6 Discrimination Training

Stimulus control and discrimination

Discrimination training teaches a learner to respond differently to different stimuli. The goal is for the relevant cue to guide the response reliably, rather than an accidental feature or extra prompt.

Stimuli acquire their functions through their history with responses and consequences. Discrimination is demonstrated when responding is more likely in the presence of the discriminative stimulus than in the presence of the S-delta.

Choosing cues and arranging stimuli

A spoken instruction can help control which item a learner selects. For example, a learner might select a spoon when asked, “Show me the spoon,” and not select it when asked, “Show me the fork.” In a conditional discrimination, the correct choice depends on the preceding cue: the learner selects the spoon after hearing “spoon” and the fork after hearing “fork.”

Choosing stimuli and relevant features

Begin by identifying the skill and the cue that should naturally occasion it. Choose clear, appropriate examples and comparison stimuli. At first, make relevant differences easy to notice; later, teach distinctions among more similar examples if the skill requires it.

Stimulus disparity describes how different the stimuli are, while salience describes how noticeable a feature is to the learner. A stimulus can vary in color, shape, size, and position. Plan which feature should control the response, and avoid allowing irrelevant features to do so.

For example, when teaching selection of a spoon from an array, vary its position across trials. If the spoon is always on the left, the learner may respond to its position rather than to the spoken cue and utensil. Use multiple examples and vary irrelevant features when appropriate so responding does not become restricted to one picture, color, or arrangement.

Teaching and fading extra cues

A practical teaching sequence is:

1. Present the natural cue and the relevant choices.

2. Give the learner an opportunity to respond, using a planned prompt if needed.

3. Reinforce correct responding and record whether it was independent or prompted.

4. If an error occurs, use a consistent, supportive correction procedure and offer another opportunity to respond.

5. As responding improves, systematically reduce the prompt or added cue. Continue until the natural cue evokes the response without that extra help.

For example, when teaching “Show me the spoon,” an instructor might initially point toward the spoon while giving the spoken instruction. Across opportunities, the point can become smaller, less direct, or delayed while the instruction and choices remain. The aim is for the learner to select the spoon upon hearing the instruction without needing the point.

Prompt fading transfers control from the temporary prompt to the intended cue. Stimulus fading is a related method in which an added feature, such as a bright outline around the correct item, is gradually changed until it is removed. Prompt-fading procedures should be systematic and guided by the learner’s responses. If prompts remain in place too long, they can become cues the learner waits for.

Monitoring and adjusting instruction

Track accuracy, prompt level, and the learner’s choices across trials. Look for patterns such as repeatedly choosing the same position, responding only when given a gesture, or attending to an irrelevant picture feature.

If errors persist, reconsider whether the cue is noticeable, whether the choices are sufficiently distinguishable, or whether the prompt is obscuring the intended cue. Adjust instruction to the learner and skill rather than assuming that one fading procedure will work for everyone.

Reliable, differentiated responding depends on selecting stimuli that make the target distinction teachable, arranging reinforcement so correct and incorrect choices differ meaningfully, and checking for control by accidental features. Prompts and added stimulus cues can support early learning, but should be faded systematically so the intended natural cue—not the extra help—guides the response.