Classical Conditioning

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Classical Conditioning

• Excitatory and Inhibitory Conditioning

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Excitatory Conditioning

• CS is paired with a UCS (on some trials)
• UCS may be appetitive or aversive
• CS comes to elicit the CR
• Examples
• Pair a tone with food, animal will begin to
  salivate to the tone
• Pair a light with shock, animal will display fear
  to the light

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Acquisition of Eyeblink CR
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Inhibitory Conditioning

• CS is paired with the absence or removal of the
  UCS
• UCS may be appetitive or aversive
• CS comes to inhibit the CR
• Extinction is one example

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Phases of Conditioning

• Acquisition the phase involving developing and
  strengthening the conditioned response. The
  association is absent at the beginning of
  acquisition and present by the end of
  acquisition.
• Extinction the phase involving presenting the
  CS without the UCS. The association is present
  at the beginning of extinction and weakened or
  absent by the end of extinction.

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Extinction
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Is it Inhibition?

• Couldnt extinction just be unlearning or loss
  of the excitatory association?
• Pavlov attributed it to inhibition of the
  excitatory connection because of the phenomenon
  of Spontaneous Recovery

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Spontaneous Recovery
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How to Measure Inhibition?

• How do we distinguish the presence of inhibition
  from the absence of excitation?
• We assume that excitation and inhibition interact
  with one another so establish excitation, then
  present an inhibitory stimulus, and VOILA

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External Inhibition

• Light CS is paired with food (UCS)
• Dog salivates (CR) to Light reliably
• During one presentation of the CS, present a
  novel Tone and salivation will cease abruptly
• Pavlov attributed the effect to the new stimulus
  inhibiting ongoing neural processes

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DisInhibition

• Following acquisition, Pavlov initiated
  extinction
• During the extinction trials the dog stopped
  salivating to the Light CS.
• Pavlov now presented a new, novel stimulus, e.g.,
  a Clicker during the CS.
• The dog salivated, suggesting inhibition of
  inhibition, or Disinhibition.

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Detecting Inhibition

• Retardation of Learning Technique
• First Phase CS is paired with the absence of
  the UCS inhibitory conditioning
• Second Phase Use the same CS for excitatory
  conditioning pair it with a UCS
• Results Slower acquisition of the new
  conditioning in Phase 2

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Retardation of Excitatory Learning Example

• Experiment by Tomie Kruse, 1980
• 1st Phase
• Autoshaping in pigeons
• Exper Green Light CS Vertical White line CS
  
• Control Green Light as CS Red Light as CS-
• 2nd Phase
• Use CS for Exper group as the CS (V) paired
  with food for both groups

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Pigeon in Operant Chamber
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Detecting Inhibition

• A direct method for measuring inhibition
• Give organism inhibitory training
• Then measure withdrawal from CS- or lack of
  contact with CS-

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Direct Measure of Inhibition Example

• Hearst Franklin, 1977
• Pigeons tested in a box with a tilted floor
• CS- (lit key for 20 sec) predicted no food
• Ratio of time spent on side of box with key
  relative to total time in box
• 0 total avoidance, .5 unaffected, 1.0 total
  approach

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Summation Test to Measure Inhibition

• Hammond, 1967
• Phase 1 rats, press lever for food
• Separately
• CS ? Shock and CS- ? Nothing
• CER test present CS- while lever pressing

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CER Procedure Conditioned Emotional Response

• One Phase teach organism to perform some
  response (e.g., lever pressing in rats)
• Separate Phase Classical conditioning (e.g.,
  tone paired with a mild shock)
• Third Phase Present tone CS while the rat is
  lever pressing measure change in rate of
  behavior as a suppression ratio

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Suppression Ratio

• Suppression Ratio __A__
• A B
• A number of responses during CS
• B of responses prior to CS (same amount of
  time)
• 0 total suppression of ongoing behavior
• 0.5 no change in behavior
• 1.0 doubling of the behavior

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Summation Tests of Conditioned Inhibition
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Procedures to Produce Inhibition

• Conditional CS? UCS CSCS- ? No UCS
• Differential CS? UCS CS- ? No UCS
• Explicitly unpaired CS-? No UCS UCS
• Backward UCS? CS
• Trace conditioning with a large gap