Monitoring the progress of preschool children with autism enrolled in early intervention programmes: problems in cognitive assessment.
The IQ test you pick can move a preschooler with autism 20 points up or down, so always report more than one score.
01Research in Context
What this study did
The team gave three IQ tests to the same preschoolers with autism. They used the Bayley, Merrill-Palmer, and Stanford-Binet scales. All kids took every test in random order. The goal was to see if the test brand changed the score.
No teaching happened. The study only looked at how the numbers moved.
What they found
Bayley scores were the lowest. Merrill-Palmer scores were the highest. The gap was about 20 IQ points for the same child. That swing can flip a label from delayed to average.
The authors warn that picking one test can hide or fake treatment gains.
How this fits with other research
Courchesne et al. (2019) extends this work. They show strength-informed tests give a truer picture for minimally verbal autistic preschoolers. The new tools fix the 2001 test-selection problem.
Rodgers et al. (2021) and Howlin et al. (2009) pool many EIBI studies. Both note wide IQ gains, but the meta-analyses mix different tests. Magiati et al. (2001) explains part of that noise.
Mottron (2004) finds the same trap in older kids. PPVT and Raven matrices overestimate IQ versus Wechsler scales. The pattern holds across ages: test brand shifts scores.
Why it matters
Before you write a goal or share progress, give at least two different IQ tests. Report the range, not a single number. If Bayley says 70 and Merrill-Palmer says 90, tell the team both scores. This keeps expectations real and guards against seeing phantom gains from a test switch.
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02At a glance
03Original abstract
This report examines how conclusions about the progress of preschool children enrolled in early intervention programmes may be influenced by the use of different cognitive assessment tools. As part of a longitudinal treatment outcome study, 24 children with autism aged between 27 and 58 months were each tested on the Bayley, Merrill-Palmer and Vineland scales. Their performance on each of these tests was compared. Results showed that, while scores on the different tests were highly correlated, actual test scores varied considerably, with the Bayley tending to produce the lowest IQ scores and the Merrill-Palmer the highest. These findings have important implications, as it is evident that judgements about the effects of therapy may be significantly influenced by the selection of the tests for pre- and post-treatment assessments. Possible ways of collecting, recording and reporting test data, so as to avoid spurious conclusions about treatment effects, are discussed.
Autism : the international journal of research and practice, 2001 · doi:10.1177/1362361301005004005