Abstract
People are very precise in the discrimination of a line orientation relative to the cardinal (vertical and horizontal) axes, while their orientation discrimination sensitivity along the oblique axes is less refined. This difference in discrimination sensitivity along cardinal and oblique axes is called the “oblique effect.” Given that the oblique effect is a basic feature of visual processing with an early developmental origin, its investigation in children with Autism Spectrum Disorder (ASD) may shed light on the nature of visual sensory abnormalities frequently reported in this population. We examined line orientation sensitivity along oblique and vertical axes in a sample of 26 boys with ASD (IQ > 68) and 38 typically developing (TD) boys aged 7–15 years, as well as in a subsample of carefully IQ-matched ASD and TD participants. Children were asked to detect the direction of tilt of a high-contrast black-and-white grating relative to vertical (90°) or oblique (45°) templates. The oblique effect was reduced in children with ASD as compared to TD participants, irrespective of their IQ. This reduction was due to poor orientation sensitivity along the vertical axis in ASD children, while their ability to discriminate line orientation along the oblique axis was unaffected. We speculate that this deficit in sensitivity to vertical orientation may reflect disrupted mechanisms of early experience-dependent learning that takes place during the critical period for orientation selectivity.
Highlights
Autism spectrum disorder (ASD) is a disorder characterized by early emerging social and communication impairments, as well as rigid and repetitive patterns of behaviors and interests
The final sample was comprised of 26 Autism Spectrum Disorder (ASD) and 36 typically developing (TD) boys
The ASD and TD groups did not differ in chronological age [t(60) = 1.84, p = 0.07], but the mean IQ score was higher in the TD than in the ASD participants [t(60) = 7.04, p < 0.001]
Summary
Autism spectrum disorder (ASD) is a disorder characterized by early emerging social and communication impairments, as well as rigid and repetitive patterns of behaviors and interests. Atypical sensory processing has been observed in ASD within multiple sensory modalities including vision (Davis et al, 2006; Simmons et al, 2009; Marco et al, 2011; Ausderau et al, 2014). Recent studies have shown that even basic visual processes are affected in ASD (Kéïta et al, 2010, 2011; Koh et al, 2010; Greenaway et al, 2013; Latham et al, 2013; Weinger et al, 2014; Jachim et al, 2015; for a review, see Simmons et al, 2009). Since the low-level visual functions are unlikely to be strongly influenced by higher-order variables, e.g., social experience, those functions might more directly reflect the core neural deficits of ASD observed at the cellular or network levels.
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