Analysis of four measures of positional bias within a multiple stimulus without replacement preference assessment

Miranda et al. (2023) watched 19 autistic preschoolers do an MSWO. They tracked four easy ways to spot if kids always pick items in the same spot.

The four checks were: count of left vs right picks, center vs edge picks, how far each item's score drifts, and a quick binomial test.

Most kids showed almost no positional bias. The four metrics differed in how picky they were and how fast you can do the math.

No single metric flagged every child, so the team says just pick one method and stay with it.

Melanson et al. (2023) looked at the same MSWO setup the same year. They found that kids changed their top picks 40% of the time within one session. Miranda's low bias numbers help explain why: items move around because preferences shift, not because kids love the left tray.

Moore et al. (2017) showed that bigger stimulus cards can nudge low-preference items up the list. Miranda adds that where you place the cards matters less than we feared, so size and left-right spot are separate worries.

Wanchisen et al. (1989) proved that even a tiny presession choice wipes out problem behavior. Miranda gives a quick way to check that those choices are real, not just a kid hugging the right side of the table.

You can now run MSWO and know that spot-hogging is rare in preschoolers. Pick one bias metric—side counts or preference drift—and spend one minute after each assessment. If numbers look even, press on. If not, shuffle the trays and rerun. This keeps your reinforcer list honest without extra gear or time.