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.

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?

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?

Elements of Pavlovian Conditioning. First let’s distinguish between excitatory and inhibitory conditioning. Excitatory Conditioning –Learning that a stimulus predicts the presence of another stimulus –Pavlov’s 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)

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.

Conditioned Stimulus (CS) –a previously neutral stimulus Pavlov’s bell Normally doesn’t 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

Let’s 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 10 th trial How do we test?

Let’s look at how the findings might have come out Graph –Y axis? –X axis? Baseline

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

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)

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

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?

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

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 –Introduce tone while rat is lever pressing for food

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/(0+10) = 0  complete fear 1/(1 + 10) =.09  almost complete fear 10/(10+10) =.50  no fear at all

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

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

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

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 –VideoVideo

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

–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

Inhibitory Conditioning Backward US-CS pairings tend to cause inhibitory conditioning. –No salivation if food precedes the bell –activity “safety” if the shock precedes the bell

Conditioned inhibition can be difficult to measure\ –such a small amount of initial behavior that it cannot be decreased. saliva –special procedures are needed Summation test Retardation test

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)  CS 1 - (bell) 2) they are trained that a second (CS+) is a conditioned exciter CS 2 +( light)  US(food). Need at least two groups summation group Control train US (food)  CS 1 - (bell) CS 2 +(light)  US(food) CS 2 +(light)  US(food) test CS 1 - and CS 2 + CS 1 - and CS 2 + Salivation to CS 1 ? Salivation to CS 2 ? Salivation to CS 1 - and CS 2 +? Note – increasing the baseline (by conditioning salivation) allows us to see this –It is also interesting in its own right –independent learning about CS + s and CS - s can summate

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 gpcontrol phase 1 US(food)  CS(bell) phase 2 (10 tr) CS(bell)  (food) CS(bell)  (food) test CS alone CS alone