Single Stimulus Preference Assessments
Single Stimulus Preference Assessments, also known as “successive choice” assessments, are conducted by providing a single item to a child, and recording his behavioral response to each item, as well as the duration of his engagement with each item. Although Single Stimulus Preference Assessments may not be as accurate at determining preferences as MSWOs, MSWs, and Paired Stimulus Preference Assessments, these are appropriate for children who are unable to select between highly-preferred and low-preferred items. For example, if you conduct a Paired Stimulus Preference Assessment and noticed that the child always selects items from one side (i.e., side bias) or always attempts to take both presented items, a Single Stimulus Preference Assessment should be used instead.
In addition to being appropriate for children unable to scan a field of two items, Single Stimulus Preference Assessments are also appropriate for children who engage in challenging behavior when preferred toys are taken away, because children are allowed to continue engaging with toys until they choose to stop or give them up. These may not be appropriate if you have limited time to conduct assessments, because each item is presented sequentially, and the child is permitted to engage with the item as long as they choose. Thus, these assessments can be quite time consuming. Alternatively, you can set a relatively long time limit for each trial. For example, you can discontinue a trial at a maximum duration (e.g., 5 minutes) and record “max” for that item.
In a Single Stimulus Preference Assessment, the teacher places a single item in front of the child, and allows the child to approach it and engage with it. After the child finishes consuming the edible or stops playing with the toy, the teacher removes the toy (if applicable) and presents another item. Each time the teacher presents one item, this is known as one trial. The teacher repeats trials until every item in the array has been offered to the child, or until the child consistently rejects or does not approach every item. Typically, the items the child approaches consistently and engages with for the longest are considered the child’s highest preferred items, and the items that the child does not approach or responds to with avoidant/problem behaviors are considered the child’s lowest preferred items. It is important to (a) perform Single Stimulus Preference Assessments regularly because preferences may change, (b) use a combination of likely preferred and non-preferred items to confirm that the child is approaching items based on preference, and (c) regularly assess whether the child is able to scan two or more items on a surface, as MSWOs, MSWs, and Paired Stimulus Preference Assessments may be more efficient and accurate than Single Stimulus Preference Assessments.
Before beginning, you should collect the following materials:
Data collection sheet
3-10 bite-sized edible items or 3-10 toys
Stopwatch or clock
Now you and your child are ready to begin.
1. Sit across from the child at a table or on the floor.
2. Place a single item from your array within reach of the child, and give the task direction, “Do you want it?” You may manipulate the toy as intended to show how it works.
3. If the child approaches the item (i.e., reaches out or takes it from you) and begins playing with it, allow the child to continue engaging with the item until they reject it (i.e., put it back the table, turn away from the item).
4. If the child engages in problem behavior, has an avoidant response (see definitions below), or does not approach the item within 10 s, remove the item.
5. Record the following on your data sheet during each trial:
- Whether the child approaches the item (i.e., reaches out and takes it). If the child has limited motor abilities, approaching the item may mean that you place the item in front of the child, in his hands, or in his lap, and the child does not resist or reject the item. If the toy is novel, you might consider pushing buttons on the toy to show how it works. If the child does not approach the item within 10 s, remove the item.
- Whether the child engages with the item. For engaging with toys, this might include pushing buttons on the toy, swinging the toy around, or otherwise manipulating the toy. Engagement does not necessarily have to be manipulating the toy as it was intended, but should not include problem behavior (e.g., throwing the toy, breaking the toy). For engaging with edible items, the child engages with the item if he consumes it.
- Whether the child has an avoidant response to the item or engages in problem behavior. This might include turning his head away from the toy, whining,
screaming, aggressing, breaking the item into pieces, or throwing the item (unless throwing is an appropriate play action, e.g., with a ball). Avoidant responses and problem behavior should only be recorded during the initial presentation of items, and not after the child has engaged with the item.
- The duration for which the child plays with the toy (i.e., the amount of time between the child’s approach and rejection of the toy). It is not necessary to record duration for consuming edible items.
6. Repeat steps 1-5 until you have completed your pre-determined number of trials or until the child consistently rejects or does not approach any it.
To cite this page (APA 6th edition):
- Chazin, K.T. & Ledford, J.R. (2016). Single stimulus preference assessment. In Evidence-based instructional practices for young children with autism and other disabilities. Retrieved from http://vkc.mc.vanderbilt.edu/ebip/single-stimulus