When Too Much is Too little: The Impact of Increased Perceptual Load on the Focus of Attention in Typically Developing Individuals and in Individuals with Autism.
This study assesses visuospatial differences in attention in typically developing individuals and in individuals with ASD, with the goal of understanding how an increased perceptual load influences attention. The stimuli presented during the five computer tasks are in the form of social and non-social cues and will inform on how individuals with autism process these differing types of information. The research findings may contribute to the current methods for screening of ASD and in identifying ASD severity.
Principal Investigator (PI): Jason Ringo
Institution & Department: McGill University – Department of Educational & Counseling Psychology
Year(s) collaborated with SCERT on project: 2017 - 2020
Supervisor: Dr. Jacob Burack, McGill University
Co-Investigator: Dr. Lisa Jefferies, Griffith University
Results of Research Project:
Autism spectrum disorder (ASD), a complex neurodevelopmental condition that affects social communication and behavioural functioning, has been increasingly discussed as reflecting one end of a continuum that is characterized by an expansive array of traits that vary with regard to their incidence and strength. The autism continuum (Wing 1988) ranges from typically developing (TD) individuals in the population who present with lower, subclinical levels of autistic characteristics or traits to those individuals who receive an ASD diagnosis due to a more pervasive level of autistic presentation in terms of both the number and severity of the autistic features that they exhibit. This is consistent with the notions of a broad phenotypic view of autism (Bolton et al., 1994) and an underlying dimension along which all individuals vary (Baron-Cohen, 2000). This continuum perspective leads naturally to the rejection of the deficit view of autism in favor of an alternative way of processing (Burack et al., 2016).
In this study, I explore autistic traits associated with visual attention and perceptual capacity in individuals in the general population who do not meet the clinical criteria for autism. In particular, the focus is on patterns of visual field asymmetries that appear to be inconsistent with the strong visual attentional bias toward stimuli in the left visual field often observed in the general population (Verleger et al., 2009) and that are thought to be due to the lateralization of attentional control in the right cerebral hemisphere. Visual field asymmetries in the general population are more reliably observed when competing stimuli are presented simultaneously in both visual fields, resulting in competition between the hemispheres. Accordingly, a dual-stream (Holländer et al., 2005) attentional blink paradigm (AB; Raymond et al., 1992) with one stream in each visual field was used to test visual field asymmetries.
Eighty-two neurotypical university students who had never been diagnosed with autism were divided into a low (n=38) and high (n=44) autism trait group based on a cut-off score on the Autism Quotient (AQ; Baron-Cohen et al., 2001) of 17, which has been found to be the average AQ score in the general population (Ruzich et al., 2015).
A significant relationship was found between the level of autistic traits and asymmetries, as reduced visual field asymmetries were evident among the individuals high in autistic traits relative to those with lower levels of autistic traits. This finding is compelling evidence for the Broader Autism Phenotype (BAP; Piven, 2001) as variability even among subclinical levels of autistic traits are associated with some of the distinct processing features that have been cited as characteristic of persons clinically diagnosed with ASD. In particular, I relate this finding to the notion of increased perceptual processing capacity (Bayliss & Kritikos, 2011), as evidenced by the hemispheric competition associated with the dual-stream AB paradigm, among individuals with high levels of autistic traits. Increased perceptual processing capacity is thought to lead to reduced hemispheric competition and reciprocal inhibition (Kinsbourne, 1977), because the greater capacity to process perceptual information results in reduced hemispheric activation which in turn leads to decreased inhibition of the other hemisphere and subsequently in reduced or even eliminated visual field asymmetries.
This significant difference in visual field asymmetries across a population of TD college students with no clinical diagnoses of autism, points to the diversity within the general population that is consistent with the BAP and that is indicative of an overlap of characteristics among persons with clinical diagnoses of ASD and those with higher levels of autistic traits in the general population.
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