PS261 Chapter Notes - Chapter 8: Psychoactive Drug, Equivalence Class, Stimulus Control
Chapter 8 − Stimulus Control of Behaviour
8.1 − Introduction
- Research on the associative structure of instrumental conditioning deals with how
stimuli come to determine whether or not the instrumental response is performed
- Studying is under the strong control of school-related stimuli
o The stimuli of semester breaks are very different from the stimuli students
experience when classes are in session
▪ Semester breaks do not engender effective studying behaviour
- Failure of appropriate stimulus control is considered abnormal
o Ex. talking in absence of an audience is strange and evidence of psychopathology
8.2 − Identification & Measurement of Stimulus Control
8.2.a
−
Stimulus Discrimination & Differential Responding
- The stimulus control of instrumental behaviour is demonstrated by variations in
responding related to variations in stimuli
o Differential responding to two stimuli indicates stimulus discrimination
- Stimulus discrimination and stimulus control are two ways of considering the same
phenomenon, cannot have one without the other
8.2.b
−
Stimulus Generalization Gradients as Measures of Stimulus Control
- An organism is said to show stimulus generalization if it responds in a similar fashion to
two or more stimuli
o Stimulus Generalization Gradient: gradient of responding as a function of how
similar each test stimulus was to the original training stimulus
▪ A steep generalization gradient indicates strong control of behaviour by
the stimulus dimension that is tested
▪ A flat generalization gradient indicates weak/nonexistent control of behaviour
8.3 − Stimulus & Response Factors in Stimulus Control
- Stimulus and reinforcement variables determine which of the numerous features of a
stimulus situation gains control over the instrumental behaviour
8.3.a
−
Sensory Capacity & Orientation
- Sensory Capacity and Orientation: most important variables that determine whether a
particular stimulus feature controls responding
o Determine which stimuli are included in an organism's sensory world
- Because sensory capacity sets a limit on what stimuli can control behaviour, studies of stimulus
control are often used to determine what an organism is able to perceive
8.3.b
−
Relative Ease of Conditioning Various Stimuli
- Stimulus control also depends on the presence of other cues in the situation
- Overshadowing: how strongly organisms learn about one stimulus depends on how easily
other cues in the situations can become conditioned
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o Competition among stimuli for access to the processes of learning
o In overshadowing experiment:
▪ One stimulus is low intensity (a) and the other is high intensity (B)
• Both presented together (aB) as compound cue and paired with
reinforcement
▪ For control group, only (a) is presented during conditioning
▪ Tests show less responding to (a) in overshadowing group than control group
• Presence of (B) during conditioning disrupts control of behaviour by
weaker stimulus (a)
- If two stimuli are presented at same time:
o Presence of the more easily-trained stimulus may hinder learning about the other one
8.3.c
−
Type of Reinforcement
- Certain types of stimuli are more likely to gain control over behaviour in appetitive than
in aversive situations
o Visual control predominates when the CS acquires positive/appetitive properties
o Auditory control predominates when the CS acquires negative/aversive properties
- Food eaten by pigeons and rats is more likely to be identified by visual cues than auditory
o Activation of the feeding system is accompanied by increased attention to visual
rather than auditory stimuli
- A signal for an aversive outcome activates defensive behaviour system
o Responding to auditory cues is particularly adaptive
8.3.e
−
Stimulus Elements vs. Configural Cues in Compound Stimuli
- Stimulus Element Approach:
o Treating various components of a complex stimulus as distinct and separate elements
▪ Ex. visual vs. auditory cues
- Configural Cue Approach:
o Stimulus elements are important not because of their individuality, but because of how
they contribute to the entire configuration of stimulation provided by the compound
▪ Ex. sound of an entire orchestra is very different from sound of any
individual instrument − some of which are difficult to identify when entire
orchestra is playing
• We primarily hear the configuration of the sounds created by all the
instruments playing
o Overshadowing reflects different degrees of generalization decrement (reduction)
from training to testing
8.4 − Learning Factors in Stimulus Control
- Whether or not certain stimuli come to control behaviour depends on what the individual
has learned about those stimuli, not just whether the stimuli can be detected
o That experience with stimuli determines the extent to which these stimuli control
the behaviour originated in efforts to explain stimulus generalization
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Document Summary
Research on the associative structure of instrumental conditioning deals with how stimuli come to determine whether or not the instrumental response is performed. Studying is under the strong control of school-related stimuli: the stimuli of semester breaks are very different from the stimuli students experience when classes are in session, semester breaks do not engender effective studying behaviour. Failure of appropriate stimulus control is considered abnormal: ex. talking in absence of an audience is strange and evidence of psychopathology. 8. 2 (cid:498)identification & measurement of stimulus control(cid:499) The stimulus control of instrumental behaviour is demonstrated by variations in responding related to variations in stimuli: differential responding to two stimuli indicates stimulus discrimination. Stimulus discrimination and stimulus control are two ways of considering the same phenomenon, cannot have one without the other. 8. 2. b (cid:498)stimulus generalization gradients as measures of stimulus control(cid:499) 8. 3 (cid:498)stimulus & response factors in stimulus control(cid:499) stimulus situation gains control over the instrumental behaviour.
