Paired Stimulus Preference Assessment
A Pared Stimulus Preference Assessment allows a teacher to create a hierarchy of the child’s preferences. In a Pared Stimulus Preference Assessment, the teacher presents two items each trial and asks the child to make a choice. Pared Stimulus Preference Assessments are as thorough as MSWOs and MSWs, but more time-consuming to conduct, because they require more trials. Thus, these are appropriate for children who are able to choose highly-preferred items over low-preferred items, but are unable to scan more than two items on a surface.
Because toys must be taken away after each trial and are not necessarily replaced in the array, this is not an appropriate assessment for children who engage in problem behavior when preferred items are taken away. If a child is unable to choose highly-preferred items over low-preferred items, or demonstrates a side bias (i.e., selecting items only on one side), a Single Stimulus Preference Assessment or Free Operant Observation should be conducted. In a Paired Stimulus Preference Assessment, the teacher places two items (usually toys or edibles) in front of the child, and allows him or her to select one. After the child plays with or consumes the item, the teacher presents another trial of two items. Each time the teacher presents two items, this is known as one trial. The teacher repeats trials until every item has been paired with every other item, in “round robin” style. Typically, the items the child selects during the most number of trials are the child’s highest preferred items of the array, and the items the child selects for the fewest number of trials are the child’s lowest preferred items. The highest preferred items are more likely to serve as reinforcers, or items that will reinforce targeted behaviors. However, keep in mind that not all preferred items function as reinforcers. It is important to (a) perform single stimulus Preference Assessments regularly because preferences may change, (b) assess a possible side bias by alternating the locations of items, (c) use a combination of likely preferred and non-preferred items to confirm that the child is making choices based on preference, and (d) regularly assess whether the child is able to scan three or more items on a surface, as MSWOs and MSWs are more efficient than Pared Stimulus Preference Assessments.
Before beginning, you should collect the following materials:
Data collection sheet
4-6 bite-sized edible items or 4-6 toys
Now you and your child are ready to begin.
- Sit across from the child at a table or on the floor.
- Place items two items (i.e., items A and B) on the table. If the child is unable to wait until your task direction to make a selection, block view of the items with a large book or clipboard.
- Lift the book or clipboard (if you are blocking the child’s view), and give the task direction, “Pick one” or “Which one do you want?”
- If the child reaches for both items, block access to the items, and repeat the task direction, “Pick one” or “Pick one for now. We’ll pick another one next.” If the child continues to make this error across several trials, you should consider conducting a Single Stimulus Preference Assessment or Free Operant Observation.
- Allow the child to consume the edible item or play with the toy. Block access to the remaining item during this interim.
- While the child is consuming the edible or playing with the toy, set up the next array of items, according to your data sheet (i.e., items A and C).
- If you are using toys, allow the child to play with the toy for 15-30 seconds, and remove the toy in order to present the next array. If the next array includes the most recently selected item, alternate the side of the item, in order to detect for side bias. For every trial, you will present two items, according to your data sheet, and this may or may not include the toy the child most recently selected.
- If the child refuses to make a selection, move to the next trial. Repeat steps 4-7 until the set number of trials is complete. If the child is unable to complete all trials (e.g., stops making choices, engages in problem behavior) the assessment may need to be completed as multiple sessions with fewer trials.
To cite this page (APA 6th edition):
- Chazin, K.T. & Ledford, J.R. (2016). Paired stimulus preference assessment. In Evidence-based instructional practices for young children with autism and other disabilities. Retrieved from http://vkc.mc.vanderbilt.edu/ebip/paired-stimulus