UC San Diego

Gaze following is defined as the redirection of one's visual attention to match the object of attention of another person. It is a basic mechanism resulting in joint attention, the coordination of attention between persons towards an external object. Joint attention in turn is foundational for skills such as imitation, word learning, the interpretation of novel events, and theory-of-mind, the understanding of others' beliefs, desires, and intentions. Gaze following develops within the first 18 months of age, with a gradual improvement in the discrimination of the referred target, the incorporation of eye direction cues in addition to the earlier use of head direction cues, and the appearance of gaze following to out-of-view targets. This development has been interpreted as the gradual incorporation of qualitatively different mechanisms that improve gaze following. For example, it is believed that behind this development is a transition from a simple following of cues (attentional gaze following) into an understanding of others as agents with their own focus of attention (mentalist gaze following). Others see this development as the product of a gradual introduction of different attentional mechanisms that improve spatial aspects of gaze following. This dissertation presents a new computational model of gaze following based on reinforcement learning, a biologically plausible learning algorithm. The model replicates the developmental trajectory of gaze following as measured experimentally in key studies. This unifies attentional and mentalist interpretations of gaze following into a learning account. It also offers a parsimonious, single- mechanism account of the improvement of spatial aspects of gaze following. The dissertation also explores, in the context of the gaze following model: the developmental origins of mirror neurons and their role in imitative behavior; why gaze following tends to develop less in individuals with autism spectrum disorders; and how top- down influences can be seamlessly incorporated into bottom -up visual search. A realistic virtual reality environment platform, built to test gaze following and other cognitive development phenomena, is described