Types of Preference Assessments Used in ABA: Multiple Stimulus Without Replacement

The Multiple Stimulus Without Replacement (MSWO) method is a behavioral assessment technique used extensively in therapeutic settings, especially for individuals with developmental disorders such as autism spectrum disorder (ASD). It is designed to determine the preferences of an individual by allowing them to select from a variety of options, and it is particularly useful when the aim is to establish a clear hierarchy of preferences.

Here's how the MSWO method works:

Presentation: A range of items or stimuli (typically 3 to 5) is presented simultaneously to the individual.

Choice: The individual selects one item from the array.

Removal: Unlike the Multiple Stimulus With Replacement method, the chosen item is not returned to the array. The remaining items are presented again for the next choice.

Recording: The observer notes which item is chosen in each round until all items have been selected or the individual stops making choices.

The process helps in identifying not just the top preferences, but also in ranking all available options based on the order of selection. This ranking can be very insightful for therapists and educators as it shows not only the most preferred items but also how other items compare when the most preferred are not available.

MSWO is particularly valuable because it reduces the total time required for the assessment by not repeating items, making it efficient and effective in settings where time and attention span may be limited. This method provides a clear preference hierarchy that can be used to tailor interventions, motivate individuals in therapy, or enhance learning experiences by incorporating highly preferred items or activities.