Last class

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Psychology 2250
Last class Definition of learning Distinction
between learning and performance Habituation and
Sensitization Dual-Process Theory S-R
system State system
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Habituation and Sensitization
Characteristics of Habituation and
Sensitization Time course Sensitization is
usually temporary -sensitization can last for up
to a week but not generally a long-term effect.
-with a stronger stimulus, the effects last
longer.
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Habituation can be short-term or long-term,
depending on presentation and interval between
stimuli.
Short-term habituation -rapid presentations of
a stimulus with a short interval between
presentations -results in habituation quickly
but see spontaneous recovery -the degree of
spontaneous recovery depends on length of rest
interval.
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Long-term habituation -one stimulus
presentation a day -see more long-term
effects -see less spontaneous recovery
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Leaton, 1976 see page 46 of Domjan
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Stimulus specificity Habituation is
stimulus-specific -if you change the stimulus,
see recovery of the response Sensitization is
not highly stimulus-specific -if an animal is
aroused, it is usually aroused to a variety of
cues
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Effects of strong extraneous stimuli If you
change the nature of the eliciting stimulus you
see recovery of the habituated response. Can
also see recovery of the response if the animal
is given a rest period spontaneous
recovery. The response can also be restored by
presenting a strong stimulus this is called
dishabituation. Dishabituation refers to
recovery of the response to the habituated
stimulus following presentation of a different,
novel stimulus.
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Habituation and Sensitization in Aplysia
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Habituation of the gill withdrawal reflex results
from changes in the S-R pathway
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Dishabituation/Sensitization
After the gill withdrawal reflex has habituated,
a shock to the tail sensitizes the gill
withdrawal reflex elicited by touching either
the mantle or siphon Dishabituation is a case of
Sensitization
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Sensitization (dishabituation) occurs because
tailshock augments the release of
neurotransmitter from the sensory neuron
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The Opponent-Process Theory of Motivation
(Solomon and Corbit, 1974)
The concepts of habituation and sensitization
have been extended to emotions and motivated
behavior
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Common characteristics of emotional reactions 1.
Emotional reactions are biphasic a primary
reaction is followed by an opposite
after-reaction 2. The primary reaction becomes
weaker with repeated stimulations 3. The
after-reaction is strengthened
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The Opponent-Process Theory is a homeostatic
theory The theory assumes that
neurophysiological mechanisms involved in
emotional behavior serve to maintain emotional
stability
Drug-seeking behavior
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a-b
a-b
a
a
b
b
Time
First Presentation of Arousing S
After Many Presentations of Arousing S
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Classical Conditioning or Pavlovian conditioning

• Ivan P. Pavlov
• was a Russian physiologist who accidentally
  discovered this type of learning
• he was studying the physiology of digestion when
  he noticed
• a funny thing.
• digestion starts in the mouth where saliva begins
  to break
• down food. Dogs would salivate when he put the
  food powder
• in their mouths.
• But experienced dogs would also salivate when the
  experimenter
• walked in the room or at the sight of food.

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An apparatus for Pavlovian conditioning. A tube
carries saliva from the dogs mouth to a lever
that activates a recording device (far left).
During conditioning, various stimuli can be
paired with a dish of food placed in front of the
dog. The device pictured here is more elaborate
than the one Pavlov used in his early
experiments.
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Pavlov paired the clicking of a metronome with
food. Clicker Food (never used a
bell) Dogs normally salivate with food but not
with the clicker
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After a few of these pairings, dogs began to
salivate when the metronome came on.
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The first stimulus (clicker) triggered the
memory (or anticipation) of the second stimulus
(food). Thus, we can say the 2 events have
become associated.
Association If 2 sensations, or stimuli,
repeatedly occur together, the mental reactions
to those stimuli become associated such that
when the first sensation or stimulus is given,
it triggers the memory of the associated
stimulus. Those of you with pets will have
already seen this phenomenon in action.
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• Formal definition of Pavlovian conditioning
• 2 stimuli occur together regardless of the
  subjects
• behavior
• in Pavlovs original experiment, food was given
• even if the dogs didnt salivate to the clicker.
• In this type of conditioning we set up
  conditions,
• or pairings, beforehand and present them
  regardless
• of the subjects behavior.
• Decide on clicker food pairings and then
  present
• them a of times regardless of what the animal
  does to
• the clicker.

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Four major terms apply to Pavlovian Conditioning
experiments
Stimuli
Responses
UR Unconditioned response The unlearned response
triggered by the US Powerful and reflexive
(i.e., salivation to food)
US Unconditioned stimulus Biologically potent
stimulus that reliably evokes an unlearned or
reflexive reaction (i.e., food)
CR Conditioned response It is elicited by the CS
and represents the learned behavior The
behavioral manifestation of the underlying
association between the CS and the US (i.e.,
salivation to the Metronome)
CS Conditioned stimulus Biologically weak
stimulus The CS may evoke an orienting response,
but not the strong response evoked by the US
(i.e., metronome)
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Pavlovs original experiment is an example of
Excitatory classical conditioning. Excitatory
means the CS is able to excite the CR into being.
From a procedural point of view, conditioned
excitation, or excitatory conditioning occurs
when presentation of the CS is followed by a
presentation of the US (i.e., CS US
pairings).
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Two types of Excitatory Conditioning Appet
itive Aversive CS is followed by an CS
is followed by an appetitive (good) US
aversive US (i.e., food, water, mate) (i.e.,
mild shock, illness)