Research shows that individuals with Autism Spectrum Disorder (ASD) are superior to control subjects on conjunctive search tasks and on the Embedded Figures Test (EFT). To date, only two imaging studies have replicated the behavioral evidence for enhanced visual search, and both of these studies used versions of the EFT. Saccade generation, as well as covert and overt shifts of attention, are critical components of the visual search process; therefore, it is surprising that several studies of individuals with ASD report abnormal saccade control and slow visual orienting.

In order to more closely examine the visual system in ASD, the current study uses both eye-tracking and event-related functional magnetic resonance imaging (fMRI) to investigate the oculomotor and neurofunctional substrates of visual search. The participants in our study are adolescents diagnosed with high-functioning autism or Asperger's Syndrome and age-, gender-, and handedness-matched controls. The experiment consists of 1) a homogeneous/heterogeneous distractor search and 2) a version of the EFT. During the behavioral sessions, we obtain data on reaction time, accuracy, saccade frequency, and pupil dilation. The patented pupil dilation technique that we are using is a previously validated measure of cognitive effort. During the fMRI sessions, we measure the blood oxygenation level dependent (BOLD) response as well as the mean saccadic frequency for each trial type.

Using an EyeLink infrared eye-tracking system, we have collected preliminary data on eye movement, reaction time, and cognitive effort during visual search. We are currently analyzing these data. Eventually, the combination of performance, eye-tracking and neurofunctional data will give us a more complete picture of the visual search process in adolescents with autism.