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Ivan Petrovich Pavlov (1849-1936)
 Pavlovian (Classical) conditioning
 Physiologist
 Digestion
 Dogs
 Conditional redirection of reflexes
 Conditional reflexes
Conditional??
 Yes, conditional
 Mistranslated to
conditioned
 For learning at least, this
is where the term
“conditioning” came
from
Terminology
 Unconditional stimulus (US)
 Stimulus that elicits the innate reflex (e.g., food)
 Unconditional response (UR)
 Reflex action that occurs in response to US (e.g., salivation)
 Conditional stimulus (CS)
 Any stimulus that doesn’t originally elicit the UR (e.g.,
buzzer)
 Conditional response (CR)
 The action elicited by the CS (e.g., salivation)
 THIS IS LEARNED
The Basics
 Use behaviours that are already in place – Reflexes
 Associate some new (neutral) stimulus with the
stimulus that evokes the reflex
 How? Present them together!
- CS-US  UR
 Buzzer-food (salivate) - CS-US  (CR) UR
 Buzzer-food (salivate) - CS-US  (CR) UR
 Buzzer-?
- CS  CR
 Buzzer-food (salivate)
The Basics
TIME
Conditional
Stimulus
Unconditional
Stimulus
on
off
on
off
(after enough
pairings)
Conditional
Response
Unconditional
Response
Measuring Conditioning
 Sometimes difficult to measure CR
 e.g., if CS & US close together, CR & UR can overlap
 Buzzer-food-saliva, buzzer-saliva-food?

How long is the separation between the buzzer and the food?
 Intensity
 Does CR intensity increase with experience?
 Test trial (probe trial)
 Give CS alone
Probe (Test) Trials
TIME
Conditional
Stimulus
Unconditional
Stimulus
on
off
on
off
Conditional
Response?
No Unconditional
Response without the
US!
Some notes & examples…
 Awareness is NOT necessary
 Eyeblink
 Conditioned Suppression (Conditioned Emotional
Response)
 Suppression ratios
 Another way of MEASURING conditioning
 Taste Aversion
 Tequila?
S-S or S-R?
 What kind of connection is being made?
US
CS
Response
Rescorla (1973)
 So, how do you get rid of a response that is hard wired
to a stimulus?
 How can you get rid of a reflex?
 Habituation
Results
Group
Phase 1
Habituation L  N
(startle)
Control
LN
(startle)
Phase 2
Test
Noise
Light
(habituate)
Nothing
Light
 Less suppression in Habituation group
 (In other words, more responding)
 Therefore, the connection MUST be S – S
Higher Order Conditioning
 S-S-S?
 CSs and USs can be associated (First-order)
 CSs can be associated with other CSs
 Second-order conditioning
first-order CS
second-order CS
Light (CS2)
tone (CS1)
salivation (CR)
food (US)
Types of Conditioning
 Delay
 Short
 Long
 Trace
 Simultaneous
 Backwards
 Inhibitory
Delay Conditioning
 CS and US overlap
 Short
 Usually the most effective
 Long
 timing
Trace Condition
 From “memory trace”
 Must remember CS
 Other stimuli interfere
CS
GAP
US
Simultaneous conditioning
 Weaker than short delay
 CS can’t signal onset of US
 Not predictive
CS
US
Backwards conditioning
 Much more difficult
 Ignores order
CS
US
Conditioned Inhibition
 CS Up until now, we’ve been talking about CS+
 CS signals the ABSENSE or NON-OCCURRENCE of
US
 Needs to be some expectation of the US for this to
work
CSCS+
US
Factors that affect conditioning
 Contiguity
 Contingency
 Stimulus Features
 Prior Experience
 Number of Pairings
 Intertrial Interval
Contiguity
 Closeness together in time and/or space
 Usually, more learning if greater contiguity between
CS & US
 Type of conditioning may influence this
 e.g., eyeblink vs. taste aversion
 BUT, contiguity is not sufficient!
Group
CS-US
pairings
US alone
CR strength
A
.40
0
Very strong
B
.40
.10
strong
C
.40
.20
Medium
D
.40
.40
weak
Contingency
 If-then situation
 Consistency of pairing CS and US
 Greater contingency, greater learning
 informative
Stimulus Features
 Intensity of stimuli (CS & US)
 Compound Stimuli
 Two+ simple CSs presented at the same time
 Paired with US
 Overshadowing – if one CS is more salient, the other CS
may be ignored
 Nature of Stimuli (relevance or belongingness)
 Loud & noisy water?
Prior experience
 Prior experience with CS and/or US affects
conditioning
 contingency
 Latent inhibition
 Prior experience with an neutral stimulus makes it
harder for it to become a CS later
 Novelty
 Blocking
 Introducing a new CS (CS2) in compound with an
already trained CS (CS1)
 CS2 won’t be learned about
 Sensory preconditioning
 Pair two CSs
 Pair one with a US
 Unpaired CS still elicits CR
Phase 1
(CS1+CS2):
-Light + Tone
-Light + Tone
-Light + Tone
Phase 2
(CS1+US):
-Light + Food
-Light + Food
-Light + Food
Test (CS2?)
-Tone?
(measure
response)
Number of Pairings
 Acquisition curve
asymptote
 Non-linear
CR Strength
 Asymptote
Conditioning Trials
Intertrial Interval
 ITI
 Time between each CS-US pairing (i.e., between trials)
 Generally, around 30 seconds effective
Extinction, Spontaneous Recovery and Reacquisition
Extinction
 Continued pairing of CS with US maintains CR
 CS without US --> Extinction
 Weakening and stopping of CR
 Not forgetting
 A type of conditioning
 Withhold responding
 CS paired with absence of US
Spontaneous Recovery
 After extinction, let time pass
 Present CS again (no US)
 Temporary, small return of CR
 Shows extinction is not forgetting!!
Reacquisition
 Extinguish CR
 Recondition with CS-US pairing
 Fewer trials required
All Together Now!
Strength of CR
Acquisition
CS&US
Extinction
CS alone
Trials/Time
Spontaneous
Reacquisition
Recovery
CS alone
CS&US
How does this all work?
Stimulus Substitution Theory
 Pavlov
 CR and UR produced by same neural region
 Response center
 CS takes on properties of US
 Substitution
US
center
CS
center
Response
center
Sign Tracking
Food
Sign Tracking
But…
 CR should be the same as UR
 e.g. signtracking, autoshaping
 But it’s NOT!!
 Intensity, magnitudes
 Omissions & additions

Different CSs elicit different CRs
 Compensatory responses
Preparatory Response Theory
 Learn responses that prepare organism for US
occurrence
 Sometimes CR same as UR, sometimes different
 Drug Tolerance