Understanding Stimulus Discrimination Training and its Role in ABA Therapy


Stimulus discrimination training is an essential part of Applied Behavior Analysis, especially for autistic individuals. This technique teaches people to respond to various stimuli in the environment by distinguishing between their characteristics in any situation. Learners’ appropriate responses to specific stimuli are then reinforced. For example, teaching a child to point at and say “cookie!” when he wants to eat one, and then reinforcing this behavior by giving him cookies.

Stimuli in the environment can be anything - the time of the day, the weather, food on a plate, a color, an object, a person, etc. Stimulus discrimination training can use any or all of these to bring about a certain behavioral outcome in the presence of that stimulus, and then reinforce that behavior so it continues in the future.

Basic Concept of Stimulus Discrimination

Stimulus discrimination revolves around the idea of teaching a specific response to a specific stimulus. People learn how to differentiate between a mixture of different stimuli to target the relevant one and disregard others. Successful behavior shall be reinforced while incorrect responses may not be addressed, a principle known as differential reinforcement.

Types of Stimuli in Discrimination Training

Stimuli in the environment can be broadly categorized as relevant or irrelevant. The context of the situation dictates what is categorized as either of these. For example, in a classroom, a teacher’s instruction to “open your textbooks” is a relevant stimulus to opening a textbook and a friend’s call to talk or play a game is irrelevant.

Effective stimulus discrimination training just like Natural Environment Teaching is important to teach people to focus on the relevant stimulus while filtering out all irrelevant stimuli. This promotes adaptive behavioral learning, and enhancement of the ability to concentrate and function effectively in various situations.

Discriminative Stimulus

When a desired response to a stimulus is positively reinforced, the learner develops a strong association of that outcome with that stimulus. Over time, and after repetitions, that stimulus becomes the discriminative stimulus or SD for that desired response.  This means that when the stimulus is in the environment, the response follows. 

It is important to note that the likelihood of the desired outcome or response is directly related to the presence of the SD, and in its absence, the person will most likely not indulge in the desired behavior.

For example: if a telephone is just sitting in a room, you may not react to it, but if that phone rings, you will probably answer it because the behavior of answering the telephone after it rings has been reinforced by a person on the other end, while the behavior of answering the telephone absent of ringing, has not been reinforced.

Here are some more examples of discriminative stimuli to illustrate what SD looks like in everyday life:

Discrimination stimulus (SD) Desired Behavior Reinforcement
Sound of the bell for lunch break at school Going to the cafeteria for lunch Eating lunch
Doorbell sound Opening the door Greeting a visitor
Stop sign on the road Stop driving the car Safe from potential car accident
A hand towel next to the basin in the toilet Wiping hands dry after washing them Having clean, dry hands.
Mother Identifying mother in a group by saying “mama” Receiving mother’s attention.

Stimulus Delta

Stimulus delta is the collection of all options that should be disregarded in a given situation because they show that a reinforcer is not available, and thus proceeding with the same behavior will not result in the desired or expected reinforcement. Since responding to the incorrect stimulus is not reinforced, and may even be punished by someone telling you that it is incorrect, people are discouraged from associating the outcome with that stimulus and repeating this result in the future.

For example, in the context of a fruit basket, if the learner is asked to pick out an apple, then all other fruits in the basket are the stimulus delta. If the individual selects a banana instead of an apple, he will be prompted to try again instead of getting to enjoy the fruit.

Stimulus delta is important as it helps learners understand when a certain behavior will be reinforced and when it will not be, and also which stimuli are necessary for the desired reinforcement. This helps people deliver more appropriate and context-relevant responses.

The following table shows the stimulus delta for the examples of discrimination stimulus mentioned earlier:

Discrimination stimulus (SD) Resulting Behavior
The bell not ringing for the lunch break at school Remain seated in the classroom
No doorbell sound Not opening the door/not greeting people
Red light at the traffic signal Stop driving the car/avoid accidents
No hand towel next to the basin in the toilet Not washing hands/not drying hands
Mother not present in a group of people Saying “mama” will not result in the mother’s attention.

Benefits of Stimulus Discrimination Training in ABA

Stimulus discrimination training lays the foundation for a good life for people in general, including those with developmental disorders such as autism. It enhances basic life skills and essential capabilities such as asking for help or preparing a meal so people learn to enjoy independent lives. The technique is highly beneficial for anyone who learns to implement it.

  • Improved learning adaptation: people acquire new skills and develop them when their correct responses and presentation of desired behaviors are consistently reinforced. Students also receive benefit, as they learn to perform well in classes and assignments.
  • Enhanced focus: this technique also allows people to concentrate on what is important and sustain that concentration for an extended period as stimulus discrimination training helps the learner to filter out irrelevant stimuli to restrict distractions.
  • Better communication and social skills: stimulus training significantly improves communication and interpersonal skills. People not only learn to talk to others with confidence, initiate conversations, and ask for help, but also recognize the benefit of laughing at a joke or expressing concern when hearing sad news.
  • Increased independence: as individuals become confident in successfully completing tasks or easily navigating through a challenge, they become less dependent on others - their success in these little victories of day-to-day life is not centered around the presence of their therapist, caregiver, or parent.


Stimulus discrimination training allows people to distinguish between various stimuli so they can respond to the one that will give them the desired natural reinforcement or outcome. As they learn to differentiate between the relevant and irrelevant signals, they become more capable of completing the task at hand or achieving the end goal of the activity. It enhances independence, social and communication skills, concentration span, and learning abilities - all skills necessary to improve the quality of life and live life with ease and freedom.


Integration-Specific Demos

Aug 7
3:30 pm
Aug 8
3:00 pm
Brian Curley
Chief Creative Officer