2016 Gatlinburg Conference Poster
PS-67
Title: Quantitative Measurement of Social Motivation in Children with Autism Spectrum Disorder: Novel Task Development
Using Eye-tracking and Pupillometry
Authors: Kathryn E. Unruh, James W. Bodfish
Introduction: The Social Motivation Theory of Autism suggests that the social-specific reward deficits in ASD result from a lack of
motivation toward social information. While this theory has been influential in studying ASD-specific social deficits, few measures
have been developed to directly quantify social motivation. Eye-tracking and pupillometry can be used to study attention in ASD.
We have developed two novel tasks that incorporate these methods to quantify differential preference for and arousal to social
and nonsocial stimuli.
Methods: Our preferential viewing (eye-tracking) task measures patterns of visual attention to social and nonsocial content.
Social images (face) are paired with one of two types of objects: images of high interest to children with ASD (HAI images; e.g.
trains, electronics) and images of low interest to children with ASD (LAI images; e.g. clothing, furniture). Our pupillometry task
measures differential maintained attention (pupil dilation) over time. In this task one image is displayed at a time: social (face) or
HAI. All stimuli were controlled for luminance and complexity, counterbalanced for image position, and presented in a passive
manner for 5 seconds each, with a 2-6 second variable interstimulus interval. Participants included children diagnosed with ASD
(N = 33, mean age = 13.9 years) or typically developing (TYP; N = 41, mean age = 10.3 years); groups were matched on IQ and
gender. Gaze patterns were analyzed between array types (SOC + HAI and SOC + LAI). Pupil responses were analyzed between
stimulus types (SOC and HAI) and across 5 epochs (1000 ms each).
Results: Repeated measures ANOVA of gaze patterns showed that individuals with ASD had a longer latency to first view social
images than TYP, only when the social image was paired with an HAI nonsocial image (F = 4.3, p = .042). Additionally, individuals
with ASD spent significantly more time looking to objects [F = 15.4, p = .005], while TYP showed a preference for faces (F = 20.1, p
= .001). This suggests that our task is sensitive to group differences in social preference. Repeated measures ANOVA (Age Group
x Epoch x Stimulus) of pupil response revealed a significant 3-way interaction (F = 13.9, p = .013), indicating that pupil response
to social and nonsocial stimuli differed as a function of both age and time. This suggests that our task is sensitive to differences in
social and nonsocial information processing. Post-hoc paired-samples t-tests revealed greater pupil dilation to nonsocial images
at each time period in older children only (all ps < .05), and minimal differences between image type in younger children. This
suggests that our task may be sensitive to developmental differences in social orientation.
Discussion: These results suggest that in ASD, social information processing deficits may be relative and context-dependent,
rather than a fixed core feature of the disorder. In this model, social inattention may occur as a secondary byproduct of a positive
attention bias to nonsocial information. While gaze-tracking reveals attentional patterns, pupil responses indicate physiological
arousal; thus, these tasks may be useful markers of different underlying mechanisms contributing to social motivation deficits.
The joint use of these tasks may provide a method to tease apart the differential approach patterns seen in ASD to social and
nonsocial sources of information, while also examining differences in developmental trajectory. Furthermore, both tasks are
short (approximately 5 minutes) and passive, requiring no instructions and, therefore, may be ideal for use with both very young
children and individuals who are minimally verbal.
Supported by: NIH R01MH07342; Autism Speaks Weatherstone Fellowship 9557