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Chapter 3: Pavlovian Conditioning: Foundations

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Title: Chapter 3: Pavlovian Conditioning: Foundations


1
Chapter 3 Pavlovian Conditioning Foundations
  • Pavlovian Conditioning or Classical Conditioning
  • Ivan Pavlov
  • Early 1900s
  • A Russian physiologist
  • digestive system
  • Nobel prize
  •  Interested in the Salivary reflex.
  • The reflex seemed to depend on the nature of the
    stimulus.
  • marble little saliva
  • sand quite a lot.

2
  • Sometimes dogs would salivate prior to receiving
    food
  • Puzzling to Pavlov
  • Reflex in the absence of stimulus presentation
  • Psychic secretions
  • How was it possible that experience could alter
    the salivary reflex?

3
  • Pavlov carefully examined the development of
    psychic secretions
  • Eliciting factors?
  • sight and smell of food
  • food bowl
  • lab coats
  • footsteps
  • Dog had associated these visual and auditory
    stimuli with taste?

4
  • Pavlov began to put together a theory
  • Two distinct kinds of reflexes.
  • 1) Unconditional Reflex
  • inborn and unlearned (innate)
  • usually permanent reflex
  • Found in virtually all members of a species
  • varies little from individual to individual.
  • salivary reflex
  • patellar reflex
  • 2) Conditional Reflex
  • must be acquired through experience (not innate)
  • not permanent.
  • varies considerably from species to species
  • Varies from individual to individual.
  • salivating to footsteps.

5
  • Elements of Pavlovian Conditioning.
  • First lets distinguish between excitatory and
    inhibitory conditioning.
  • Excitatory Conditioning
  • Learning that a stimulus predicts the presence
    of another stimulus
  • Pavlovs initial studies
  • Inhibitory Conditioning
  • Learning that the stimulus predicts the absence
    of another stimulus
  • We will discuss this more later
  • Back to Excitatory Conditioning 
  • First Pavlov described the basic reflex
  • e.g., Food elicits salivation
  • Pavlov named the stimuli
  • Unconditioned Stimulus (US) elicits
    Unconditioned Response (UR)

6
  • Conditioned Stimulus (CS)
  • a previously neutral stimulus
  • Pavlovs bell
  • Normally doesnt elicit salivation
  • What response would it elicit?
  • Known as orienting response
  • Pair the Conditioned Stimulus with an
    Unconditioned Stimulus 
  • tone ? food salivation.
  • CS ? US UR
  •  
  • After several CS ? US pairings
  • Test to see if learning occurred
  • How?
  • Test with CS alone
  • Look for Conditioned Responding (CR)
  • CS now elicits CR

7
  • Lets go through an example in more detail
  • consider Empiricists rules of association
    (chapter 1)
  • Saliency
  • CS
  • Tone
  • 10 seconds
  • 500Hz
  • 70 db
  • US
  • 5.0 gm meat powder
  • Contiguity
  • CS-US interval 20 seconds (from offset of the
    CS to the onset of the US)
  • Intertrial Interval 10 minutes (also can have
    effects on contiguity)
  • Frequency
  • trials 60 (frequency of associations or
    number of trials can affect strength of
    conditioning
  • Test every 10th trial

8
  • Lets look at how the findings might have come
    out
  • Graph
  • Y axis?
  • X axis?
  • Baseline

9
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10
  • Control Groups?
  • Typically a learning experiment uses control
    groups.
  • In the hypothetical Pavlovian experiment we have
    been discussing thus far, we already have a
    control condition.
  • Baseline measurement
  • Is that enough?
  • What other controls would be important?
  •  A group that receives the tone alone.
  • CS alone control -
  • A group that receives the meat powder in the
    absence of the tone.
  • US alone control
  • Any increase in salivation in these control
    groups can be viewed as non-contingent learning.
  • Sensitization?
  • The US (meat powder) alone group may be
    particularly important to rule out any unintended
    cues that indicate reinforcement is about to
    occur.
  • Confounds

11
  • What other controls might be appropriate?
  • Maybe just experiencing bells and food sensitizes
    the animal and gets them drooling.
  • Either one alone is not enough, but both creates
    sensitization
  • Remember 12 checks vs. 4 checks in infant study
    (chapter 2)
  • How can we control for this?
  • Three ways
  • 1) Backward Conditioning control
  • US?CS
  • may cause conditioning (learning).
  • What kind?
  • Known as inhibitory (we will discuss this more
    later)

12
  • 2) Random control
  • The CS and US occur randomly
  • Sometimes the CS will precede the US
  • equally often the US will precede the CS.
  • Also the temporal relationship between the CS and
    US varies
  • Seems it should prevent association of tone and
    food
  • Nevertheless sometimes the animals still
    associate
  • 3) Explicitly unpaired control
  • Present CS and US on separate trials
  • Length of ITI necessary - varies depending on
    task
  • Must be long (i.e., 24 hours for CTA)
  • There is some debate about whether random or
    explicitly unpaired controls are best
  • Some form of learning seems to occur in all
    situations

13
  • conditioning a patellar reflex?
  • E. B. Twitmeyer (1902)
  • PhD thesis at University of Pennsylvania
  • Zeitgeist
  • CS?
  • Tone
  • US?
  • Tap knee
  • UR?
  • Kick
  • When?
  • CR?
  • Kick
  • When?

14
  • An introduction to contemporary conditioning
    methods
  • There are many ways to examine Classical
    Conditioning
  • Its not all slobbering dogs
  • Fear Conditioning
  • Little Albert
  • Watson and Raynor
  • Conditioned Emotional Response
  • Aversive Conditioning vs. Appetitive Conditioning

15
  • Fear Conditioning in animals?
  • How do we measure fear?
  • Freezing behavior?
  • How do you quantify it?
  • Would be nice to have initial activity to serve
    as a baseline
  • Conditioned Suppression procedures
  • lick suppression procedure
  • Water deprived
  • Measure licks on water bottle
  • Present fear stimulus
  • slows licking
  • Conditioned Emotional Response procedure
  • Phase 1
  • Train rat to press lever to receive food.
  • Phase 2
  • Pair tone with shock
  • Test

16
  • Often use Suppression Ratio as Dependent Variable
  • CS responding / (CS responding pre-CS
    responding)
  • Suppression ratios vary from 0 (complete fear) to
    .50 (no fear at all)
  • Lower suppression ratio more fear
  • 0/(010) 0 ? complete fear
  • 1/(1 10) .09 ? almost complete fear
  • 10/(1010) .50 ? no fear at all

17
  • Conditioned eye-blink procedure.
  • Often rabbits
  • but has also been shown in rats and humans.
  • also aversive conditioning.
  • CS, US, UR, CR?

18
  • Taste Aversion Conditioning
  • novel flavor (CS often saccharin or chocolate
    milk)
  • CS?
  • Taste
  • US?
  • LiCl
  • UR?
  • Illness
  • CR?
  • Illness
  • How do you measure this?

19
  • Conditioned Taste Aversion
  • one-trial learning
  • long-delay learning
  • Eye-blink takes many many trials to learn
  • Why the large difference?
  • Preparedness to learn?

20
  • Sign Tracking (AKA autoshaping)
  • Brown and Jenkins (1968)
  • Key light reliably predicts food Operant
    Chamber
  • 8 second Key light then Food
  • How do you think the pigeons behaved?
  • Pigeons pecked the key
  • remember pecking was not required
  • The Long Box Study Hearst and Jenkins (1974)
  • Three feet long
  • Key at one end
  • Food at the other
  • Video

21
  • Temporal factors in conditioning
  • Short Delayed Conditioning
  • CS onset shortly precedes (less than a minute) US
    onset.
  •  
  • Trace conditioning
  • a lag between CS offset and US onset.
  • closer stronger the conditioning will be
  • too long no conditioning
  •  
  • Long delayed Conditioning
  • CS onset occurs 5-10 minutes before US onset

22
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23
  • Simultaneous conditioning
  • CS and US occur simultaneously
  • ultimate in contiguity.
  • weaker conditioning than above
  •  
  • Backward Conditioning
  • US offset occurs simultaneously with CS onset.
  • Another example of contiguity of stimuli,
  • Excitatory Conditioning?
  • often results in inhibitory conditioning.
  • What if CS tone and US shock?
  • How would you recognize inhibitory conditioning?
  • Safety behaviors
  • Increased activity during CS

24
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25
  • Inhibitory Conditioning
  • Backward US-CS pairings tend to cause inhibitory
    conditioning.
  • less-than-normal salivation if food precedes the
    bell
  • activity safety if the shock precedes the bell

26
  • Induction Method for producing conditioned
    inhibition (Pavlovs Procedure)
  • Can be examined using the conditioned suppression
    procedure
  • After training the rats to barpress for food you
    could introduce Pavlovs induction method.
  • Half of trials are excitatory conditioning trials
    (type A)
  • CS(tone)?US (shock)
  • Other half of trials are inhibitory conditioning
    trials (type B)
  • CS(tone) and CS-(light) ? nothing
  • Each day they receive both types in a random
    order (say 30 of each)
  • What should responding be like
  • During CS alone presentations?
  • During CS and CS- presentations?
  • During CS- alone?

27
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28
  • The negative contingencies procedure (aka -
    explicitly unpaired)
  • Another way of producing conditioned inhibition
  • This time there is only one CS though
  • Presentations are organized such that the US
    never follows the CS closely in time

29
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30
  • Heth (1976) examined negative contingencies
  • conditioned suppression procedure
  • trained rats to barpress for food.
  • Then 60 negative contingency pairings.
  • Tone and shock
  • This procedure resulted in the rats first fearing
    the tone in early trials.
  • How would he know?
  • SR close to 0
  • Later as the animal had more experience with the
    tone and shock, he found a safety response in the
    presence of the tone.
  • How would he know?
  • SR close to .50

31
  •  The induction method (Pavlovs procedure) and
    negative contingencies are good ways to examine
    Conditioned inhibition
  • if you are measuring behaviors that can be both
    increased and decreased
  • Bar Pressing
  • Sometimes, however, there is such a small amount
    of initial behavior that it cannot be decreased.
  • Under these circumstances special procedures are
    needed to examine conditioned inhibition.

32
  • Indirect methods for measuring conditioned
    inhibition.
  • Lets say that you have been running an experiment
    where you repeatedly present food (US) followed
    by a bell (CS) to dogs.
  • backward conditioning.
  • What behavior would you expect from the dog
    toward the bell?
  • no salivation.
  • Dogs, however do not salivate to bells normally
    anyway.
  • how would you know that the bell was inhibiting
    responding, rather than just being ignored?
  • Two procedures
  • Summation test
  • Retardation test.

33
  • In the summation test an animal is trained in two
    ways.
  • 1) they are trained that one (CS-) is a
    conditioned inhibitor using backward
    conditioning.
  • US(food)? CS1- (bell)
  • 2) they are trained that a second (CS) is a
    conditioned excitor
  • CS2( light)?US(food).
  • summation group
  • train US (food)?CS1- (bell)
  • CS2(light)?US(food)
  • test CS1- and CS2
  • Salivation to CS1?
  • Salivation to CS2?
  • Salivation to CS1- and CS2?
  • Note increasing the baseline (by conditioning
    salivation) allows us to see this
  • It is also interesting in its own right
  • independent learning about CSs and CS-s can
    summate

34
  • Retardation test
  • this is a simple idea
  • it should be more difficult to train an
    excitatory response to a stimulus that has become
    a conditioned inhibitor than it would be to one
    that has not become a conditioned inhibitor
  • retardation gp control
  • phase 1 US(food)?CS(bell)
  • phase 2 (10 tr) CS(bell)?(food)
    CS(bell)?(food)
  • test CS alone
    CS alone
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