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STIMULUS CONTROL OF BEHAVIOR. Chapter 10. Other Discrimination Phenomenon. 2.
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STIMULUS CONTROL OF BEHAVIOR Chapter 10
Other Discrimination Phenomenon 2 “James makes a significant efforts in supplying love, care or attention to Jamie, and she enjoys and reacts positively to his efforts. However, at a later date, these practices diminished to some degree. Jamie is now more upset than if he had never made an effort.”
Other Discrimination Phenomenon 3 • Behavioral contrast • An increasing response a richer schedule because of the existence of a leaner schedule. (Positive Contrast) • A decreased response to leaner schedule because of the existence of a richer schedule. (Negative Contrast)
Yikes 4 • The behavioral contrast phenomenon points to one problem with discrimination learning: It can have negative consequences • A decrease in a negative behavior in one setting can lead to its increase in another setting. • e.g., “covert sensitization” in the therapists office and pedophilia
Other Types of Contrast 5 • Local contrast • A change in responding that occurs following a change in reinforcement contingency. The change in behavior fades with extended training. Short-lived emotional response. • Anticipated/Sustained contrast • A change in responding due to the anticipated future change in the reinforcement contingency.
Anticipatory Contrast 6 • 1. VI-60, 2. VI-30, 3. VI-60 • Compare #1 and #3 • VI-30 might increase the first VI-60 (#1) more than the last VI-60 (#3) -- a looking forward effect Responses 100 125 200 VI-60 VI-30 VI-60
The Aversive Character of S- 7 • Terrace (1964) suggested that behavioral contrast is responsible for the heightened response seen with discrimination training. • Argued that exposure to the S- an aversive event and that the frustration produced during S- periods increased the intensity of the response to other stimuli. • The effect of drugs that eliminate frustration induced behavior supports Terrace’s view.
Errorless discrimination learning 8 • A training procedure in which the gradual introduction of S- leads to fewer, if any, errors to S-
Features of errorless learning 9 • Hardly any mistakes • The peak shift does not appear • Drugs that inhibit frustration induced behaviors have no effect on responding to the S- • However, this produces poorer discrimination of S+ when the situation is changed
The Transposition Effect 10 • Transposition • Kohler’s idea that animals learn relationships between stimuli and that they respond to different stimuli based on the same relationship as the original training stimuli. • Implies Relational Learning
Lawrence & DeRivera (1954) Study 11 • Training: White or Pale Gray or Light Gray = Right Mid Gray Mid Gray Mid Gray • One of the Test Trials: Light Gray = ? White • Which way did the rats turn on this test trial?
Examples 12 Absolute top See white = R Relative See white = Right See pale = Right Darker = L See dark = Left See darkest = Left
Results 13 • Test: Light Gray White • Result: the rats turned LEFT! • Strong evidence for relational learning
Complex Stimuli and Attention 14 • What if stimuli are tested which have multiple dimensions? • Sutherland-Mackintosh attentional theory • Pay attention to the relevant dimension (called “analyzer”) • Learn which values along the dimension signal reward S+ or nonreward S-.
Train Test Grp 1 Grp 2 S+ S+ S+ S- S- S- Grp2: Intradimensional > Grp 1:Extradimensional
More Complex Tasks Later pigeons were asked to place images into four categories by pressing one of four buttons (rewarded by food if correct). They are “naming” the object shown. Pigeons do equally well with natural and manufactured objects (cars, chairs). Transfer to new stimuli is worse but above chance. 20
