1. Stimulus Control of Behavior

2. Stimulus Control Classical Conditioning: Operant Conditioning:
The CS signals the delivery of the US
Operant Conditioning:
Thorndike's original law of effect implied stimulus control
Stimuli (S) present at the time of the reinforced response come to control the response
S-R
S(R-O)
Not just simple stimuli, the context such as a place also control behavior
Every day examples of stimulus control
Traffic signals control traffic
Classroom context influences student behavior

3. Identification and Measurement of Stimulus Control
Differential Responding and Stimulus Discrimination
How do you know that an instrumental response has come under the control of certain stimuli?
Cartoon
Stimulus control of instrumental behaviour is demonstrated by differential responding in the presence of different stimuli
Reynolds (1961) See Figure 8.1
trained pigeons to respond to white triangle on a red circle
tested then with either a white triangle or a red circle
Some responded more to the white triangle and others to the red circle
Demonstration of individual differences in stimulus control
Stimulus discrimination occurs if an animal responds differently to two or more stimuli
This procedure can be used in any instrumental conditioning to test stimulus discrimination

4. Figure 8.1 – Summary of procedure and results of an experiment by Reynolds (1961).
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.

5. Stimulus generalization
Procedures to measure stimulus control
Generalization occurs when an animal responds in a similar fashion to two or more stimuli
Responding the same amount to two lights
So it is a failure to discriminate between the two stimuli
Stimulus generalization
When testing with a large number of stimuli that vary along a specific characteristic such as color gradients
used to measure amount of stimulus control
Provide an index of how much the physical stimulus has to change for behaviour to change

6. Stimulus Generalization Gradients as Measures of Stimulus Control
Guttman & Kalish (1956)
Pigeons - VI - reinforce responding to a yellow key light (580nm)
test wavelengths were varied from about nm
Gradient of responding:
responding generalized to the range of approx nm
declined sharply to stimuli outside of this range
See Figure 8.2
A flat stimulus generalization gradient indicates the absence of stimulus control.
A sharp or steep stimulus generalization gradient is evidence of strong stimulus control.
The steepness of stimulus generalization gradients provides a precise measure of the degree of stimulus control that a particular stimulus dimension has.

7. Testing stimuli
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.

8. Generalization of Treatment Outcomes Box 8.1
Behavior therapy should generalize to situations outside the therapist’s office
For example bug phobia, Entomophobia
Behavioral therapy to reduce fear of bugs
Treatment such as gradual exposure in the therapist’s office
If this treatment is effective only in the therapist’s office then it is useless
Treatment needs to generalize to other places and situations to be effective
A number of techniques can be used to improve generalization in therapy such as :
a natural environment
across a variety of situations
with a variety of bug examples
with stimuli common to many situations
exposure as part of every day activities
include reinforcement for these every day activities (DRO)

9. Stimulus and Reinforcement Variables
Experimental studies of stimulus control use simple stimuli
white triangle on a red key
Although, even in an operant chamber there are numerous stimuli
a key light has color, shape, size and location
Stimuli in natural environments have complex combinations
Specific sounds
Specific odors
Place context
Social context
Which of these stimuli control behavior is related to
Sensory capacity and orientation
Relative ease of conditioning
Type of reinforcement
Configural cues in compound stimuli

10. Sensory Capacity and Orientation
Sensory systems limit which stimuli can be use as cues to reinforcers
Used to study color vision in dogs (Neitz, 2001)
Dogs were tested in a three alternative force choice discrimination
They viewed three small circular stimulus panels along one wall of the test chamber
Two of the panels were identically illuminated while the third received different illumination
dogs were trained to select the panel that was different from the others

11. Relative Ease of Conditioning Various Stimuli
Environments usually have complex combinations of cues that could function in stimulus control
Walking into a restaurant results in a barrage of sights, sounds, and odors all of which could be cues to getting some food
Some cues in the environment are better stimuli for predicting response - outcome combinations because of
Stimulus salience such as intensity of a stimulus
belongingness i.e. odor for food
Overshadowing: Stimuli that get more attention and work as better cues can overshadow other cues in that situation
Table 8.1 experimental design for overshadowing

12. Overshadowing experiment using Pavlovian fear conditioning
Weak/Strong
Weak
Overshadowing experiment using Pavlovian fear conditioning
Potentiation and Overshadowing in Pavlovian Fear Conditioning (Urcelay and Miller 2009)
Overshadowing group:
(CS1)Weak clicker sound with (CS2) Strong 3000Hz tone paired with footshock
(CS2) was 5 dB louder
Control group:
Weak clicker sound paired with footshock
Testing for both groups is clicker sound only
overshadowing group has less fear response compared to the control group
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.

13. Type of Reinforcement
Instrumental outcomes can be appetitive or aversive
Getting food is reinforcing
Avoiding shock is reinforcing
Pigeons: Trained with compound tone/light stimulus
One group received appetitive food reinforcer
other group could avoid footshock, a negative reinforcer
Tested with light only and tone only
Visual cues better for appetitive situations
Auditory Cues better for aversive situations
See Figure 8.4
Behavioural ecology of species and the behaviour systems activated are important factors
In this case pigeons foraging vs defensive behavior

14. The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.

15. Stimulus elements versus configural cues
Stimulus-element approach:
control over behaviour by distinct and separate elements of a stimulus compound such as white triangle on red
not all stimulus compounds are processed as distinct stimulus elements
Process a stimulus compound as a unique integral whole
Configural-cue approach:
configural information about the entire compound enters into an association with the US

16. Configural cues and overshadowing
Is Overshadowing due to differential associations being acquired by the elements, or is it due to the association being acquired by the configural compound “aB” ?
Does a stimulus compound like aB consist of two separate elements "a" and B or is it a new entity aB that cannot be decomposed into separate elements?
Configural-cue approach explains overshadowing in terms of generalization decrement from training to test
In control group, training stimulus "a" is identical to test stimulus "a"
In overshadowing group, training stimulus aB is very different from the test stimulus "a“

17. Importance of Configural-Cue Approach
Compound Stimuli can acquire control over behaviour
By each of the stimulus elements
as well as by stimulus configurations; the “configural cues”
In some situations, stimulus elements predominate while in other situations control by configural features is dominant.
There is debate over and current research on which conditions produce configural cue conditioning
The configural-cue approach also helps us to be aware of generalization decrement as an alternative explanation of a variety of research findings involving stimulus compounds.