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 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)

6. 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

7. 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 10th trial • How do we test?

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

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 • It’s 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 • Introduce tone while rat is lever pressing for food

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/(0+10) = 0  complete fear • 1/(1 + 10) = .09  almost complete fear • 10/(10+10) = .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

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

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 (Pavlov’s Procedure) • Can be examined using the conditioned suppression procedure • After training the rats to barpress for food you could introduce Pavlov’s 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?

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

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 (Pavlov’s 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 CS+s 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 gpcontrol • phase 1 US(food)CS(bell) • phase 2 (10 tr) CS(bell)(food) CS(bell)(food) • test CS alone CS alone