Effects of idiosyncratic stimulus variables on functional analysis outcomes.

Smith et al. (1997) wrote a think-piece, not an experiment.

They warned that hidden triggers—like a certain smell, a backpack, or one staff member—can flip functional analysis results.

The paper gives a checklist to hunt for these sneaky stimuli when data look odd.

The team showed that unnoticed idiosyncratic stimuli can make problem behavior look attention-based when it is really escape-based, or vice-versa.

They offered clinical signs that cue you to probe: bouncing results, no clear pattern, or behavior that spikes only with one therapist.

Later work tested the warning in real clinics. Rose et al. (2000) added colored rooms and different therapists; four of eight kids finally showed a clear function, proving cues can save an unclear FA.

Matson et al. (2013) ran the same FA across home, clinic, and two staff. Most functions stayed put, but when they differed, follow-up tests pinned the rogue stimulus—exactly what G et al. told us to do.

Tassé et al. (2013) reviewed a decade of charts and listed the top hidden triggers clinicians actually added: restricted materials, sudden transitions, and specific social phrases. Their list turns the 1997 advice into a concrete menu.

Before you label an FA “inconclusive,” run a quick stimulus probe. Switch therapists, move rooms, add or remove a backpack, and watch one more session. This five-minute step can turn a muddy picture into a clear function and save weeks of guess-work.