Download Stimulus Control of Operant Behavior

Stimulus Control of Operant
Behavior
Overview of
stimulus
control of
operant
behavior
Discrimination
Generalization
Generalization Gradients
Peak Shift
Concepts
I. Operant Discrimination

Known as the study of discrimination
learning or stimulus control
 Discriminative stimulus - Signals that
reinforcement will be forthcoming if the
response occurs (S+ or Sd)
 Signals that reinforcement will not be
available, even if the response occurs (Sv)
Discrimination

Animals learn to
demonstrate
differential patterns to
responding to
different stimulus
conditions
Response Pattern

Resp/Min

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S+ or
Add text, graphic
photo at left
S-
II. Generalization

Similar patterns of responding to similar
stimulus conditions
 The opposing qualities of discrimination
III. Generalization Gradients
Early in discrimination training
CS+
Generalization Gradients
Later in discrimination training
CS+
Generalization Gradients

Excitatory Pattern of Responding
CS+
Generalization Gradients

Inhibitory Pattern of Responding
% CR
CS-
Generalization Gradients

Excitatory of Responding
CS+
% CR
to
tone
1 KHz
Generalization Gradients

Inhibitory Pattern of Responding
% CR
to
tone
CS-
570 nm
Predictiveness and
Redundancy


Conditioning will
occur to the stimulus
which most predictive
An especially salient
CS may overshadow
the other stimuli
Overshadowing

Depends upon nature of the environment,
the past history of the animal and similar
issues
 Highly salient stimulus qualities often
overshadow other stimuli
 Specific features of the stimulus may be
attended to
Attention Training

Relevance must be learned
 Behavior must be demonstrated
 Transfer of training studies
– Paying attention is a separate part of the
discrimination learning
Attention Training

Dimensional shift learning paradigm
– Intradimensional shift - Train to CS+
quality, shift to different type of same
dimension (e.g. shift from red to blue for
CS+)
– Extradimensional shift - Train to CS+
quality, shift to different dimension (e.g.
from color to shape for CS+)
Attention Training

Extradimensional shift is more difficult
IV. Process of
Generalization

Extinction builds to CS+ and inhibition
builds to CS Early work of Spence 1936, 1937; and Hull
1943, 1952
 According to Spence’s theory, excitation
and inhibition add together in an algebraic
fashion
Peak Shift Phenomenon
Response
Strength
CS+
CS-
Peak Shift Phenomenon
Response
Strength
CS+
CS-
V. Natural Concepts

Concepts are related by unifying or
common properties
 Abstract concepts
– “Same” or “different”
– Often not limited to specific concrete
qualities
V. Natural Concepts

Some processes
– Matching to sample
R
R
Peck
Reinforce
G
V. Natural Concepts

Some processes
– Oddity responding
R
Peck
R
G
Reinforce
V. Natural Concepts

Wittgenstein in 1953
 It is not clear what specific features or
qualities are being responded to
 What is a dog?
 What are the qualities of “dogginess?”
V. Natural Concepts

Herrnstein work in the 1980s
 Demonstrated discrimination of natural
objects by pigeons
 Sort stimuli by water, trees or a particular
person
 Organisms as simple as pigeons can
reliably demonstrate this discrimination
Learning Theory and
Memory

Are there behavioral ways to describe
remembering and knowing?
 Some procedures include delayed
matching to sample
– Matching accuracy decreases as a function
of time
Matching Accuracy Over
Time
100
Percentage
Correct
50
Seconds
Matching Accuracy Over
Time and Sample Duration
100
Percentage
Correct
14 sec sample
8 sec sample
4 sec sample
50
Seconds
Working Memory

Memory is an active process
– Susceptible to interference
 Retroactive
interference - interfering stimulus
comes after the stimulus to be remembered
 Proactive interference - interfering stimulus
comes before the stimulus to be remembered
Working Memory

Symbolic matching works as effectively as
direct stimulus matching
– For example, red to vertical lines is
remembered as well as red to red
– Directed forgetting - stimulus learning is
followed by a signal that the stimulus is to
be remembered or not
– It appears memory is an active process
Spatial Memory and
Cognitive Maps

Memory for places
– Maze learning studies
– Little indication of decay over time
– Tends to be accounted for by a cognitive
representation of space