title: Eye Tracking Reveals Abnormal Visual Preference for Geometric Images as an Early Biomarker of an Autism Spectrum Disorder Subtype Associated With Increased Symptom Severity.
abstract: BACKGROUND
  Clinically and biologically, autism spectrum disorder (ASD) is heterogeneous. Unusual patterns of visual preference as indexed by eye tracking are hallmarks; however, whether they can be used to define an early biomarker of ASD as a whole or leveraged to define a subtype is unclear. To begin to examine this issue, large cohorts are required.
  
  
  METHODS
  A sample of 334 toddlers from six distinct groups (115 toddlers with ASD, 20 toddlers with ASD features, 57 toddlers with developmental delay, 53 toddlers with other conditions [e.g., premature birth, prenatal drug exposure], 64 toddlers with typical development, and 25 unaffected toddlers with siblings with ASD) was studied. Toddlers watched a movie containing geometric and social images. Fixation duration and number of saccades within each area of interest and validation statistics for this independent sample were computed. Next, to maximize power, data from our previous study (n = 110) were added for a total of 444 subjects. A subset of toddlers repeated the eye-tracking procedure.
  
  
  RESULTS
  As in the original study, a subset of toddlers with ASD fixated on geometric images >69% of the time. Using this cutoff, sensitivity for ASD was 21%, specificity was 98%, and positive predictive value was 86%. Toddlers with ASD who strongly preferred geometric images had 1) worse cognitive, language, and social skills relative to toddlers with ASD who strongly preferred social images and 2) fewer saccades when viewing geometric images. Unaffected siblings of ASD probands did not show evidence of heightened preference for geometric images. Test-retest reliability was good. Examination of age effects suggested that this test may not be appropriate with children >4 years old.
  
  
  CONCLUSIONS
  Enhanced visual preference for geometric repetition may be an early developmental biomarker of an ASD subtype with more severe symptoms.
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, California.. Electronic address: kpierce@ucsd.edu.
authors.forename: Karen
authors.initials: K
authors.lastname: Pierce
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, California.
authors.forename: Steven
authors.initials: S
authors.lastname: Marinero
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, California.
authors.forename: Roxana
authors.initials: R
authors.lastname: Hazin
authors.affiliation: Department of Psychiatry, University of California, San Diego, La Jolla, California.
authors.forename: Benjamin
authors.initials: B
authors.lastname: McKenna
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, California.
authors.forename: Cynthia Carter
authors.initials: CC
authors.lastname: Barnes
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, California.
authors.forename: Ajith
authors.initials: A
authors.lastname: Malige
mesh_terms: D001288:Attention; D000067877:Autism Spectrum Disorder / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D002675:Child, Preschool; D015331:Cohort Studies; D053483:Eye Movement Measurements; D005133:Eye Movements / Q000502:physiology; D005260:Female; D006801:Humans; D007223:Infant; D016014:Linear Models; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D011569:Psychiatric Status Rating Scales; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D035781:Siblings; D014796:Visual Perception
keywords: Autism spectrum disorder; Early detection; Eye gaze; Eye tracking; Geometric preference; Visual attention