Chapter 8: Stimulus Control of Behaviour

Question 1

S+

Answer 1

Response and outcome

Question 2

S-

Answer 2

response -> no outcome

Question 3

Stimulus control

Answer 3

the degree to which an organism produces (or withholds) a response in the presence of a stimulus vs. its absence (or presence of other stimuli)

Question 4

How to measure stimulus control

Answer 4

How do we “ask” animals (or human infants) if
two stimuli are different from one another?
– Differential responding
• Remember the habituation to visual patterns in infants?
– Stimulus discrimination: differential responding in the presence of two or more stimuli

Question 5

Reynolds (1961)

– “What is the pigeon paying attention to?”

Answer 5

compound stimulis

peck differently
both pigeons respond differently
at no point were these pigeons explicitly trained to peck the site triangle or red circle

results here are purely by chance, but overshadowing could occur (classical conditioning) one element is more salient and thus can control behaviour to a stronger degree. Overshadowing seen in stimulus control in operant conditioning

less likely to learn about the less salient stimulus

Different stimulus elements controlled responding of different birds

Question 6

Compound Stimuli & Overshadowing

Answer 6

• Some compounds show learning decrements for particular less-salient elements

Question 7

Stimulus generalization

Answer 7

• Failure to discriminate between two similar
stimuli
– i.e., Baby Albert generalized his response
– Baby Albert did not discriminate between a white rat and a rabbit, a white mask, or a furry blanket

opp of stimulus discrimination

phobias develop like this

Question 8

Stimulus generalization gradient

Guttman & Kalish (1956)

Answer 8

Pigeons trained to peck a
certain wavelength of light
– Food reward

“Probe” test with all different
wavelengths
– no reward

Gradient of responding is a
function of how similar each
test stimulus is to the training
stimulus
(Trained CS = light 530 nm, but Pigeons show CR (key pecking) to similar wavelengths of light)

most responding (the peak) when the colour is just right, also responding to similar colours = generalized responding to similar colours

• • The steeper the gradient, the more
  stimulus control

What if there was no stimulus control?
• Then the animals would respond non-differentially

Question 9

Sensory capacity

Answer 9

Stimulus control can ask questions about
what animals perceive

– Can an animal see colors?
• Train to discriminate between colours

– What is an animal’s sensory range?
• Train to discriminate between presence and absence of acoustic (or other) cue

Question 10

Sensory capacity example
Japanese quail and European starlings trained
to discriminate between two different visual stimuli

Answer 10

people are trichromatic
birds are tetra
birds can see in UV spectrum

ask bird can you see the diff between these two lights if one has food and the other does not? Diff outcomes for responses made

just as good in UV and non UV light trials
therefore they can see UV light!

Question 11

Not All Stimuli Are Discriminated Equally

Answer 11

• Some stimuli are more easily used as
discriminative stimuli than others
• Training songbirds to discriminate natural
stimuli goes more quickly than training synthetic stimuli

Question 12

Degree of stimulus control also depends

on the type of reinforcement used. How?

Answer 12

Some stimuli work better when contingent
with positive reinforcement, others with
negative reinforcement
• Foree and LoLordo (1973) tested this idea
in pigeons

pigeons like visual cues associated with foods!

some work better with appetitive reinforcement, and others with aversive reinforcement

Question 13

Foree & LoLordo (1973)

Type of Reinforcement

Answer 13

Training:
• Group 1
– L/T … press pedal … food 
• Group 2
– L/T … press pedal … avoid shock

Group two more likely to press when the T is presented, than when the light is on

Group 1 respond just as much to the L as to the L and the T, and never respond when just the T is on

both outcomes are good, but the type of outcome drastically changes their responding

summary:
Belongingness & behavioural systems
– Food activated feeding system
• Visual cues ‘go with’ food 
– Shock activated defensive system
• Auditory cues ‘go with’ predators

Question 14

Overshadowing

Answer 14

• Stimulus salience • Both ‘belongingness’ and intensity

Question 15

Stimulus Discrimination Training

Answer 15

• Pavlov believed generalization was transfer of learning
• More recently accepted as lack of training (the more training you have, the better you are at discriminating between stimuli Cs+ or CS- or with S+ and S-).

Can have discrimination training in both
classical and instrumental conditioning
– Classical Conditioning: CS+ or CS-
– Instrumental Conditioning: S+ or S-
• Stimuli explicitly associated with other
stimuli or outcomes

first generalization, then discrimination

Question 16

Errorless Discrimination Training

Answer 16

Faster, fewer errors by “fading in” S- over trials
early on S+ is more salient, early on more likely to respond to something obvious.

technique can be used in teaching children
builds confidence in children
higher reinforcement that there is less requirement for errors in learning

Question 17

Training and Stimulus Control

Answer 17

Use generalization gradient to determine
degree of stimulus control

Need to determine the feature(s) of the
discrimination procedure that controls the
gradient

Question 18

Jenkins & Harrison, 1962

Answer 18

• Stimulus control increased by discrimination
training
• If S+ and S- differ along a single stimulus dimension, then more control stimulus control can be gained

single modality
pitch of tones is diff
if a S- is trained, you see more stimulus control than the group that never gets trained with a S-

Question 19

Spence’s Theory of Peak Shift

Answer 19

• Excitation develops around the S+
• Inhibition develops around the S-
• Peak-shift was the net effect of these two generalization gradients

Question 20

Stimulus Generalization and Prejudice

Answer 20

Lack of Discrimination Training
• Miller (1948):
“Displacement” caused by discrimination + generalization
• “Mere Exposure Effect”

Question 21

Phobias and other Anxiety Disorders

Answer 21

•Problems of stimulus generalization
•Fear-inducing scenario;
generalized anxiety to similar (but innocuous) situations

Question 22

peak shift

Answer 22

The ‘peak shift’ effect is basically to do with how, when we’ve (I say we, most of the work is from non-human animals, but it is noted in humans too) learnt to be rewarded for one thing and not for a similar thing, we will respond more so something more different to the non-rewarded thing.

Question 23

Pigeon Art Appreciation

Answer 23

• Watanabe et al. (1995)
• Trained pigeons to discriminate between Monet and Picasso
• Achieved high degree of accuracy

• Pigeons generalized to other artists of the
same style (Impressionist or Cubist)

Question 24

Pigeon Cancer Diagnosis

Answer 24

• Levenson et al. (2016)
• Trained pigeons to discriminate between mammograms with and without masses
• Achieved high degree of accuracy except on images that doctors struggle to diagnose

Question 25

Categorization

Answer 25

• Discrimination of stimuli and transfer to
novel stimuli is indicative of categorization
• …or even concept learning

Question 26

Concepts

Answer 26

• Abstract relations between categories, such

as “bigger”, “faster”, or simply “same as”

Question 27

Stimulus Equivalence

Answer 27

• Explicit generalization training

* e.g., teaching relationships

Question 28

Stimulus Equivalence Classes

Answer 28

Exhibit three properties:
• Reflexivity: A = A, B = B
• Symmetry: if A = B, then B = A
• Transitivity: if A = B and B = C, then A = C
• Importance of stimulus equivalence in language learning

Question 29

Contextual Cues

Answer 29

• Not all discriminative stimuli are
discrete or explicitly-presented 
• e.g., training animal in one box and
testing in another 
• Think of ‘context-dependent learning’

Question 30

Interoceptive Cues

Answer 30

• Stimuli that are internal to the
animal also control behaviour 
• e.g., body states (hunger, arousal),
internal sensation (drug process),
or cognition (‘sense’ of time) 
• Think of ‘state-dependent learning’

Question 31

Conditional Relations

Answer 31

• Discriminative stimuli set the occasion for responding

* Remember S(R-O) learning: the response-outcome relationship is conditional upon the correct stimulus

Question 32

Modulation

Answer 32

• A cue that signals when a CS or response will end with a particular outcome modulates or facilitates the relationship (and thus responses)

Question 33

Stimulus-Element Approach

Answer 33

• So far our focus has been on the individual
elements of compounds (light, tone) rather
than holistic compounds (light+tone)

Question 34

Configural-Cue Approach

Answer 34

• Gestalt compounds
• Overshadowing results from different generalization decrements for elements
• ‘Pigeon art appreciation’ difficult to explain from individual elements

Question 35

Positive/Negative Patterning

Answer 35

• Explicit compound-cue training

Question 36

Sequence Discrimination

Answer 36

• Chaining and other complex stimulus/behaviour sequences

* Individual steps serve as S+ for next response

Question 37

“Pigeons Rank-Order Responses to Temporally Sequential Stimuli”

Answer 37

• Same stimuli: discriminative component based on time/order
• S+ : red-green-blue
• S- : any other order
• More responses during reinforced order and to stimuli closer to blue

Question 38

Stimulus Control in Daily Life

Answer 38

Studying, Sleeping • Avoid contexts (SD) that cue non-target behaviours