Cognitive mechanisms, specificity and neural underpinnings of visuospatial peaks in autism.
Caron MJ, Mottron L, Berthiaume C, Dawson M.
Clinique Specialisee de l'Autisme, Hopital Riviere-des-Prairies, Montreal, Canada; Departement de Psychologie, Universite du Quebec a Montreal, Montreal, Canada.
In order to explain the cognitive and cerebral mechanisms responsible for the visuospatial peak in autism, and to document its specificity to this condition, a group of eight high-functioning individuals with autism and a visuospatial peak (HFA-P) performed a modified block-design task (BDT; subtest from Wechsler scales) at various levels of perceptual cohesiveness, as well as tasks tapping visuomotor speed, global perception, visual memory, visual search and speed of visual encoding. Their performance was compared with that of 8 autistics without a visuospatial peak (HFA-NP), 10 typically developing individuals (TD) and 8 gifted comparison participants with a visuospatial peak (TD-P). Both HFA-P and HFA-NP groups presented with diminished detrimental influence of increasing perceptual coherence compared with their BDT-matched comparison groups. Neither autistic group displayed a deficit in construction of global representations. The HFA-P group showed no differences in performance level or profile in comparison with the gifted BDT-matched [i.e. higher full-scale IQ (FSIQ)] group, apart from locally oriented perception. Diminished detrimental influence of perceptual coherence on BDT performance is both sensitive and specific to autism, and superior low-level processing interacts with locally oriented bias to produce outstanding BDT performance in a subgroup of autistic individuals. Locally oriented processing, enhanced performance in multiple tasks relying on detection of simple visual material and enhanced discrimination of first-order gratings converge towards an enhanced functioning and role of the primary visual cortex (V1) in autism. In contrast, superior or typical performance of autistics in tasks requiring global processing is inconsistent with the global-deficit-driven Weak Central Coherence hypothesis and its neurobiological magnocellular deficit counterpart.
This is just the latest of this team's work, which in my opinion represents a paradigm shift; a departure from cognitive research that has traditionally attempted (in convoluted ways) to explain away cognitive differences in autistics as the result of brain damage or dysfunction. Most of this team's findings describe, in a non-demeaning manner, how autistic cognition is different, not inferior, to that of the general population. Other examples of Dr. Mottron's work follow:
Impaired Face Processing in Autism: Fact or Artifact?
Face perception in high-functioning autistic adults: evidence for superior processing of face parts, not for a configural face-processing deficit.
Enhanced Perceptual Functioning in Autism: An Update, and Eight Principles of Autistic Perception.
Non-Algorithmic Access to Calendar Information in a Calendar Calculator with Autism.
Global-Local Visual Processing in High Functioning Children with Autism: Structural vs. Implicit Task Biases.
Can Spectro-Temporal Complexity Explain the Autistic Pattern of Performance on Auditory Tasks?
Atypical visual orienting to gaze- and arrow-cues in adults with high functioning autism.
Eyes are special but not for everyone: the case of autism.
Enhanced and diminished visuo-spatial information processing in autism depends on stimulus complexity.
Quantification judgement in high functioning autism: superior or different?
Do high functioning persons with autism present superior spatial abilities?
Locally oriented perception with intact global processing among adolescents with high-functioning autism: evidence from multiple paradigms.
A study of memory functioning in individuals with autism.
Local and global processing of music in high-functioning persons with autism: beyond central coherence?
The research I find most intriguing is that of the gap in Weschler and Raven (RPM) IQ scores in autistics. (See The Nature of Autistic Intelligence). It would appear that the gap widens the more autistic the individual is. This contradicts the old assumption that Asperger autistics have normal or superior intellectual functioning compared to classic autistics. They even have a case study of a non-verbal 15 year old autistic adolescent who scores in the 0.1 percentile in the Weschler and in the 95 percentile in the RPM. In other words, the kid is profoundly retarded according to one test and close to gifted according to the other.
Let's hope Dr. Mottron and his team continue to carry out useful non-demeaning research of this nature.