Age Trends in the Allocation of Voluntary Attention in Typical Development and Autism

Background: Flexibly attending to and efficiently processing salient information in the visual environment is necessary to navigate the dynamics of social interaction. The nature by which toddlers, school-aged children, and adolescents explore complex visual scenes remains a compelling assay for these attentional and information processing capacities. We have developed a passive viewing Visual Exploration Task that consists of complex visual arrays balanced for social and nonsocial content. Past research has shown that children with autism spectrum disorders (ASD) demonstrate reduced exploratory visual behavior, increased perseverative attention and a more detail-oriented perceptual profile relative to typically-developing (TD) children. How these attentional operations and information processing strategies change over the course of childhood in both TD children and children with ASD is not yet known. 

Objectives: To examine age-related trends across childhood in the allocation of voluntary attention in TD and ASD using the Visual Exploration Task.

Methods: The eye movements of 51 children with ASD (M age, 9.29 years; range, 2.67 – 17.25 years) and 43 TD children (M age, 8.20 years; range, 2.08 – 16.17) were tracked as they passively viewed a series of 12 arrays consisting of pictures of people and objects. Dependent measures included exploration (the number of images fixated), perseveration (fixation time per image viewed) and detail orientation (the average number of fixations per image viewed).

Results: Across the entire task, all three dependent measures correlated strongly with age for both TD and ASD children. Both groups exhibited greater visual exploration with age (TD: r(43)=.77, p < .001; ASD: r(51)=.54, p < .001), less perseveration (TD: r(43)=-.47, p = .001; ASD: r(51)=-.39, p = .004) and less of a detail-orientation (TD: r(43)=-.63, p < .001; ASD: r(51)=-.39, p = .005). 

Conclusions: The presence of strong developmental trends in the data across the TD and ASD groups indicates that as children age, they demonstrate increasing attentional flexibility and processing efficiency, regardless of clinical status. Older children explore more items, exhibit fewer discreet fixations and spend less time processing the images explored. While children with ASD continue to demonstrate reduced visual exploration and increased perseverative attention relative to their TD counterparts from toddlerhood through adolescence, they nevertheless follow the normative developmental pattern of increasing visual exploration and decreasing perseveration across the course of childhood. While the slopes of the developmental effect appear similar for both the TD and the ASD groups, identifying the age at which the intercepts may differentiate remains an enduring challenge, and may potentially represent early markers for an autism diagnosis. Future directions include differentiating between flexible distribution of attention and efficiently processing information, and characterizing how these subcomponents contribute to voluntary and reflexive visual attention proper.