UC San Diego

Selective attention is a critical cognitive capacity that enables us to navigate our information-dense world, allowing us to focus our limited processing resources on behaviorally relevant information while filtering the irrelevant. A large body of research demonstrates that selective spatial attention can be deployed both endogenously following the internal goals of an observer and exogenously in response to salient events in the environment. These findings have motivated the adoption of a dichotomy in attention between endogenous (i.e., voluntary) and exogenous (i.e., involuntary) attentional orienting. The purpose of the present dissertation is to offer a critical evaluation of the dichotomy of attention by carefully characterizing and comparing the processes involved in exogenous and endogenous attention. Utilizing psychophysics, EEG, and both cross-modal as well as uni-modal cueing paradigms in which either auditory or visual cues preceded visual targets, I offer a novel approach to evaluate this dichotomy across 3 chapters. Chapter 1 examines whether exogenous attention elicits the same changes in neural activity as endogenous attention. Chapter 2 investigates whether exogenous attention facilitates and suppresses neural processing at cued and uncued locations, respectively, as previously demonstrated in studies of endogenous attention. Finally, Chapter 3 tests whether exogenous attention operates outside of an individual’s control, as previously theorized, or whether it is possible to exercise control over this process as in endogenous attention. Altogether, the present dissertation demonstrates that there are striking similarities in the effects of exogenous and endogenous attention upon visual processing, but also important differences that distinguish each type of attention. I conclude with a brief exploration of whether this dichotomy is useful to progressing the study of attention.