The Early Development of Visual Attentional Mechanisms in Autism Spectrum Disorder

Attention plays a fundamental role in shaping cognitive development. What we attend to and what we ignore alters our visual experience of the world. Atypical attention has long been implicated in Autism Spectrum Disorder (ASD) yet our understanding of the early development of this ability has been limited by methodological factors. The aim of this thesis was to address the “toddler gap” in the literature by developing novel measures of attention that are ideal for use with toddlers, do not require verbal instructions, and can be easily scaled up or down for older or younger children. A series of three eye-tracking experiments are presented which explore visual attentional mechanisms in toddlers with ASD and age-matched typically developing controls. Experiment 1 and Experiment 2 examined selective attention to novel task-irrelevant stimuli during visual search. Toddlers with ASD demonstrated typical attentional capture when the task-irrelevant stimulus was defined by a novel onset, yet demonstrated atypically reduced attentional capture when the task-irrelevant stimulus was defined by a novel color. Experiment 3 examined attentional set-shifting in the context of visual search. No evidence of impaired set-shifting was found in toddlers with ASD. Together, findings provide important insights into the development of attentional mechanisms during the toddler period in ASD and in typical development