Reduced Language Processing Asymmetry in Non-autistic Individuals with High Levels of Autism Traits

Lindell, A. K., Notice, K., & Withers, K. (2009). Reduced language processing asymmetry in non-autistic individuals with high levels of autism traits. Laterality, 14(5), 457-472.  Retrieved at EBSCOhost.  doi:10.1080/13576500802507752

Chapter 15 in our textbook discusses cerebral asymmetry.  The two cerebral hemispheres are specialized and process information differently and think differently.  The right hemisphere involves creativity and visuo-spatial functioning.  The left hemisphere involves language, logic, and reasoning.  Autism is a disorder that is marked by social interaction impairments, which are largely due to language deficits.  In normal individuals, the left hemisphere serves as a lateralization of function for language, but in individuals with autism, it is common to find different patterns of lateralization in the cerebral hemispheres.  The purpose of this study was to see if there was a difference in hemispheric processing in individuals with high and low levels of autistic traits.  Fifty-one people, ages 18 to 24, participated in this study.  They were asked to complete the Autism-Spectrum Quotient (AQ) questionnaire as well as a lateralized lexical decision task that assessed the identification of concrete and abstract words by pressing a button to respond.  Both hemispheres process concrete words, but abstract words are not easily imaginable and are processed in only the left hemisphere.  Results of this study showed that individuals with lower AQ scores had a clearer right visual field advantage for word discrimination, which means that they showed normal left hemisphere functioning.  Individuals with higher AQ scores showed equal performance for both the left and right hemispheres, which means that individuals that are higher on the autism spectrum lack left hemisphere language dominance.  The results of this study should be predictable because it has been researched several times that people with autism have a reduced hemispheric asymmetry for language processing.  However, this study proved that this idea could also be extended to the normal population.  This finding also supports the notion of autism on a continuum, rather than a categorical diagnosis.  We all lie somewhere on this continuum, but those individuals who are at the upper end of the spectrum will experience a reduction in hemispheric asymmetry for processing language.