The advent of eye-tracking technology has allowed investigators to provide a more detailed analysis of visual inspection of socially-relevant stimuli in persons with Autism Spectrum Disorder (ASD) (e.g., Anderson et al., 2006; Klin et al., 2002; Speer et al., 2007). Such data provide a more comprehensive and dynamic depiction of social attention in ASD than observational techniques.
An additional advantage of most eye-tracking technologies is the ability to simultaneously assess pupil size (an autonomic measure) within precise regions of interest. Given appropriate control of stimulus parameters (e.g., luminance) and individual patient factors (e.g., medication use), this technology has the ability to provide a powerful non-invasive tool to examine autonomic responses in children with ASD. Such measures can be taken at very early ages and are independent of cognitive or language ability.
Task-evoked (phasic) pupillary responses have long been used as a reflection of cognitive resources or attention allocated to a particular task (Beatty & Lucero-Wagoner, 2000). In addition, tonic (baseline) pupil size is often used in clinical settings to assess neurological functioning of the autonomic nervous system (ANS).
We will present data demonstrating the use of eye-tracking technology to measure pupil size in 2-5 year old children with ASD. Pupil size provides (a) an index of ANS neural functioning, (b) a biological marker that can be used in the early detection and screening of ASD, and (c) indicates the processing and selection of stimuli such as human faces or named vocabulary items.
We have used eye-tracking technology to examine tonic pupil size in a baseline condition (Anderson & Colombo, 2009; Anderson & Colombo, under review) and phasic pupillary responses to static faces (Anderson et al., 2006) and dynamic social scenes (Anderson & Colombo, under review) in 2 – 5 year old children with ASD (compared to clinical and typical age-matched controls). Finally, pupillary responses to “known” and “unknown” receptive vocabulary targets are being investigated to evaluate their use as a tool in cognitive/language assessment.
We have found a significantly larger tonic pupil size and lower AA levels in ASD, and altered phasic pupillary responses to both static and dynamic social stimuli (Anderson et al., 2006; Anderson & Colombo, 2009; under review).
Pupillometry and eye-tracking technology provide innovative findings about cognitive and autonomic function in ASD, and can provide added value to neurological and cognitive research programs. These measures show great promise in assessing candidate measures to improve assessment, diagnosis, and screening of ASD.