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.