Figure 1. Proximity Index method illustration.

Referent gaze data distribution (‘reference’) was created using gaze coordinates from 51 typically developing (TD) males (aged 3.48±1.29 years old). Upper row: two example frames with gaze coordinates of TD children (blue dots) used to define the ‘reference’ (delimited by contours) and gaze data from a three-year-old male with autism spectrum disorder (ASD) (whose gaze coordinates are depicted as a red circle). Hotter contour color indicates the area of higher density of distribution of gaze in the TD group, meaning that a particular area was more appealing for a higher number of TD preschoolers for the given frame; the Proximity Index value for the 3-year-old male with ASD for the frame on the left had a value of 0.39 and for the frame on the right a value of 0. Lower row: Proximity Index values for the visual exploration of the 3-year-old boy with ASD over the entire video with the mean Proximity Index value indicated by the dashed red lines.