Stimulus Control of Behavior

1
Stimulus Control of Behavior

• Stimulus control of operant behavior
• Context drives appropriate behavior
• Depending on where you are, the situation you are
  in , etc., certain behaviors are acceptable
  these same behaviors may be inappropriate in
  different contexts/situations
• Behavior must adjust to the environment

2
Stimulus Control of Behavior

• Stimulus discrimination and generalization
• How organisms identify and distinguish different
  stimuli considered one of the most important
  concepts in psychology
• No situation repeats itself exactly, so a degree
  of generalization is necessary
• However, also critical to distinguish various
  stimuli
• Stimulus discrimination
• Differential responding to two or more stimuli
• Stimulus generalization
• Similar responding to two or more stimuli

3
Stimulus Control of Behavior

• How can we measure the degree of stimulus control
  in a given situation?

4
Basic Procedure

• Generalization test A variety of stimuli from
  the same stimulus continuum are shown, one at a
  time, under extinction conditions.

5
Basic Procedure
Positive Stimulus
Generalization Test
6
Basic Procedure
Stimulus Color
7
Generalization Gradient

• A generalization gradient shows the relationship
  between the probability of response and stimulus
  value.

8
Gradients and Learning

• The accuracy of responding improves as the
  individual becomes more experienced with the
  stimulus dimension.

9
Experience Changes the Gradient
Novice
Expert
S
S
10
Stimulus Control of Behavior

• How can we measure the degree of stimulus control
  in a given situation?
• Stimulus generalization gradients
• Guttman Kalish (1956)
• Pigeon pecking reinforced to 580nm color (this
  is S) no S- training conducted
• Substantial responding to stimuli never
  associated with reinforcement
• Generalization to 570 590 evidence of greater
  discrimination (decreased responding) as
  wavelengths became increasingly different from
  original stimulus

11
Gradient Shape

• Steep vs. flat gradients
• Steepness of stimulus generalization gradient
  provides a measure of the degree of stimulus
  control
• Steep gradient differential responding (see
  FIGURE to right)
• Evidence that the stimulus feature that is varied
  controls behavior
• Flat gradient lack of differential responding
• Evidence that the stimulus feature that is varied
  does NOT control behavior

12
Factors in Stimulus Control Features

• What determines which features of stimuli gain
  control over behavior?
• Sensory capacity
• Ease of