Conditioned Inhibition - Memorial University of Newfoundland
Conditioned Inhibition Procedures for producing CI Conditional (standard) Procedure Negative Contingency/Explicitly Unpaired Differential Procedure Backward Conditioning Long-delay/Trace Conditioning
Procedures for Measuring CI Directed Behavior Test Summation (Compound Stimulus) Test Retardation-of-Acquisition Test 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?
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 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 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 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 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 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 US Intensity Flavor LiCl See bigger aversion in the group that got the high dose of LiCl (i.e., more intense US) Cons
Low dose High dose 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 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 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) 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 Garcia & Koellings (1966) bright and noisy water experiment Phase 2 (test)
Phase 1 Group 1: Sacc + LN LiCl Sacc LN + water Group 2: Sacc + LN Shock
Sacc 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) Sacc LN Cons LiCl
Shock 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
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: blue water 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 Sour water Blue water Cons Rats Quail 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 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?
Higher-Order Conditioning CS T US 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 Second-Order Conditioning CS1 US CR CS2 CS1 CR
Money is an example of a powerful CS for humans Similarity between Second-order conditioning and the standard procedure for producing Conditioned Inhibition 2nd order conditioning CS1 US CS2 CS1 CI
CS+ CS+/CS- Important factors: 1. 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 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
2. Sensory Preconditioning Two stimuli become associated even though both are weak CS2 CS1 CS1 US CR CS2
CR Because both stimuli are biologically weak in the first stage, there is no robust response to measure 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 CS2 CS1 CS1 US CS1 US CS2 CS1
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