Some definitions.

1.  Unconditioned stimulus (US) = a stimulus that elicits a response without training = food

2.  Unconditioned response (UR) = the response elicited by an unconditioned stimulus = salivating when food placed in mouth

3.  Conditioned stimulus (CS) = a stimulus that through pairing with a US (i.e. after training) elicits a response = tone

4.  Conditioned response (CR) = a response to the CS that occurs as a function of training = salivating to tone after tone (CS) was repeatedly paired with food (US)

(US) FOOD = SALIVATION (UR)

(CS) TONE + FOOD (US)

(CS) TONE = SALIVATION (CR)

5 basic temporal arrangements between the CS & US

1 & 2) DELAY CONDITIONING = the CS comes on first and when still on the US is presented.  2 categorys: SHORT DELAY and LONG DELAY.

3) TRACE CONDITIONING = the CS comes on first then shortly after it terminates the US is presented

4) SIMULTANEOUS CONDITIONING = the CS and US comes on simultaneously

5) BACKWARD CONDITIONING = the US comes on before the CS

A few key discoveries:

1.  SECOND-ORDER (HIGHER-ORDER) CONDITIONING = learning that takes place as a result of the pairing of a stimulus with a previously conditioned stimulus.

(US) FOOD = SALIVATION (UR)

(CS1) TONE + FOOD (US)

(CS1) TONE = SALIVATION (CR)

(CS1) TONE + METRONOME (CS2)

(CS2) METRONOME = SALIVATION (CR)

2.  SENSORY PRECONDITIONING = A procedure in which 2 neutral stimuli are presented together and then one of them is paired with an unconditioned stimulus.  Results typical show that responding is conditioned to both stimuli.

(US) SHOCK = MOVEMENT OF LEG (UR)

(CS1) TONE + LIGHT (CS2)

(CS1) TONE + SHOCK (US)

(CS1) TONE = MOVEMENT OF LEG (CR)

(CS2) LIGHT = MOVEMENT OF LEG (CR)

3.  COUNTERCONDITIONING = in counterconditioning, the response that an animal makes to a stimulus is reversed or "countered" by pairing the stimulus with another US that elicits an opposite response.  Example = in dogs an electric shock (US) is usually followed by an escape response (UR)

but follow the shock repeatedly with food and the dogs almost completely suppressed their escape behavior

4.  PSEUDOCONDITIONING = An increase in responding to the CS due to the presentation of the US by itself.  Example = repeated blasts of air to the eye (US) could render a person jumpy enough that they would blink (UR) whenever any sudden stimulus (CS) was presented.

5.  CONDITIONED INHIBITION = A tendency for a stimulus to inhibit, or block, the response normally elicited by a CS.  There are a number of different procedures but generally the conditioned inhibitor signals that a US (which would have normally occurred) will NOT be presented.

6.  LATENT INHIBITION = Presentations of a stimulus by itself which retards subsequent conditioning to that stimulus.

7.  EXTINCTION = the disappearance of a conditioned response when a CS is presented by itself.

8.  SPONTANEOUS RECOVERY = an increase in the strength of an extinguished response after a period of time following the last extinction trial.

9.  GENERALIZATION = responding to a test stimulus as a result of training with another similar stimulus.

10.  DISCRIMINATION = The differential responding to 2 stimuli following discrimination training.

(CS+) 50 mHz TONE + FOOD (US)

(CS-) 100 mHz TONE + no FOOD

11.  SIGN TRACKING / AUTOSHAPING = Animals will approach and come into contact with stimuli that signal the availability of food.  Example = dogs will push their food bowls across the floor.  In the natural environment, the availability of food is usually signalled by some sort of feature of the food itself -- like visual appearance or odor -- that they can experience from a distance.  By approaching these stimuli and then coming in contact with these stimuli, animals will end up coming in contact with the food -- which, after all is the whole point isn't it?  By TRACKING these stimuli or SIGNS, an animal is likely to get a meal.  SIGN TRACKING is the general term for these behaviors.  AUTOSHAPING is the specific name given to the procedure devised by BROWN & JENKINS (1968).

In order to study the effects of rewards on animal learning researchers had to employ the strategy of SHAPING or rewarding successive approximations to the desired behavior.  Example = pigeons were rewarded for first turning toward the food hopper, then approaching food hopper, then looking at key, then pecking at key

BROWN & JENKINS (1968)

instead of rewarding successive approximations to pecking at the key, Brown & Jenkins employed classical conditioning -- they put the pigeon in the chamber and put a light on the key.  When the light was turned on, the food was automatically delivered -- food was NOT contingent upon any behavior

(CS) LIGHT ON KEY + FOOD (US)

Results = after repeated pairings the pigeons came to direct their behavior toward the lit key -- that is, they paired the lit key with food until the birds pecked at the key.

12.  STIMULUS SUBSTITUTION = Pavlov’s interpretation of the process that occurs during conditioning.  He believed that activation of the CS center of the brain would be transferred to the US center and would therefore elicit the same behaviors as the US.  In his view, the CS essentially becomes the US.

13.  CONDITIONED EMOTIONAL RESPONSE (CER) = a procedure for measuring fear based on the observation that frightened animals usually freeze.  Since frightened animals tend to freeze (especially rats) -- we can measure how long they stay still after the presentation of a stimulus & get an idea of how frightened they are -- freezing is basically incompatible with most other kinds of behavior.

a) Skinner trained rats to bar press for food

b) then repeatedly paired a TONE + SHOCK until the TONE reliably elicited FREEZING

c) rats were allowed to bar press then he introduced the TONE and counted the number of bar presses

SUPPRESSION RATIO= the number of times the rats bar pressed during the TONE compared to how many times the rat bar pressed overall =

RESPONDING DURING THE CS

RESPONDING DURING THE CS + RESPONDING PRIOR TO THE CS

What does it mean to have a SUPPRESSION RATIO equal to "0"?  Total suppression

What does it mean to have a SUPPRESSION RATIO equal to "0.5"? Total responding

14.  TASTE AVERSION LEARNING = a phenomenon in which a subject learns to avoid the taste or odor of a particular food as a result of that food’s association with illness.

Garcia & Koelling (1966) BRIGHT NOISY TASTY WATER experiment

(US) NAUSEA by X-radiation = AVOIDANCE (UR)

(compound CS) BRIGHT-NOISY-TASTY WATER + NAUSEA by Xray (US)

(CS) BRIGHT (no noise, plain water) = NO AVOIDANCE

(CS) NOISY (no bright, plain water) = NO AVOIDANCE

(CS) TASTY WATER (no noise, no bright) = AVOIDANCE (CR)

Alternative explanation = what if the bright/noisy stimuli are not being attended to ... maybe the animals don't even see or hear them ... how would you check for this?

(US) SHOCK = AVOIDANCE (UR)

(compound CS) BRIGHT-NOISY-TASTY WATER + SHOCK (US)

(CS) BRIGHT (no noise, plain water) = AVOIDANCE (CR)

(CS) NOISY (no bright, plain water) = AVOIDANCE (CR)

(CS) TASTY WATER (no noise, no bright) = NO AVOIDANCE

BASIC FINDINGS = YOU CANNOT PAIR ANY CS WITH ANY US and by virtue of the contiguous pairing get learning -- demonstrates the principle of CS-US RELEVANCE or "BELONGINGNESS" -- it definitely matters which CS is paired with which US - CONTIGUITY IS NOT ENOUGH!  Learning depended upon the relevance or appropriateness of the CS to the US.

(compound CS) LIGHT/TONE/TASTE + ILLNESS (US)

ONLY TASTE CUE = AVOIDANCE (CR)

(compound CS) LIGHT/TONE/TASTE + SHOCK (US)

ONLY LIGHT/TONE AUDIO-VISUAL CUE = AVOIDANCE (CR)

15.  BLOCKING = A phenomenon in which prior conditioning to one element prevents conditioning to other elements of a compound.  In modern learning theory, we now have accepted that classical conditioning can involve some information processing -- it's not just simply a mindless S-S or S-R procedure -- there are other things that matter.  Good example = Kamin’s BLOCKING effect.

Standard CER procedure for the CONTROL GROUP:

a) teach rats to bar press for food reward

b) classically condition a fear response

      (US) SHOCK - FEAR/FREEZING (UR)

      (compound CS) NOISE/LIGHT + SHOCK (US)

c) when rats are bar pressing for food test the suppression ratio by presenting the CSs

      (compound CS) NOISE/LIGHT - FEAR/RESPONSE SUPPRESSION (CR)

      (CS) NOISE - FEAR/RESPONSE SUPPRESSION (CR)

      (CS) LIGHT - FEAR/RESPONSE SUPPRESSION (CR)

Kamin’s BLOCKING procedure = the CONTROL group was trained on with standard CER procedure but the BLOCKING GROUP was trained using the procedure below:

a) teach rats to bar press for food reward

b) classically condition a fear response

      (US) SHOCK - FEAR/FREEZING (UR)

      (CS) NOISE + SHOCK (US)

      then (compound CS) NOISE/LIGHT + SHOCK (US)

c) when rats are bar pressing for food test the suppression ratio by presenting the CSs

      (compound CS) NOISE/LIGHT - FEAR/RESPONSE SUPPRESSION (CR)

      (CS) NOISE - FEAR/RESPONSE SUPPRESSION (CR)

      (CS) LIGHT - NO FEAR/NO RESPONSE SUPPRESSION (CR)

Result = PRIOR CONDITIONING TO THE NOISE BLOCKED CONDITIONING TO THE LIGHT

Kamin explained blocking by hypothesizing that when an important event occurs UNEXPECTEDLY (like a shock) animals search their memories to find cues that could help predict the event in the future

a) initially, the US would trigger a memory search for predictive cues

b) for the control group, the compound CS was paired with SHOCK (US) - the unexpected SHOCK would trigger the memory search and find that BOTH light and noise predicted the shock

c) but for the blocking group, noise was paired with SHOCK first then the compound stimulus was used; in this case, the unexpected SHOCK would trigger the memory search and find that NOISE predicted the shock

So, to be effective, Kamin would say that the US has to be UNEXPECTED or SURPRISING.

16.  COMPENSATORY RESPONSES

A key concept in understanding the activity of the autonomic nervous system is HOMEOSTASIS or the activities of the body designed to maintain a stable internal environment or milieu.  Examples = body temperature, blood glucose levels.

Siegel (1972) gave rats a number of injections of insulin = a hormone that decreases glucose levels in the blood.  Pavlov would predict that the cues associated with the injection of the drug would become CSs and come to elicit the systematic effects of the drug.

(US) INSULIN = DECREASED BLOOD GLUCOSE LEVELS (UR)

(CS) INJECTION STIMULI + INSULIN (US)

(CS) INJECTION STIMULI = ? (predicted CR = decreased blood sugar levels)

(CS) INJECTION = INCREASED BLOOD GLUCOSE LEVELS (actual CR)

Siegel suggested that insulin decreased blood glucose levels below an optimal level - when the body senses this drop it COMPENSATES by increasing glucose levels.  It was this homeostatic COMPENSATORY RESPONSE that was conditioned.

Siegel extended his findings to explain DRUG TOLERANCE.  We know that repeated administration of many drugs leads to TOLERANCE = morphine loses its potency -- because of this, we have to increase the dose to produce the same response.  Siegel suggested that tolerance was due to classical conditioning

The theory goes like this = when an injection of morphine reduces pain (analgesia) the body responds with an increased sensitivity to pain (hyperalgesia) to return sensitivity to its appropriate homeostatic level.  Siegel hypothesized that this compensatory mechanism would be conditioned to the cues of being injected

He also found a very interesting tidbit of information HE FOUND OUT THAT THE ROOM SERVED AS A POWERFUL CS

And he used this info to explain heroin overdoses -- and here's how:

a) HEROIN ELICITS COMPENSATORY MECHANISM

b) COMPENSATORY MECHANISM IS CONDITIONED TO ENVIRONMENT WHERE HEROIN WAS ADMINISTERED

c) ADDICT SHOOTS UP IN A NEW LOCATION - OVERDOSE

COMPENSATORY MECHANISM WOULD NOT BE AS STRONG IN NEW ENVIRONMENT BECAUSE CSs WOULD BE ABSENT (OR DIFFERENT) AND EFFECTS OF HEROIN WOULD BE STRONGER.

Siegel interviewed survivors of heroin overdoses and found that 70% of O.D.s occurred when heroin was injected in a different location and confirmed this finding using rats.

a) rats were made dependent upon heroin

b) RATS were GIVEN an OD DOSE (a dose that would ordinarily kill a rat that had never experienced heroin) IN SAME ENVIRONMENT = 32% DIED

c) another group of RATS were GIVEN this OD DOSE IN DIFFERENT ENVIRONMENT = 64% DIED