Classical Conditioning I. Classical Conditioning

Classical Conditioning I

Classical Conditioning

Classical or Pavlovian conditioning

Conditioned Stimulus (CS)

Unconditioned Stimulus (US)

Automatically elicits a response (reflex)Unconditioned Response (UR)

Food, Water, Sex, Pain, etc.

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

Some response systems that participate in classical conditioning

• Endorphins and analgesia

• Sexual arousal

• Immune suppression/enhancement

• Fear

AutoshapingWhen there is a contingency between a tangible CS

and a pleasurable US, the CR is directed at the CS. Sign tracking (cf. Goal tracking)

Pigeonsresponse: peck key light CS

Rats

key light CS food US

response: handle ball bearingball bearing CS food US

insert lever CS food USresponse: lick lever

Autoshaping Movies

Long-box autshaping

Omission training

Fear Conditioning

(shock)

(tone)

Notation:

Tone +

Or

ToneShock

After one or two pairings…

(CS)

Blood pressure

Heart Rate

Stress Hormones

Freezing

(CR’s)

Conditioned Suppression

Suppression Ratio

a = responses during the CS

b = responses prior to the CS

aa + b

After 10 Tone-Shock trials: a = 3; b = 20. 3/(3+20) = 0.13

On first Tone-Shock trial: a = 30; b = 30. 30/(30+30) = 0.50

Fear-Potentiated Startle (Davis)

Tone ShockTrain:

Test: Startle Stimulus (Loud Noise) Alone

Vs.

Startle Stimulus + Tone

DV: How high do they jump?

Startle Amplitude

0

20

40

60

80

100

120

Tone No Tone

Sta

rtle

Am

plit

ud

e

Feedback

vs. Feed-forward

Some properties of classical conditioning

Discrimination

0

0.2

0.4

0.6

0.8

1

1.2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Trials

Re

sp

on

se

Str

en

gth

CS+

CS-

Generalization

CR’s

Tone frequency

Trained frequency

What determines the form of the CR?

Stimulus Substitution

Behavior Systems

Opponent Processes

Stimulus Substitution (the CS takes the place of the US)

• Pavlov: UR = Salivation, CR = Salivation

• Cocaine: UR = Activity, CR = Activity

• Cyclophosamide: UR & CR = immune suppression.

• Autoshaping: CR for water = Closed beak, CR for grain = Open beak

Form of the CR in Sign Tracking

From Jenkins & Moore, 1973

UCS = Water (note the closed beak)

UCS = Food (note the open beak)

video

However…

• Fear conditioning: CR = freezing, UR = activity

• CS can determine form of CR

Form of CR depends on CS

However…

• Fear conditioning: CR = freezing, UR = activity

• CS can determine form of CR

• Interval between CS and US matters– Long delay: General search CR– Short delay: Focal search CR

Behavior Systems Theory

• Holland (1984); Timberlake & Silva; Akins

The CS and US engage the same “behavior system” – e.g., appetitive, sexual, defensive.

The form of the CR depends on the length of the delay between CS and US.

Overt CR is flexible – depends on situation

Another View: Opponent Process Theory

Conditioning helps maintain homeostasis

US’s divert organism away from homeostasis

time

Body temp

Enter sauna

Begin cooling response

=Vasodilation

sweating

98.6

Opponent Process Theory of Motivation

Siegel

heroin

Ave. C

Buddy Jimmy

Favorite belt

Etc. Euphoria

Big departure from homeostasis

Siegel

heroin

Ave. C

Buddy Jimmy

Favorite belt

Etc. Euphoria

Smaller departure from homeostasis

Siegel

heroin

Ave. C

Buddy Jimmy

Favorite belt

Etc. Euphoria

Even smaller departure from homeostasis

Siegel

heroin

Ave. C

Buddy Jimmy

Favorite belt

Etc. Euphoria

Departure from homeostasis

Siegel

heroin

New Context

Euphoria

Departure from homeostasis

Siegel

Time since admin.

Conc. Of drug in Brain

CS US

Montaigne:

“My appetite comes to me while eating”

-Of Vanity (1500-ish)