Young children (ages 24-72 month) who are HIV exposed but uninfected (CHEU) and young children who are HIV unexposed but uninfected (CHUU) undergoing a standard of care developmental evaluation will be enrolled into the study. After the completion of the developmental evaluation, research participation includes a one-time eye-tracking activity in which the child will view a series of different pictures and movies while their eye movements and pupil diameter are tracked and recorded.

Eye-tracking data will be collected using a commercially-available remote eye-tracking system (Eyelink Portable Duo). Eye movements and pupil diameter will be collected while participants view a series of developmentally appropriate pictures and movies. The eye-tracker consists of two cameras; one that monitors eye movements and a second scene camera that monitors head movements, which permits eye tracking to take place without any equipment touching the child. Children will be asked to sit in highchair or on their the lap of the caregiver and will face a computer monitor. After a sticker is applied to the forehead of the child and brief eye-movement calibration completed, next visual stimuli (i.e., pictures and videos) will be presented on a laptop computer monitor that is placed at approximately 60-80cm from the child. The eye tracking portion of the visit will last approximately 15 minutes or until the child is no longer able to attend to pictures/videos.

The composite eye-tracking biomarker score, a consolidated measure based on eye-tracking indices that predict autism outcome, will be compared to the categorical autism diagnosis (autism presence/absence). Clinical diagnosis is obtained based upon a standard clinical evaluation. The evaluation will include 1) a semi-structured caregiver(s) clinical interview to gather information about developmental history and autism symptoms and 2) a battery of standardized child clinical observational measures. The evaluation will be conducted over a one-time 2- to 3-hour clinical autism evaluation. Eye-tracking will be recorded immediately following the clinical evaluation.