pavlovian conditioning basic principles thomas g. bowers, ph.d. penn state harrisburg
TRANSCRIPT
Pavlovian Conditioning
Basic Principles
Thomas G. Bowers, Ph.D.
Penn State Harrisburg
Development of a Conditioned Reflex
CSUCS
UCR
CS
UCS
UCR
Development of a Conditioned Reflex
• Onset of CR advances to the onset of the CS
• CR does not exactly mimic the UCR, but generally closely resembles the UCR
Conditioned Fear Responses
• If the UCS is a brief noxious stimuli (such as an electric shock) conditioned fear can result
• Includes increase in heart rate, respiration, tension, urination and so on
• Also called conditioned emotional response (CER) or conditioned suppression
Conditioned Fear Responses
• CER can suppress a well developed operant
• Suppression ratio
Rate Csa_______________________
Rate CSa + Rate CSb
Autoshaping
• Automatic shaping of key pecking or similar behavior
• Key pecking is elicited after successive trials of lighting key just before food delivery
Autoshaping
• Similar to Breland & Breland’s difficulty with shaping Racoon behavior
• Also described as sign tracking
Taste Aversion Learning
• Research by Gracia and Koelling (1966)
• Posed a paradox in our understanding of behavior
• Animals appearing to optimally learn some relationships, but to not managed to learn to other stimulus relationships
Taste Aversion Learning
0
50
100
150
200
250
Licks per minute
Pret
est
Post
test
Period
Learning to Poison
Taste
Light+Noise
Taste Aversion Learning
050
100150200250300350
Licks per minute
Pret
est
Post
test
Period
Learning to Noise
Taste
Light+Noise
Why Is Learning Selective?
• There can be learning to non-optimal temporal contiguity
• Yet no effective learning to more optimal temporal relationships
• Sometimes described as an associative bias
Inhibition and Excitation
• Most conditioning we discuss is excitatory in nature
• Extinction was thought to develop an inhibition of the conditioned response rather than a simple erasure of the CS-UCS connection
Methods to Detect Inhibition
• Presentation of a novel stimulus during extinction of of CS-UCS relationship should result in a CR
• This process is described as disinhibition, and the response returns in a full blown fashion
• Summation Test
Methods to Detect Inhibition
• Compound stimuli where a stimulus predicted safety should be able to reduce conditioned fear
• Resistance to reinforcement test - Previous training to a neutral stimulus should develop inhibition, and hence take longer to acquire a CR
Conditions Producing Inhibition
• Extinction
• Inhibition and delay– In delay conditioning, the CR tends to occur
only in the later part of the CS– Presenting a novel stimulus early in the CS
will result in increased CR
Conditions Producing Inhibition
• Discrimination and Generalization
• Process of distinguishing between CS+ and CS-, where CS+ signals the UCS is coming while CS- predicts the UCS will not be available
Conditions Producing Inhibition
% of CR
Trials
CS-
CS+
Discrimination Gradient
% of CR
600 700 900 1KHz
CS+
Inhibitory Gradient
% of CR
600400 450 550 nm
Light wavelength CS-
Conditioned Inhibition
• Backward conditioning– Recall that if UCS precedes the CS, then
conditioning does not occur– However, the CS becomes a conditioned
inhibitor
What Is Learned in Conditioned Inhibition?
• S-S associations?
• S-R associations?
• CS appear to be “occasion setters”