Autism spectrum disorder (ASD) is a neurologic developmental disorder that is characterized by social communication deficits and repetitive behaviors. ASD is challenging to diagnose and track, and current techniques require interactive behavior, cognition, and language tests with a trained psychologist. An additional complication is that many of these diagnostics cannot be applied to individuals who lack verbal skills either due to their young age or due to intellectual disability. It is also challenging to track an individual over time or in response to therapy due to the inherent human subjectivity of the current diagnostic measurements, as well as to quantify ASD traits using a common measurement in both humans and animals. This technology measures a neurological biomarker of ASD that can be used as an objective diagnostic and tracking tool for ASD.