Preference assessment is a tool commonly used in ABA therapy. It helps identify the items that children are most interested in and eventually use these items as reinforcers to motivate learning. In this article, we review different preference assessment types used by ABA therapists.
What Are Preference Assessments?
Preference assessment is a procedure that allows ABA therapists to determine the hierarchy of a child’s preferred items, from low preferred to highly preferred ones. This method can be used to determine hierarchies of everything from toys and foods to social interactions, people, and locations.
Highly preferred items are potential reinforcers that can be used as motivators during therapy sessions. If a child is given the possibility to choose a preferred reinforcer, a target behavior is more likely to occur.
However, while preference assessments may indicate what items or actions the child prefers, it is not always possible to know whether they will become effective reinforcers, until they bring about an improvement in the target behavior.
How often are preference assessments conducted?
ABA therapists may choose to assess potential reinforcers very frequently, for example, during every therapy session, or less often, for instance, once per month. The frequency of preference assessments will depend on the individual needs and functioning level of each child.
Assessments may need to be done more often if a child’s preferences change frequently or when a child’s behavior indicates that a current reinforcer is no longer preferred.
If a child communicates verbally, the therapist can check in about his or her preferences as frequently as needed. However, when it comes to children with autism who have impaired language skills, the therapist has to work with parents and teachers to establish any changes to the child’s preferences.
Why Use a Stimulus Preference Assessment?
Since positive reinforcement is one of the most important elements of ABA therapy, it is crucial to conduct preference assessments that will determine the most effective reinforcers. This systematic, data-based approach to evaluating a child’s potential interests can significantly improve the learning of new skills.
In the following section, we explain the different preference assessment procedures used in ABA therapy.
The Three Types of Stimulus Preference Assessments
ABA therapists use the following methods to identify potential reinforcers:
- Free operant observation
- Trial-based method
The asking method consists of the therapist asking either the child or caregivers, parents, teachers, and friends about the child’s preferences. This can be done by:
- Asking open-ended questions
- Asking comparison questions
- Offering a pre-task choice, such as asking the child what they would like to earn for completing the task
- Showing visuals with pictures of items or activities
- Asking for a rank-ordering of items.
Because some children with autism may have difficulty communicating their preferences directly, ABA therapists must consider alternative methods of obtaining the information, for example, interviewing individuals in the child’s environment. Interviews are a straightforward technique that can be used to quickly gather information about the child’s preferences. The resulting information is compiled into a list and the therapist can then test out the identified items as possible reinforcers.
Using formal surveys, such as the Reinforcement Assessment for Individuals with Severe Disabilities (RAISD), is another way to gather information about potential reinforcers across a variety of domains, including:
- Activities (running, dancing, swinging)
- Objects (mirrors, shiny objects, spinning toys)
- Foods and snacks (ice cream, pizza, juice)
- Sounds (music, car sounds, whistles)
- Smells (flowers, perfume, pine trees)
- Forms of attention (a hug, a pat on the back, verbal praise).
Subsequently, the therapist ranks the choices in different categories in order of preference. Although simply asking about a child’s favorite items and activities is a fast and easy procedure, relying on this method alone may result in incomplete or inaccurate information.
Free operant observation
Free operant observation consists of determining what items the child gravitates toward and interacts with spontaneously. The child is given free access to items or activities that he or she may like (presumed preferences) without any demands or restrictions.
The therapist records the amount of time the child engages with these items and makes note of the child’s positive emotions, such as smiling or laughing. The longer the interaction, the higher preference value is given to the item.
Free operant observations can be:
- Naturalistic, where the child engages with items freely in their natural environment, or
- Contrived, where the child is offered specific items in a learning setting and the therapist observes which of these items the child chooses to engage with.
Trial-based methods are different formal techniques used to determine potential reinforcers. They include the following:
- Single stimulus method
- Paired stimuli method
- Multiple stimuli method.
Single stimulus method
Single stimulus or successive choice is the simplest trial-based method. The therapist presents an item (stimulus) to the child and records the child’s reaction. The single stimulus method is typically used for establishing the preferences of children with autism who have difficulties choosing between two or more items.
Paired stimuli method
Paired stimuli or forced choice consists of presenting two items at the same time and recording the child’s choice. Individual stimuli are randomly paired and presented to the child. The therapist then collects the data on the number of times the child chose each item.
Multiple stimuli method
The multiple stimuli method refers to presenting the child with three or more items simultaneously. This method has two variations:
- Multiple Stimuli with Replacement (MSWR), where the chosen item remains in the array, while all the items that were not selected are replaced by other items, and
- Multiple Stimuli without Replacement (MSWOR), where the chosen item is taken out of the array without being replaced by any other items.
How to Conduct Preference Assessments
Preference assessment is a two-step process. To begin with, the therapist gathers a number of stimuli that may serve as potential reinforcers. Assessment is then conducted by presenting the child with these stimuli and determining preferences through asking, direct observation, or a trial-based method.
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