| Type | Structured observation used within a diagnostic evaluation (not a screen, not standalone) |
|---|---|
| Age range | Modules covering toddlers through verbally fluent older children and adults |
| Format | Roughly 12–20 minutes; a caregiver plays with the child using set materials while the clinician observes and codes from a distance |
| Origin | Catherine Lord and colleagues, 2020 — derived from the BOSCC and the same tradition as the ADOS-2 |
| Who administers | Clinicians trained in ADOS-2/BOSA coding |
How it differs from the ADOS-2
In an ADOS-2, the examiner is the social partner: they create the "presses" and observe how the child responds to them. In a BOSA, the parent is the social partner and the clinician steps back to watch. That single change has three practical consequences:
- It works at a distance — the original reason it exists, and still useful when infection control, sensory overwhelm, or a child's distress makes close examiner contact a bad idea.
- It's much shorter — minutes rather than an hour, which is why some clinics use it to keep evaluations moving when full ADOS-2 slots are scarce.
- It shows the child with a familiar person — arguably more representative of everyday interaction, and at the same time a different thing than what the ADOS-2 measures, since responding to a parent and responding to a stranger are not the same social task.
Newer means less evidence. The BOSA has nothing like the ADOS-2's decades of validation behind it, and it produces a briefer sample of behavior. It is best understood as one structured observation contributing to a clinician's overall judgment — not as an equivalent substitute. If your child's evaluation used a BOSA and the conclusion was "not autistic" while your concerns persist, that is a reasonable moment to ask whether a full ADOS-2 or a second opinion is warranted.
If your child is scheduled for one
You will be the one playing, which surprises many parents. The guidance is the same as for the ADOS-2 and easy to state, hard to do: play normally. Don't coach, don't prompt extra eye contact, don't work harder than you would at home to keep your child engaged — the clinician is trying to see the ordinary version of your interaction, and an unusually managed one gives them less to work with, not more.
Around the observation, a complete evaluation still includes a developmental history (ADI-R or equivalent), cognitive and language assessment, adaptive functioning (Vineland-3), and a hearing test — all judged against the diagnostic criteria.
Medical disclaimer: Educational information only. The BOSA belongs to its authors and publisher. This page cannot diagnose anyone; consult a qualified clinician.