- Preference assessments find what the client likes.
- Formats: paired stimulus, MSWO and free operant.
- Preferences change, so check often.
- Confirm reinforcement by watching the effect on behavior.
Why run preference assessments?
Reinforcement only works if the consequence actually matters to the client. Preferences shift with mood, time of day and satiation. Conducting preference assessments is part of RBT training in the 2026 curriculum.3
What are the main formats?
| Format | How it works | Good for |
|---|---|---|
| Paired stimulus | Two items at a time; every pair presented | Clear rankings; clients who can choose between two |
| MSWO | Several items at once; chosen item isn't replaced | Quicker rankings of several items |
| Free operant | Items available; record time engaged with each | Clients who find choosing hard; no items removed |
| Brief check | Offer 2 or 3 options before a task | Every session |
The paired-stimulus format was evaluated by Fisher and colleagues, and the MSWO by DeLeon and Iwata.12
How do I run an MSWO?
- Put 5 to 8 items in a row in front of the client.
- Say "Pick one."
- Let them engage briefly with the chosen item.
- Remove it, rearrange the rest, and repeat until all are chosen or none are.
- Rank items by order of selection. Repeating the array across sessions gives more reliable rankings.
What else should I watch for?
Try
- Checking preferences at the start of every session
- Rotating items to avoid satiation
- Noticing assent: does the client still want this?
Skip
- Using the same reinforcer for months
- Assuming yesterday's favorite still works
What can I do this week?
0 of 3 done
Read next: How do I use a token economy in ABA?
