principles and applications of classical conditioning chapter 4 1

PRINCIPLES AND APPLICATIONS OF CLASSICAL CONDITIONING

Chapter 4

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Example: “Bell” and Food

CS

US

URCR

Later Trials

CS

US

UR

First Few Trials

TimeCS = bellUS = foodUR = salivation

CR = salivation

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Central Players

Conditioned Stimulus (CS)

Unconditioned Stimulus (US or UCS)Initially “potent” – Initially elicits a response (inside or outside)

Initially “neutral” – Does not initially trigger same response as does the US

Lights, sounds, tastes, odors, etc.

After pairings with the US, elicits a conditioned response

Food USHunger (inside and hidden)Salivation (outside and observable)

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1.What are the CS and US?

A pigeon pecks a light that signals the presentation of food

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Form of the CR

From Jenkins & Moore, 1973

US = Water (note the closed beak)

US = Food (note the open beak)

video

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Autoshaping (Sign Tracking)

When a localized CS and an “appetitive” US are paired, a CR is sometimes directed at the CS .

PigeonsCR: peck key light CS

Rats

key light CS food US

insert lever CS food USCR: lick lever

• Long-box autoshaping• Omission training

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Goal TrackingWhen a localized CS and a “appetitive” US are paired, a CR is sometimes directed at the site of the US.

Rats tone CS food USCR: check food magazine

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Conditioning of Hunger9

UCS: taste and smell of food UCR: internal physiological changes that

prepare us to digest and metabolize food e.g., secretion of saliva, gastric juices, insulin

Important: insulin lowers blood sugar, which stimulates hunger, which motivates eating

CS: Kitchen, refrigerator, sight of food, Tim Horton sign

CR: Hunger as a conditioned response

Conclusions

1. Conditioned behaviour is “evoked” by the CS, it is not “chosen” by the organism

2. The situation, species, and procedures used can affect whether animals what the animal does.

3. Internal states can cause approach to the CS or the US in appetitive conditioning.

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The Conditioning of Fear11

Conditioning of internal states motivate avoidance of the CS or the US in aversive conditioning

Escape FreezeFlight/Flinch

USCS

Some Specific Conditioned Responses

Time

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Conditioned emotional response Stage 1: Animal must first learn to bar

press for reward Stage 2: A neutral stimulus (CS) is paired

with an aversive stimulus (UCS) Stage 3: The CS is presented during

operant responding Conditioned fear, and specific conditioned

responses, such as freezing, will cause the animal will reduce or stop responding

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The level of fear is assessed with a suppression ratio Suppression ratio =

CS responding/(CS responding + Pre-CS responding)

Interpretation of a suppression ratio Values can range from 0 to 0.5 0.5 means that fear conditioning has not

occurred 0 indicates total conditioning

Conclusions 4. Conditioning of internal states

motivates avoidance of the CS or the US in aversive conditioning

5. Form of CR changes with ISI (This is why conditioned suppression catches them all)

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2. What are the CS and US?16

Garcia Effect17

The classic Flavor Aversion Experiments were conducted by Garcia et al. (1957) Although rats generally like saccharin very

much, they found that rats would not consume saccharin if illness followed its consumption

The illness did not result from the saccharin, though, but rather from either high doses of irradiation or from doses of Lithium Chloride

Taste Aversion18

Flavor Aversion Learning19

Flavor aversion: avoidance of a flavor that precedes an illness experience

Flavor aversion develops rapidly Often after one pairing of flavor and illness May occur even if there is a long time

interval between the flavor and the illness

Aversion as CR Negative state Not conditioned illness May involve a conditioned disgust

reaction

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Conclusions

6. What constitutes a “pairing” depends on the response system (There is no “optimal ISI”)

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3. What are the CS and US?22

Eye Blink Conditioning23

Procedure: CS: tone UCS: puff of air/paraorbital shock CR: blink UCR: blink

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Noteworthy characteristics: UCR and CR differ slightly

UCS elicits a rapid eyeblink response CS produces a slow, gradual closure of the eye

Eyeblink conditioning is slow It may take up to 100 CS-UCS pairings to

produce responding on 50% of trials

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Diagnostic tool27

4. What are the CS and US?

An addict goes into severe withdrawal after seeing the dealer’s door

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Trial 1

Euphoria

Dealer, copping corner, corner syringes, needles, cotton balls, lighters, rubber tying-off cords and stainless-steel spoons

Pre-Drug CSs Drug US

heroin

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Trial 5

heroinEuphoria

Pre-Drug CSs

Dealer, copping corner, corner syringes, needles, cotton balls, lighters, rubber tying-off cords and stainless-steel spoons

Pre-Drug CSs Drug US

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Trial 10

heroin

Dealer, copping corner, corner syringes, needles, cotton balls, lighters, rubber tying-off cords and stainless-steel spoons

Pre-Drug CSs Drug US

No Euphoria (Withdrawal Eliminated)

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Opiate AddictionAdministration Decreased Blood Pressure Skin Flushed and Warm Meiosis Drying of Secretions Respiratory Depression Antitussive Relaxation Hyperthermia

Withdrawal Increased Blood Pressure Chilliness and Gooseflesh Mydriasis Lacrimination Yawning and Panting Sneezing Restlessness Hypothermia

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Mydriasis33

Some Controlled Experiments Mor-ROOM/Sal-CAGE

Morphine in a distinctive room Saline in the home cage

Mor-CAGE/Sal-ROOM morphine in the home cage saline in a distinctive room

Saline saline in both environments

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Test Day: No DRUG in ROOM

Conditioning Trials

• Acquisition curve• Non-linear• Asymptote

Conditioning Trials

CR

Stre

ngth

asymptote

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Conditioning Occurs Over Trials

(S) Saline in Room

(M-HP) Mor in Room

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Extinction

Trials/Time

Stre

ngth

of C

RAcquisition Extinction

CS&US CS alone

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Extinction of Tolerance

Acquisition Extinction Test 3 Mor in Room 9 Placebo in RoomGroup Extinction (M-P-M)

6 Mor in Room 9 Rest in home CageGroup No Extinction (M-rest-M)

Mor in Room

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Rested animals show a CR (tolerant)

Extinguished animals(tolerance is undone)

Applications: Absence of Pre-Drug CSs42

Heroin Overdose Death 43

Overdose and Death

heroinNew Context

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Conclusions

7. Conditioned responses can be “compensatory”, bringing the organism back to homeostasis

8. Contexts can be conditioned (Best treatment for addiction is the original context).

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