The use of the Leiter International Performance Scale with autistic children.

The team gave 30 autistic kids two IQ tests. One was the Leiter, a game-like kit with blocks and cards. The other was the WISC-R, the classic talk-and-point test.

Kids ranged from 4 to 16 years old. Most had little or no speech. The goal was to see if the Leiter scores matched the WISC-R scores when words were taken out.

Leiter IQ lined up almost perfectly with WISC-R Performance IQ (r = .88). It also tracked Full-Scale IQ well (.79).

The match with Verbal IQ was weak (.37). In plain words: if a child can’t talk, the Leiter still gives a solid picture of non-verbal smarts.

Alanay et al. (2007) later showed the same idea works for emotion checks. They validated the Interact Short Form for people with profound ID who also can’t speak. Both papers say: when language is gone, use a tool that watches, not listens.

Tse et al. (2021) moved the story forward. Their LSEAQ-S looks at learning, social, and emotion skills in mainstream primary students with ASD. Jason et al. (1985) gave us a cognitive snapshot; the 2021 paper gives a classroom-behavior snapshot. Together they form a fuller picture.

No clash here. The 1985 study is still the go-to for non-verbal IQ, while newer tools cover sleep, social, or adaptive domains.

If you test a minimally-verbal client tomorrow, start with the Leiter instead of fighting through a verbal IQ sub-test. You’ll get reliable data in half the time and avoid frustration. Pair those scores with today’s adaptive or social checklists to build a plan that respects both cognitive strength and daily support needs.