PSYC 3450 Chapter Notes - Chapter 10: Discrimination Learning, Stimulus Control, Prefrontal Cortex
28 Apr 2018
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Chapter 10: Stimulus Control of Behavior
Stimulus control of behavior usually occurs in the form of two processes
categorized as generalization and discrimination.
Stimulus generalization: An individual may respond in the same way to
similar stimuli
Stimulus discrimination: Individuals may also learn to respond in
different ways to different stimuli; the process of responding to some
stimuli but not others is called discrimination learning
A) Stimulus Generalization Process
-Some Americans dislike Arab Moslems. Stimulus generalization may be
responsible for their strong, negatively conditioned emotional response
-Stimulus generalization occurs frequently in the real World. Sometimes
stimulus generalization is undesirable, as when some Americans choose
to dislike all Arab Moslems.
-Stimulus generalization is often adaptive. For example, if a parent
reads a book to a child and the child enjoys it, a positive emotional
experience is conditioned to the book.
Generalization Process
Generalization gradient: Is a visual representation of the strength
produced by stimuli of varying degrees of similarity to the stimulus
present during training; these gradients Show the level of generalization
that occurs to any given stimulus similar to the one present during
conditioning. A steep generalization gradient indicates that people or
animals respond very little to stimuli that are not very similar to the
training stimulus, while a flat generalization gradient Shows that
response occurs even to stimuli quiet unlike the conditioning stimulus
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Stimulus Response Gradient: Gradient of responding depends on how
similar the stimuli are in the training stimulus
When stimuli are similar, the peek is steep Strong stimulus control-
they are able to discriminate between stimuli
When stimuli are not similar the peek is flat Poor stimulus control-
they are not able to discriminate between stimuli
Excitatory-Conditioning Generalization Gradients
-Pigeons-Guttman and Kalish noted that the level of response declined
as the difference between training and test stimuli increased.
-Hoveland paired a tone (S+) with an electric shock and then
investigated the generalization of the galvanic skin response. Hoveland
reported that less response occurred as the test and conditioning tones
became more dissimilar.
-Guttman and Kalish performed the classic excitatory generalization
experiment.
They trained different groups of pigeons to peck a stimulus key that
varied in its wavelength.
After training, each group was given test stimuli, including wavelengths
that were higher and lower than the original stimulus. Response levels
were measured for each stimulus.
Guttman and Kalish consistently observed symmetrical generalization
gradients with the highest level of responding occurring at the original
training stimulus.
Inhibitory-Conditioning Gneralization Gradients
Weisman and Palmer studied this. Pigeons were first trained to peck a
green disk(S+) to receive food reinforcement. When a vertical line (S-)
presented, the pigeons were not reinforced for key pecking. Inbibitory
generalization test were conducted with other lines that differed from
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the original vertical line by various degrees of arc. The results showed
the greater the difference between the original vertical line and the test
line, the less was key pecking inhibited.
The Nature of the Generalization Process: The Lashley-Wade theory of
stimulus generalization explains why stimulus generalization occurs on
some occasions but not others.
Animals and people respond to stimuli that differ from the training
stimulus because they are unable to distinguish between the
generalization test stimulus and the conditioning stimulus. Thus, an
inability to discriminate between the training and test stimuli is
responsible for stimulus generelization. If people could differentiate
between the conditioning stimulus and other stimuli, Lashley and
Wade’s ie suggests they ould ot “ho a geealized espose to
other stimuli. Therefore, according to Lashley and Wade, stimulus
generalization represents the failure to discriminate, discrimination
prevents stimulus generalization, and a failure to discriminate leads to
generalization.
Several lines of evidence support this theory. First, generalization to
stimuli even dissimilar to the training stimulus occurs when
nondifferential reinforcement training is used.
When nondifferential reinforcement is used, the conditioning stimulus
is present during the entire training session. Thus, the only stimulus the
subject experiences is the excitatory stimulus (S+) The Lashley Wade
view suggests that without experience with stimuli other than S+, the
subject will genralize to all stimuli.
The Jenkins and Harrison In their study, control group animals
received nondifferential training, with the 1,000 Hz tone present during
the entire conditioning session. Following training, each subject was
exposed to seven tones ranging from 300 to 3,500 Hz and to a nontone
presentation.
The pigeons responded equally to all tones.
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Document Summary
Stimulus control of behavior usually occurs in the form of two processes categorized as generalization and discrimination. Stimulus generalization: an individual may respond in the same way to similar stimuli. Stimulus discrimination: individuals may also learn to respond in different ways to different stimuli; the process of responding to some stimuli but not others is called discrimination learning: stimulus generalization process. Stimulus generalization may be responsible for their strong, negatively conditioned emotional response. Stimulus generalization occurs frequently in the real world. Sometimes stimulus generalization is undesirable, as when some americans choose to dislike all arab moslems. For example, if a parent reads a book to a child and the child enjoys it, a positive emotional experience is conditioned to the book. Stimulus response gradient: gradient of responding depends on how similar the stimuli are in the training stimulus. When stimuli are similar, the peek is steep strong stimulus control- they are able to discriminate between stimuli.
