Exploring What’s Missing: What Do Target Absent Trials Reveal About Autism Search Superiority?

Abstract

We used eye-tracking to investigate the roles of enhanced discrimination and peripheral selection in superior visual search in autism spectrum disorder (ASD). Children with ASD were faster at visual search than their typically developing peers. However, group differences in performance and eye-movements did not vary with the level of difficulty of discrimination or selection. Rather, consistent with prior ASD research, group differences were mainly the effect of faster performance on target-absent trials. Eye-tracking revealed a lack of left-visual-field search asymmetry in ASD, which may confer an additional advantage when the target is absent. Lastly, ASD symptomatology was positively associated with search superiority, the mechanisms of which may shed light on the atypical brain organization that underlies social-communicative impairment in ASD.

Effect size of search superiority in autism spectrum disorder

“…One study used the Autism Spectrum Quotient to screen participants, with a cut‐off of < 25 for the control group to ensure that undiagnosed or subclinical ASD would not affect the results. Overall there was some diversity in the manner in which individuals with ASD were confirmed with some studies relying on a prior diagnosis made by either a clinical psychologist 3,46 or psychiatrist or simply ‘clinicians’ . However, for the majority at least one of the study authors confirmed the diagnosis within the study centre using the Autism Diagnostic Observational Schedule, Diagnostic and Statistical Manual IV or Autism Diagnostic Interview‐Revised …”

“…Therefore, all participants in the ASD groups received confirmation of the diagnosis of ASD, hence minimising the potential for selection bias within this population. Conversely, only four studies included a screening for ASD traits within the typically developed comparison group, creating a potential for selection bias in the other 11 studies, as participants in the comparison group may have exhibited some ASD traits. These studies were therefore graded as having moderate risk of selection bias.…”

“…Ten of the 15 studies used participants aged younger than 20 with the remaining being conducted on adult participants ages 18–58 years. Joseph et al, Keehn and Joseph had age ranges of 8.5–19.25 and 9.0–20.0 years respectively, including both children and young adults. The oldest participants included were in the study of Constable et al with an age range of 20–58 years.…”

“…The visual search target stimuli differed greatly between studies, with six studies using letters with colour defining the target, three using the same colour but a different letter as the feature and two used circles and ellipses as the target, four utilised differently orientated shapes or letters and one adopted different‐shaped clown figures for children. These differences between target and distractors would not inherently mask the performance of individuals; however, most studies did not adjust for discrimination thresholds between target and distractor for the individuals except one …”

A Magnetic Resonance Spectroscopy Study of Superior Visual Search Abilities in Children with Autism Spectrum Disorder

“…One particular strength, performance on visual search tasks (VSTs), which require participants to locate a target item embedded within an array of distractors, has been shown in infants at elevated risk for ASD [i.e., infants with an older sibling with ASD; Gliga et al, 2015], as well as toddlers, school-aged children, adolescents, and adults diagnosed with ASD [Kaldy, Giserman, Carter, & Blaser, 2016]. Furthermore, faster, more efficient search abilities are associated with higher levels of ASD symptomatology [Gliga et al, 2015;Joseph, Keehn, Connolly, Wolfe, & Horowitz, 2009;Keehn & Joseph, 2016;Keehn, Shih, Brenner, Townsend, & Müller, 2013], suggesting that nonsocial attentional processes, and the differences in brain function that these behaviors reflect, may be of etiological significance in the development of ASD.…”