Stimulus Discrimination and Control

Lesson Overview

• Topics to Discuss:

  • Stimulus Discrimination

  • Stimulus Control:

  • Simultaneous Discrimination

  • Successive Discrimination

  • Matching to Sample

  • Oddity Matching

  • Errorless Discrimination Training

Stimulus Discrimination and Generalization

• Examines the relationship between discrimination and generalization.

Stimulus Discrimination

• Definition: Discrimination training is a procedure to establish discrimination in both Pavlovian (Involuntary) and operant conditioning (Voluntary).

• Example: Pavlov's dogs were fed when an object rotated clockwise (CS+) but not when it was counterclockwise (CS–).

• Operant Example: A rat is rewarded for pressing a lever when a light is on (SD) but not when it is off (S∆).

• Important Note: Discrimination must be taught.

Discrimination Training

• Definition: Any procedure to establish discrimination.

• Distinction is made between Pavlovian and operant discrimination training.

• Discriminative Stimulus (SD): In operant training, signals that a behavior will be reinforced (SD) or not (S∆). In Pavlovian training, refers to a CS that predicts the presence (CS+) or absence (CS–) of a UCS.

Methods of Discrimination Training

• Different Training Methods:

  • Simultaneous Discrimination

  • Successive Discrimination

  • Matching to Sample

  • Oddity Matching

  • Errorless Discrimination Training

Simultaneous Discrimination Training

• Definition: Both SD and S∆ are presented simultaneously.

• Example: A rat approaches one of two doors; one opens for food (SD) and the other leads to a net below (S∆).

Successive Discrimination Training

• Definition: SD and S∆ are presented one after the other in a random sequence.

• Example: Horses pressing a lever for a large circle (SD) earn reinforcement; a small circle (S∆) does not.

Matching to Sample

• Definition: Select the comparison stimulus that matches a sample from two or more options.

• Example: Pigeons peck a red disc (SD) when a red disc is lit (sample); other color options act as S∆.

Oddity Matching

• Definition: Reinforcement is given for selecting the option that is different from the sample.

• Structure: Similar to matching to sample but selects the differing stimulus as the SD.

Errorless Discrimination Training

• Definition: Introduces S∆ weakly and gradually increases its strength and duration.

• Example: In training pigeons, the SD (red disc) is intense and present longer than the weak S∆ (green disc).

Stimulus Control

• Definition: Behavior occurs in the presence of an SD but not an S∆.

• Behavior Under Control: E.g., rats pressing levers when lights are on but not off, or stopping at red lights (situational behavior).

Benefits of Stimulus Control

• Encourages efficient use of time and energy by only reinforcing behaviors in certain contexts.

• Enhances safety and efficiency (e.g., attending to traffic signals).

  • Prevents futile behaviors (e.g., unwanted snacking).

Lesson Summary

• Revision of discrimination training and the various methodologies:

  • Simultaneous Discrimination

  • Successive Discrimination

  • Matching to Sample

  • Oddity Matching

  • Errorless Discrimination Training

Lesson Reading

• Source: Learning and Behavior: Active Learning Edition. 8th ed., Chapter 11.