Trial-Based Methods
Several options for trial-based methods are reviewed here. The trial-based methods are group by how the stimuli are presented: single stimulus, paired stimuli, and multiple stimuli. Note the differences in the methods with regard to time and amount of items assessed.
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Single Stimulus
Like the name suggests, the single stimulus preference assessment presents a single item or activity to a client. The client’s response to the item is recorded as whether the client accepted or rejected the item. If the client accepts the item, the total time the client engages with the item is recorded.
The single stimulus method is a not very efficient. Few items may be assessed over a long period of time. Some clients may engage with a single toy for 20 minutes or more. Below are some guidelines for use of the single stimulus method.
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- A great method for clients who have difficulty with choosing an item from an array
- An option to consider for a client who engages in aggressive behavior when items are taken back
- May be a way to introduce new items to clients and gauge their reaction
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- Allows client to satiate on preferred items, so it is not a practical option to do before a work session
- Will likely will several sessions to implement
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Paired Stimuli
The paired stimuli method of preference assessment is just like it sounds, two items are presented together and the client’s choice is recorded. All the items are paired through the course of the session. The pairings are meant to be in a random, mixed-up order so that the client is not receiving the same items repeatedly in consecutive trials. The number of times the client picked each item is tallied. The items are then placed in order from most preferred to least preferred. In the application below, the data sheet and questions for analysis demonstrate how the data are collected and analyzed.
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What is the difference between the paired stimuli method and pre-task choice?
Both methods offer the client a choice of two items assume that the item the client selects will be a more powerful reinforcer over the item that was not selected. The difference is that pre-task choice is a single trial of two items. The paired stimuli preference assessment involves more than just two items. It is also more complete because the result is a list of items in order of preference. Practically speaking, the paired stimuli method requires several trials and conducted infrequently and the pre-task choice is a single trial typically conducted several times per day.
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