Transcript 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 S d )
Signals that reinforcement will not be available, even if the response occurs (S
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Discrimination
Animals learn to demonstrate differential patterns to responding to different stimulus conditions
Response Pattern
Resp/Min
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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
% CR to tone CS+ 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
CS+ Response Strength CS-
Peak Shift Phenomenon
CS+ Response Strength 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 G Peck Reinforce
V. Natural Concepts
Some processes
– Oddity responding R R G Reinforce Peck
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