Participants viewed a spot of light in the center of a screen. A light then appeared in the left or right visual field and participants were instructed to look away from the stimulus. Antisaccade here is measured as the proportion of trials in which the participant initially looked toward the spot of light, rather than away from it. Antisaccade eye movement has long been a strong candidate endophenotype for schizophrenia, replicated in dozens of studies over recent decades (Radant et al. 2010; Leonard et al. 2013). Antisaccade eye tracking error is highly heritable (Vaidyanathan et al. 2014b), present in first-degree relatives of individuals with schizophrenia, and co-segregates within families (Calkins et al. 2004; Radant et al. 2010).
