Differential diagnosis of autism spectrum disorder and attention deficit hyperactivity disorder by means of inhibitory control and 'theory of mind'.

Billstedt et al. (2011) looked at two quick lab games: a stop-signal task for inhibitory control and a false-belief story for theory of mind.

They gave both games to kids with autism, kids with ADHD, and kids with neither label.

The goal was to see if the scores could help doctors tell the two diagnoses apart.

Kids with ADHD were worse on the stop-signal game; kids with autism were worse on the false-belief stories.

The theory-of-mind gap closed in older kids, but the inhibitory gap stayed.

So inhibitory control worked for spotting ADHD at any age, while theory of mind only helped with younger children.

Harkness et al. (2025) now says parent checklists beat both lab games for telling autism or ADHD from typical development. Their huge 2025 sample updates the 2011 advice: start with rating scales, not stop-signal boxes.

Berenguer et al. (2018) adds a third group—kids with both autism and ADHD. These children show a “double-hit” of weak inhibition and weak theory of mind, so single-cutoff rules can miss them.

Sofronoff et al. (2011) and Bramham et al. (2009) find the same split in adults: ADHD equals quick-but-wrong responses; autism equals slow planning. The pattern holds across age, backing the core claim that inhibition marks ADHD.

Use a brief inhibition task when you need quick red-flag data for ADHD, but always pair it with parent scales. Skip theory-of-mind tests for teens; they even out. If a child carries both labels, plan goals for both executive skills and social cognition.