Home | Index | No Autistics Allowed: Autism Society Canada Speaks For Itself

Poster Presented at the International Meeting for Autism Research

The International Meeting for Autism Research (IMFAR) is the major international gathering of scientists involved in autism research across all scientific disciplines. In 2005, this conference was held in Boston from May 5th to 7th. The IMFAR website is here http://www.cevs.ucdavis.edu/Cofred/Public/Aca/ConfHome.cfm?confid=211

Dawson, M., Mottron, L., Jelenic, P., Soulières, I. (2005, May). Superior performance of autistics on RPM and PPVT relative to Wechsler scales provides evidence for the nature of autistic intelligence. Poster presented at the International Meeting for Autism Research, Boston, MA.

To see this poster, click here (pdf, 68k)

All authors: Pervasive developmental disorders specialized clinic, University of Montréal, Hôpital Rivière-des-Prairies, 7070 Boulevard Perras, Montréal, QC, Canada H1E 1A4

Contact: M. Dawson naacanada@yahoo.ca
Website: http://www.sentex.net/~nexus23/naa_02.html


The findings regarding significant differences in percentiles between RPM and Wechsler being in inverse directions in autistics and non-autistics are highly dependent on available norms. It appears two sets of available norms for RPM for adults suffer from contradictory problems. The 1985 norms are too old and too generous, due to the Flynn effect and the population tested. The 1993 norms are too severe, having been done in conditions that cannot preclude external help for the tested population. 

In the Dawson (2005) IMFAR poster, a clerical error (M. Dawson could not know it) resulted in entering in the statistics the 1985 rather that the 1993 adult norms. I. Soulières realized this error a few days ago. A new analysis of our previous set of data, using the 1993 norms for adults, has revealed that the difference between RPM and Wechsler percentile values, although in the same direction as in Mottron (2004) and Dawson (2005), is substantially inferior to what we announced (comparison: Wechsler > 21.4 %ile to RPM; autistics: Wechsler < 4.6 %ile to RPM). We currently have a comparison group of 19 non-autistic adults who received both RPM and Wechsler. We compared their performance to that of all available autistic participants in our database. Using the new 1993 norms, the group (autistic, non-autistic) by task (RPM, Wechsler) interaction is still significant and in the same direction as before. In the current state of our research, it is therefore still true that autistic and non-autistic children and adults perform Wechsler and RPM at an inverse level of relative performance. However, the magnitude of this effect in adults has to be re-assessed. Further work will be undertaken to clarify and supplement these results.

L. Mottron & I. Soulières
June 3, 2005


Bell, N. L., Lassiter, K.S., Matthews, T.D., and Hutchinson, M.B. (2001). Comparison of the Peabody Picture Vocabulary Test-Third Edition and Wechsler Adult Intelligence Scale-Third Edition with university students. Journal of Clinical Psychology, 57, 417-422.

Carpenter, P.A., Just, M.A., and Shell, P. (1990). What one intelligence test measures: A theoretical account of the processing in the Raven Progressive Matrices test. Psychological Review, 97, 404-31.

Courchesne, E., and Pierce, K. (2005). Why the frontal cortex in autism might be talking only to itself: local over-connectivity but long-distance disconnection. Current Opinion in Neurobiology, 15, 225-30.

Flynn, J.R. (2000). IQ gains, WISC subtests and fluid g: g theory and the relevance of Spearman's hypothesis to race. Novartis Foundation Symposium, 233, 202-216.

Lohman, D.F. (2005). The role of non-verbal ability tests in identifying academically gifted students: An aptitude perspective. Gifted Child Quarterly, 49, 111-138.

Marshalek, B., Lohman, D.F., and Snow, R.E. (1983). The complexity continuum in the radex and hierarchical models of intelligence. Intelligence, 7, 107-127.

Minshew, N.J., Sweeney, J., and Luna, B. (2002). Autism as a selective disorder of complex information processing and underdevelopment of neocortical systems. Molecular Psychiatry, 7, S14-15.

Mottron, L. (2004). IQ Matching in cognitive research with individuals with high-functioning autism: Current practices, instrument biases and recommendations. Journal of Autism and Developmental Disorders, 34, 19-27. 

Mottron, L., Dawson, M., Berthiaume, C., and Soulières, I.  (2004, May). Peaks of ability reflect G factor in individuals with autism. IMFAR presentation. Sacramento, CA. 

Newman, S.D., and Just, M.A. (2005). The neural bases of intelligence: A perspective based on functional neuroimaging. In R. Sternberg and J. Pretz, Eds., Cognition and intelligence. Cambridge, UK: Cambridge University Press.

Raven, J. (2000). The Raven's Progressive Matrices: Change and stability over culture and time. Cognitive Psychology, 41, 1-48.


Top | Comments | E-mail