an example of a powerful CS for humans

24. Similarity between Second-order conditioning
and the standard procedure for producing
Conditioned Inhibition
2nd order conditioning CI
CS US CS+
CS 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

25. 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

26. 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

27. Sensory Preconditioning
T L
(No CR to measure)
L Food
(L elicits salivation) 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
CS CS1 CS US
CS US CS CS1