Discrimination Training

Discrimination is demonstrated when a response is more likely to be emitted under specific stimulus conditions and less likely under others. That is, the probability that a student will emit a specific behavior is increased in the presence of a specific stimulus or stimulus class called a discriminative stimulus (SD). An SD signals that reinforcement is available for the behavior under its control. When a specific response occurs more frequently in the presence of an SD than in its absence, it is said to be under stimulus control. The process of training or teaching a student to respond in the presence of a specific stimulus is referred to as discrimination training. For example, when a person picks up a phone when it is ringing but not when it does not ring, that person's behavior is under the control of the SD “ringing of the phone.” When a student says “Blue” in the presence of a blue block but not in the presence of a red block, the student is discriminating between colors (or at least between red and blue). [Page 1275]If, as in the case of a student with developmental disabilities, the student is taught to identify blue versus other colors, discrimination training has been conducted.

Most educational practices are based on simple discrimination training, using the behavioral principles of reinforcement and extinction. The desired response is reinforced when emitted in the presence of the SD. Knowing when and where to demonstrate the target behavior is only one part of discrimination training. It is equally important that the student learn when the target behavior should not be demonstrated, will be less likely to yield reinforcement, and may yield punishment. A stimulus that signals that a response will not be reinforced is called an S-delta. If nonpreferred or incorrect responses are emitted in the presence of the SD, reinforcement is withheld or withdrawn. Therefore, the same stimulus serves as a discriminative stimulus for some responses and as the S-delta for others.

The basics of discrimination training were established and well documented in the literature on basic experimental behavior analysis. When a pigeon is repeatedly and systematically reinforced with food for pecking the red key and not reinforced for pecking the black key; and the pigeon now pecks the red key consistently and ignores the black key, the pigeon is described as making a discrimination. The process of teaching that discrimination is called discrimination training.

To determine through data evaluation and analysis whether discrimination has occurred, the target behavior must be observable and measurable. Young students or students with significant disabilities may be taught simple discriminations. As students get older and the curriculum becomes more complex, so do the discriminations and the stimulus control situations that must be implemented to teach the discriminations. Although the discriminations differ in complexity, instructions in length, and reinforcement schedules in density, the same basic behavioral principle of discrimination is employed to teach a young child with mental retardation the difference between shapes and a college student the difference between mathematical formulas.

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