Discrimination & Complex
Stimulus Control
Chs12 & 13
Reinforcement-Based
Discrimination
SD
Before
After
Behavior
SD
After
Discriminative Stimulus
D
(S )
• A stimulus in the presence of which a
particular response will be reinforced or
punished
S-delta
D
(S )
• A stimulus in the presence of which a
particular response will not be reinforced or
punished
Reinforcement-Based
Discrimination
SD
Brelandlesss
target
Before
Chicken
has no food
After
Chicken
has food
Behavior
Chicken
pulls the
trigger
After
SD
Breland
Chicken
has no food
Discrimination Training
Procedure
• Reinforcing or punishing a response in the
presence of one stimulus and extinguishing
it or allowing it to recover in the presence of
another stimulus.
Stimulus discrimination
(stimulus control)
• The occurrence of a response more
frequently in the presence of one stimulus
than in the presence of another, usually as a
result of a discrimination training procedure
Differential Reinforcement vs.
Stimulus Discrimination
One Response
Class
Two Response
Classes
One Stimulus
Two Stimuli
No
differentiation
or
discrimination
Response
differentiation
Stimulus
discrimination
Combined
differentiation &
discrimination
Concept training
• Intuition?
– Control by a concept or set of contingencies the
person or organism does not define or describe
• Concept of PERSON is complex
Herrnstein & Loveland
• Concept training procedure with nonverbal
animal
Concept Training
SD
Various
pictures of
people
Before
Behavior
No grain
Pigeon
pecks key
Sdelta
Various
pictures
with no
people
After
Pigeon has
grain
After
Pigeon has
no grain
Concept Training
SD
Various
Picasso
paintings
Before
Behavior
No grain
Pigeon
pecks key
Sdelta
Various
painting by
others
After
Pigeon has
grain
After
Pigeon has
no grain
Complex Stimulus Control
• Conceptual stimulus control
Stimulus class (concept)
• A set of stimuli all of which have some
common physical property
• A stimulus class is the same thing as a
concept
Stimulus generalization
• The behavioral contingencies in the
presence of one stimulus affects the
frequency of the response in the presence of
another stimulus
• E.g. – reinforcement for pecking in
presence of 1 Picasso painting affects
likelihood of pecking in presence of another
Picasso painting (more likely)
Concept Training
• Reinforcing or punishing a response in the
the presence of one stimulus class and
extinguishing it or allowing it to recover in
the presence of another stimulus class
Concept training
Vs.
Conceptual stimulus control
Conceptual stimulus control
• Responding occurs more often in the
presence of one stimulus class and less
often in the presence of another stimulus
class because of concept training
Testing for stimulus
generalization
• Test for stimulus generalization using novel
stimuli
• If respond correctly to novel stimuli, can
say the behavior is under the stimulus
control of concepts.
Stimulus generalization vs.
stimulus discrimination
• Responds in presence of SD but not in the
presence of SD. This is ______________
• Responds at similar rates in presence of SD
and SD. This is __________________
Stimulus Generalization
Number of Responses
60
50
40
30
20
10
0
red
green
blue
yellow
Stimulus Discrimination
45
Number of Responses
40
35
30
25
20
15
10
5
0
red
green
blue
yellow
Stimulus-Generalization Gradient
Number of Key Pecks
350
300
250
200
150
100
50
0
Blue
Yellowgreen
TEST COLORS
Red
Generalization vs. Discrimination
• Amount of generalization is the opposite of
the amount of stimulus discrimination
(stimulus control)
Fading, Errorless Learning,
Imitation
Chapter 13 & 14, Part 2
Fading
• Stimulus dimensions
– The physical properties of stimuli
Stimulus Dimensions
• Stimuli differ from each other
– House vs. car
• Obvious dimensions
– Size, weight, shape, material, etc.
vs.
Stimulus Dimensions
• The more dimensions along which objects
differ, the easier to establish a
discriminative stimulus control
• The fewer dimensions along which objects
differ, the harder it is to establish
discriminative stimulus control
Example
•
•
•
•
Good golf balls (SD) vs. bad golf balls (SD)
This is a discrimination that is difficult
How can the discrimination be established?
The 2 golf balls are similar in so many
dimensions….and differ in only a few
– Roundness, resiliency, hardness of cover
Make stimulus dimensions more
salient, then use fading
•
•
•
•
Color the bad golf ball green
Leave the good golf ball alone
Reinforce picking out good golf balls
Don’t reinforcer picking bad (green) golf
balls
Fading
• Gradually fade out the difference between
good balls and bad balls by reducing the
“green”
Fading procedure
• At first, the SD and the SD differ along at least two
stimulus dimensions (green & white, new & old).
• The difference between the SD and the SD along all
but one dimension is reduced until there is no
difference along the reduced dimensions.
• The the SD and the SD differ along only one
dimension
Errorless Discrimination
Procedure
• The use of a fading procedure to establish a
discrimination, with no errors during
training.
Jimmy
Jimmy
Susan
Jimmy
Susan
Jimmy
Susan
Jimmy
Susan
Jimmy
Susan
Jimmy
Susan
Reinforcement-Based
Discrimination
SD
Jimmy on a
white 
black card
Before
Behavior
Jimmy has
no raisin
Jimmy
picks card
SD
Susan on a
black card
After
Jimmy has
a raisin
After
Jimmy has
no raisin
Stimulus Dimensions
• Lettering
• Shading
• At first, choice of cards was under the
control of the dimension of ________
• Then, after fading, responding was under
the control of the dimension of _______
Techniques of Gradual Change
Procedure
Area of
Application
Purpose
Shaping
Response
differentiation
To bring about a
response not made by
the organism
Reinforcer
Reduction
Type & amount
of reinforcer
To maintain responses
already made or to
establish a particular
pattern of responses
Fading
Stimulus
discrimination
To bring the response
under the control of
stimuli that didn’t exert
control initially
Reinforcer Reduction
• Move from primary to secondary
reinforcers
• Change from 3 pellets to 1 pellet
Imitation
• The form of the behavior of the imitator is
controlled by similar behavior of the model
Imitation Training: Stimulus
Discrimination
SD
Raised arm and
“do this”
Before
Behavior
Marilla has
no food &
praise
Marilla
raises arm
After
Marilla has
food &
praise
SD
After
No arm raised or
no “do this”
Marilla has
no food &
praise
Imitation Training: Differential
Reinforcement
After
Behavior
Before
Marilla has
no food &
praise
Marilla
raises arm
Marilla has
food &
praise
Behavior
After
Marilla
raises arm
Marilla has
no food &
praise
Training Imitation
• Train imitation with a partner
–
–
–
–
Touch nose
Touch toes
Raise hand
Etc……
Generalized Imitation
• Imitation of the response of a model without
previous reinforcement of imitation of that
specific response.