Michelle Dawson

The Level and Nature of Autistic Intelligence

Autistics are presumed to be characterized by cognitive impairment, and their cognitive strengths (e.g., in Block Design performance) are frequently interpreted as low-level by-products of high-level deficits, not as direct manifestations of intelligence. Recent attempts to identify the neuroanatomical and neurofunctional signature of autism have been positioned on this universal, but untested, assumption. We therefore assessed a broad sample of 38 autistic children on the preeminent test of fluid intelligence, Ravens Progressive Matrices. Their scores were, on average, 30 percentile points, and in some cases more than 70 percentile points, higher than their scores on the Wechsler scales of intelligence. Typically developing control children showed no such discrepancy, and a similar contrast was observed when a sample of autistic adults was compared with a sample of nonautistic adults. We conclude that intelligence has been underestimated in autistics.

Three Reasons Not to Believe in an Autism Epidemic

According to some lay groups, the nation is experiencing an autism epidemic—a rapid escalation in the prevalence of autism for unknown reasons. However, no sound scientific evidence indicates that the increasing number of diagnosed cases of autism arises from anything other than purposely broadened diagnostic criteria, coupled with deliberately greater public awareness and intentionally improved case finding. Why is the public perception so disconnected from the scientific evidence? In this article we review three primary sources of misunderstanding: lack of awareness about the changing diagnostic criteria, uncritical acceptance of a conclusion illogically drawn in a California-based study, and inattention to a crucial feature of the “child count” data reported annually by the U.S. Department of Education.

Local bias and local-to-global interference without global deficit: A robust finding in autism under various conditions of attention, exposure time, and visual angle

A wide variety of paradigms have shown that autistic individuals present with superior performance on visual tasks. Here, the impact of task constraints on visual hierarchical processing in autism was investigated. By employing free- and forced-choice procedures, global and local processing of Navon-type hierarchical numerals was examined in 15 autistic persons (13 males, 2 females) and a comparison group. In the free-choice condition, autistics chose global and local targets randomly, though they were faster responding to local than to global targets, regardless of visual angle and exposure duration. In contrast, the comparison group exhibited a global advantage in naming time, which was evident only for shorter exposures, as well as effects of visual angle. In the forced-choice condition, autistics presented with a more important local-to-global interference than global-to-local interference, whereas the comparison group exhibited global advantage and bidirectional interference. Overall, the autistic participants presented with atypical local-to-global interference and local advantage in incongruent conditions (where global and local targets differ), in naming time as well as accuracy. The relative insensitivity of local bias to task constraints in autistics, in comparison to nonautistic participants, indicates that local bias, with local-to-global interference, is a key and characteristic feature of autistic visual cognition and a strong candidate for the “endophenotype” of autism.

Veridical mapping in the development of exceptional autistic abilities.

Superior perception, peaks of ability, and savant skills are often observed in the autistic phenotype. The enhanced perceptual functioning model (Mottron et al., 2006a) emphasizes the increased role and autonomy of perceptual information processing in autistic cognition. Autistic abilities also involve enhanced pattern detection, which may develop through veridical mapping across isomorphic perceptual and non-perceptual structures (Mottron et al., 2009). In this paper, we elaborate veridical mapping as a specific mechanism which can explain the higher incidence of savant abilities, as well as other related phenomena, in autism. We contend that savant abilities such as hyperlexia, but also absolute pitch and synaesthesia, involve similar neurocognitive components, share the same structure and developmental course, and represent related ways by which the perceptual brain deals with objective structures under different conditions. Plausibly, these apparently different phenomena develop through a veridical mapping mechanism whereby perceptual information is coupled with homological data drawn from within or across isomorphic structures. The atypical neural connectivity characteristic of autism is consistent with a developmental predisposition to veridical mapping and the resulting high prevalence of savant abilities, absolute pitch, and synaesthesia in autism.

Learning in Autism

This chapter summarizes a range of historical, current, and emerging proposals about autistic learning, covering accounts of learning in the autism intervention research, including the applied behavior analysis framework, and accounts of autistic learning in the cognitive and savant literatures. We conclude that learning in autism is characterized both by spontaneous – sometimes exceptional – mastering of complex material and an apparent resistance to learning in conventional ways. Learning that appears to be implicit seems to be important in autism, but autistics’ implicit learning may not map directly onto non-autistics’ implicit learning or be governed by the same constraints.

Lateral glances toward moving stimuli among young children with autism: Early regulation of locally oriented perception?

Autistic adults display enhanced and locally oriented low-level perception of static visual information, but diminished perception of some types of movement. The identification of potential precursors, such as atypical perceptual processing, among very young children would be an initial step toward understanding the development of these phenomena. The purpose of this study was to provide an initial measure and interpretation of atypical visual exploratory behaviors toward inanimate objects (AVEBIOs) among young children with autism. A coding system for AVEBIOs was constructed from a corpus of 40 semistandardized assessments of autistic children. The most frequent atypical visual behavior among 15 children aged 33-73 months was lateral glance that was mostly oriented toward moving stimuli and was detected reliably by the experimenters (intraclass correlation > .90). This behavior was more common among autistic than typically developing children of similar verbal mental age and chronological age. As lateral vision is associated with the filtering of high spatial frequency (detail perception) information and the facilitation of high temporal frequencies (movement perception), its high prevalence among very young autistic children may reflect early attempts to regulate and/or optimize both excessive amounts of local information and diminished perception of movement. These findings are initial evidence for the need to consider the neural bases and development of atypical behaviors and their implications for intervention strategies.

The Level and Nature of Autistic Intelligence II: What about Asperger Syndrome?

A distinctively uneven profile of intelligence is a feature of the autistic spectrum. Within the spectrum, Asperger individuals differ from autistics in their early speech development and in being less likely to be characterized by visuospatial peaks. While different specific strengths characterize different autistic spectrum subgroups, all such peaks of ability have been interpreted as deficits: isolated, aberrant, and irreconcilable with real human intelligence. This view has recently been challenged by findings of autistic strengths in performance on Ravens Progressive Matrices (RPM), an important marker of general and fluid intelligence. We investigated whether these findings extend to Asperger syndrome, an autistic spectrum subgroup characterized by verbal peaks of ability, and whether the cognitive mechanisms underlying autistic and Asperger RPM performance differ. Thirty-two Asperger adults displayed a significant advantage on RPM over Wechsler Full-Scale and Performance scores relative to their typical controls, while in 25 Asperger children an RPM advantage was found over Wechsler Performance scores only. As previously found with autistics, Asperger children and adults achieved RPM scores at a level reflecting their Wechsler peaks of ability. Therefore, strengths in RPM performance span the autistic spectrum and imply a common mechanism advantageously applied to different facets of cognition. Autistic spectrum intelligence is atypical, but also genuine, general, and underestimated.

The level and nature of autistic intelligence III: Inspection time.

Across the autism spectrum, level of intelligence is highly dependent on the psychometric instrument used for assessment, and there are conflicting views concerning which measures best estimate autistic cognitive abilities. Inspection time is a processing speed measure associated with general intelligence in typical individuals. We therefore investigated autism spectrum performance on inspection time in relation to two different general intelligence tests. Autism spectrum individuals were divided into autistic and Asperger subgroups according to speech development history. Compared to a typical control group, mean inspection time for the autistic subgroup but not the Asperger subgroup was significantly shorter (by 31%). However, the shorter mean autistic inspection time was evident only when groups were matched on Wechsler IQ and disappeared when they were matched using Ravens Progressive Matrices. When autism spectrum abilities are compared to typical abilities, results may be influenced by speech development history as well as by the instrument used for intelligence matching.

Atypical Lateral Connectivity: A Neural Basis for Altered Visuospatial Processing in Autism

BACKGROUND Autistic perception encompasses both inferior and superior performance on different types of visuospatial tasks. Influential neurocognitive models relevant to atypical perception (i.e., weak central coherence, enhanced perceptual functioning) can, to differing degrees, account for these findings. However, the neural underpinnings mediating atypical visuospatial autistic perception have yet to be elucidated. METHODS In the present study, we used a lateral masking paradigm to assess the functional integrity of lateral interactions mediating visuospatial information processing within early visual areas of autistic (n = 18) and nonautistic (n = 15) observers. Detection thresholds were measured for centrally presented Gabor targets flanked collinearly at different distances (experiment 1) and flanked orthogonally at different contrasts (experiment 2). RESULTS Autistic and nonautistic groups showed increased target sensitivity when the distance between collinear targets and flankers was small (3 lambda) but not large (6 lambda). However, the effect of small-distance facilitation was significantly greater for the autistic group. In addition, we observed a group-specific effect of contrast: in the autistic group, target sensitivity was enhanced by low flanker contrasts of both 5% and 10% luminance difference, whereas for the nonautistic group, this effect occurred at 10% contrast only. CONCLUSIONS These findings support the idea that atypical visuospatial perception in autism may originate from altered lateral connectivity within primary visual areas, differentially affecting perception at the earliest levels of feature extraction.

Increased sensitivity to mirror symmetry in autism.

Can autistic people see the forest for the trees? Ongoing uncertainty about the integrity and role of global processing in autism gives special importance to the question of how autistic individuals group local stimulus attributes into meaningful spatial patterns. We investigated visual grouping in autism by measuring sensitivity to mirror symmetry, a highly-salient perceptual image attribute preceding object recognition. Autistic and non-autistic individuals were asked to detect mirror symmetry oriented along vertical, oblique, and horizontal axes. Both groups performed best when the axis was vertical, but across all randomly-presented axis orientations, autistics were significantly more sensitive to symmetry than non-autistics. We suggest that under some circumstances, autistic individuals can take advantage of parallel access to local and global information. In other words, autistics may sometimes see the forest and the trees, and may therefore extract from noisy environments genuine regularities which elude non-autistic observers.