Classical Conditioning I
Classical Conditioning
Classical or Pavlovian conditioning
Unconditioned Stimulus (US)
Automatically elicits a response (reflex)
Unconditioned Response (UR)
Food, Water, Sex, Pain, etc.
Conditioned Stimulus (CS)
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
Autoshaping
When there is a contingency between a tangible CS
and a pleasurable US, the CR is directed at the CS.
Sign tracking (cf. Goal tracking)
Pigeons
key light CS  food US
response: peck key light CS
Rats
insert lever CS  food US
response: lick lever
ball bearing CS  food US
response: handle ball bearing
Autoshaping Movies
Long-box autshaping
Omission training
Fear Conditioning
(tone)
Notation:
Tone +
Or
ToneShock
(shock)
After one or two pairings…
(CS)
(CR’s)
Blood pressure
Heart Rate
Stress Hormones
Freezing
Conditioned Suppression
Suppression Ratio
a = responses during the CS
b = responses prior to the CS
a
a+b
On first Tone-Shock trial:
a = 30; b = 30. 30/(30+30) = 0.50
After 10 Tone-Shock trials: a = 3; b = 20.
3/(3+20) = 0.13
Fear-Potentiated Startle (Davis)
Train:
Test:
Tone
Shock
Startle Stimulus (Loud Noise) Alone
Vs.
Startle Stimulus + Tone
DV: How high do they jump?
Startle Amplitude
Startle Amplitude
120
100
80
60
40
20
0
Tone
No Tone
vs.
Feedback
Feedforward
Some properties of classical
conditioning
Discrimination
1.2
CS+
CS-
Response Strength
1
0.8
0.6
0.4
0.2
0
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
Generalization
Trained
frequency
CR’s
Tone 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
UCS = Water (note the closed beak)
UCS = Food (note the open beak)
From Jenkins & Moore, 1973
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
Begin
cooling
response
Enter
sauna
Body
temp
98.6
time
Vasodilation
=
sweating
Opponent Process Theory of Motivation
Siegel
Ave. C
Buddy Jimmy
Favorite belt
Etc.
heroin
Euphoria
Big departure
from
homeostasis
Siegel
Ave. C
Buddy Jimmy
Favorite belt
Etc.
heroin
Euphoria
Smaller departure
from homeostasis
Siegel
Ave. C
Buddy Jimmy
Favorite belt
Etc.
heroin
Euphoria
Even smaller departure from
homeostasis
Siegel
Ave. C
Buddy Jimmy
Favorite belt
Etc.
heroin
Euphoria
Departure from
homeostasis
Siegel
New Context
heroin
Euphoria
Departure from
homeostasis
Siegel
CS
US
Conc. Of
drug in
Brain
Time since admin.
Montaigne:
“My appetite comes to me while
eating”
-Of Vanity (1500-ish)