What can autism and dyslexia tell us about intelligence?

Abstract

This paper argues that understanding developmental disorders requires developing theories and models that explicitly represent the role of general intelligence in the cognitive phenotype of the disorder. In the case of autism it is argued that the low-IQ scores of people with autism are not likely to be due to a deficit in the cognitive process that is arguably the major cause of mental retardation—namely, speed of processing—but rather low IQ reflects the pervasive and cascading effects of the deficit in the information-processing module that causes autism. In the case of dyslexia, two radically different models of reading disorder (ability = disability and a modular deficit model) are likely to be influenced by the effect of general intelligence on reading performance in ways that will remain unclear without an explicit model of how general intelligence influences reading.

Acknowledgments

The author would like to thank Uta Frith for the inspiration that her work and her personality have provided over many years. The Australian Research Council has supported this work through its discovery grant to the author (DP0665616) and colleagues, Allison Fox, Corinne Reid, and Dorothy Bishop. Thanks to members of the Neurocognitive Development Unit and the BigLab for feedback.

Notes

¹Keynote address at the Australasian Human Development Association Conference, July, 2005, Perth, Western Australia.