Transcript Underlying Processes in Classical Conditioning

Underlying Processes in Classical
Conditioning
Theory
S-S vs. S-R Models of
Conditioning
• S-S Learning = Stimulus-Stimulus
• The CS becomes directly associated with the US
• Therefore, the CS comes to elicit a response that is
similar / related to the US
• S-R Learning = Stimulus-Response
• The CS becomes directly associated with the UR
• Therefore, the CS comes to elicit the same response
as the UR
S-S vs. S-R Models
• The research conducted to test whether
classical conditioning is based on S-S or
S-R learning has found evidence to support
both positions (not usually in the same
study :)
• Currently, there tends to be a heavier
emphasis on study of S-S associations
S-S Approaches
• One example is Pavlov’s stimulussubstitution theory
– The CS acts as a substitute for the US
– A connection forms in the brain between the CS and the
US activation sites
– When the CS is activated alone following acquisition, it
will automatically activate the US site in the brain
– Therefore, the CR should be almost identical to the UR
(because the connection between UCS and UR in the
brain is hardwired)
Evidence in support of the stimulus
substitution hypothesis
• Jenkins & Moore (1973) study:
– Autoshaping in pigeons
– One group had CS(light)-->US(grain)
• Photos showed pigeons trying to “eat” the lit
key (open beak and closed eyes) when they
pecked
– 2nd group had CS(light)-->US(water)
• Photos showed pigeons trying to “drink” the
lit key (closed beak and open eyes) when
they pecked
Jenkins & Moore (1973)
Left = Water
Right = Grain
Evidence against the stimulus
substitution hypothesis
• Any study in which the elicited CR is
different from the UCR
e.g., when a tone is paired with shock, rats will
jump to the UCS (shock), but the CR is
typically freezing
e.g., when a light is paired with food, rats will
rear to the light (CR) but the UCR is approach
to the food dispenser
Preparatory Response Model
• Kimble’s (1961, 1967) theory proposed that
the CR is a response that serves to prepare
the organism for the upcoming UCS
e.g., following acquisition of CRs in eyeblink
conditioning, the CR eyeblink may actually
prepare the person for the upcoming airpuff
such that the eye would be partially closed
when the airpuff occurs
Compensatory-Response Model
• The compensatory-response model is one
version of preparatory-response theory
• In this model of classical conditioning, the
compensatory after-effects to a US are what
come to be elicited by the CS
• Based on the opponent-process theory of
emotion / motivation
Opponent-Process Theory of
Emotion (Solomon & Corbit, 1974)
• Emotional events elicit two competing
processes:
– The primary- or A-process that is immediately elicited
by the event
• e.g., taking an exam elicits an unpleasant A-state
– An opponent- or B-process that is the opposite of the Aprocess and counteracts it
• e.g., the pain during the exam (A-state) creates a
pleasant relief response (B-state) following the exam
Properties of the A and B
processes
• A-process
– magnitude &
duration of the
A-state are
determined by the
stimulus event
– magnitude &
duration are fixed
(no change with
experience)
• B-process
– dynamic; changes with repeated
exposure
– with repeated exposure the Bstate begins earlier, has greater
magnitude, & lasts longer
– if time passes without exposure,
the changes in the B-state
reverse
– Changes due to repeated
exposure depend upon short
delays between presentations
Underlying Opponent Processes
Stimulus
a-state
• First few stimulations
b-state
Stimulus
a-state
b-state
• After several
stimulations
Opponent-Process Theory of
Emotion
• The actual emotional state of the organism
is determined by the difference in
magnitude between the 2 states:
– The A-state minus the B-state = end emotional
result
– If A-state > B-state, then the emotion
experienced will be A-like
– If B-state > A-state, then the emotional result
will be B-like
Resultant Emotional State
Stimulus
a-state
b-state
Stimulus
a-state
b-state
• First few
stimulations
• After many
stimulations
Evidence for a CompensatoryResponse Model
• Siegel (1972) gave rats repeated injections of
Insulin
– Insulin’s effects are to reduce the level of
glucose in the blood
• Tested by giving the rats an injection of
saline (instead of insulin)
– Measured the CR (change in blood glucose
levels)
Siegel (1972) Results
• There was a strong CR that occurred,
but it was an INCREASE in blood
glucose levels
– (The opposite of Insulin’s direct effect)
• CR ≠ UR, and the CR was definitely
compensatory
More Evidence in Support of the
Compensatory-Response Model
• Conditioned morphine tolerance (Siegel,
Hinson, & Frank, 1978)
– Experimental Group: CS (light change &
noise reduction) paired with US
(injection of morphine) for 9 days
– Unpaired Control Group
– Placebo Control Group (CS paired with
injection of saline)
Siegel et al. Results (Conditioned
Drug Tolerance)
• Test: present CS,
inject every rat with
morphine, & place
each rat on a
moderately hot
surface
Mean Latency to Lick Paw
45
40
35
30
25
20
15
10
5
0
Saline
Paired
Unpaired
– Measure latency to lick
their paws
– The faster they lick, the
quicker they feel the
pain
Challenges to the CompensatoryResponse Model
• Eikelboom & Stewart (1982) found that the CR
was much like the response to the drug itself (UR)
with both opiates like morphine and with
stimulants such as cocaine and d-amphetamine.
• It has been argued that conditioned tolerance
effects could be due to habituation of the direct Aprocess rather than being due to classical
conditioning of the opponent B-process.