ABA Therapy Basics

This page gives a brief overview of Applied Behavioral Analysis (ABA) therapy, which has been used successfully by Lovaas, et. al., to treat young autistic children. NOTE: this was written by an amateur who cannot speak (or write) authoritatively on the subject. This is intended to provide just enough information about ABA therapy to explain how the "ABA Math" software works.


ABA therapy breaks each learning task into several (sometimes many) sub-tasks. For example, to teach a student the task of writing a mark on a piece of paper may require that he first be taught the sub-tasks of picking up a pencil, locating the pointed end, holding the piece of paper, running the point of the pencil against the paper, etc. The number and complexity of sub-tasks will vary with each student.

Each sub-task is taught separately using (sometimes many) discrete trials wherein the student is asked (once) to perform the task. Only after he has done it correctly a certain number of times, and without assistance from the therapist, is the sub-task considered mastered. Then the program moves on to the next sub-task.

ABA therapy is also characterized by data. The therapists keep records on the results of each trial, for each sub-task, of each task the student is taught. Performance is therefore easily quantified. ABA therapy generates a lot of data.

Definition of Terms

  • Sd (Discriminative Stimulus): The command given to the student, e.g., "do this".
  • R (Response): The student's action in response to the Sd, usually one of: correct response, incorrect response, no response or response with prompting.
  • Sr (Reinforcing Stimulus): The therapist's reponse to the student, e.g., "Good job!" or "oops, try again." Edible treats, praise, hugs, etc. are also Sr's.
  • Discrete Trial: The sequence Sd-->R-->Sr. There is only one Sd and each trial is scored.
  • Prompt: Assistance given to the student to help him along. It may be as simple as a nudge in the right direction or as intrusive as "hand over hand" modeling of the desired action. The least intrusive possible prompt is always used whenever a prompt is necessary.
  • Acquisition Item: The item being learned.
  • Mastered Item: A item that has already been learned.
  • Receptive: A program where the student acts on a direct command, e.g., "Touch pencil".
  • Expressive: A program where the student answers, e.g., Sd="What is this?", R="a pencil".

Stages of Descrete Trial Teaching

  • Mass Trial (MT): Same Sd given each trial, with only one choice offered, e.g., "Touch pencil", when a pencil is the only item on the table.
  • Distractor Trial (DT): Same Sd given each trial, with several choices offered, e.g., "Touch pencil", with a pencil and two other "distractor" items on the table.
  • Random Rotation (RR): Similar to DT, but the other items are previously mastered items, and the Sd is usually for the aquisition item but is sometimes for one of the others.
  • Review: A random testing of previously mastered items.

How ABA Math Uses These Methods

ABA Math uses seven stages for each acquisition item, three receptive and four expressive. The aquisition item is a single math fact such as "1+2=3". At each stage the student must answer correctly a number of times (4 by default) before going on to the next stage.
  1. MT-receptive: Acquisition item (AI) in one of three random locations. Student asked to click on it.
  2. DT-receptive: AI + 2 distractors. Student asked to click AI.
  3. RR-receptive: AI + 2 Mastered items. Student asked to click one (AI about half the time).
  4. MT-expressive: AI problem + AI answer in random locations. Student asked to click answer.
  5. DT-expressive: AI problem, AI + 2 distractor answers. Student asked to click answer.
  6. RR-expressive: AI or MI (AI about half the time) + 10 answers. Student to click answer.
  7. Review: Either AI or MI randomly chosen, 10 answers. Student to click answer.
After each correct response the student is praised with a verbal "good job!" After each completed stage he is rewarded with a pleasing animation. Whenever the student fails to response within a set time (8 seconds by default), he is prompted with a flashing border around the correct item and a "click here" command.