A Unified Theory of Exogenous and Endogenous Attentional Control

Although diverse, theories of visual attention generally share the notion that attention is controlled by some combination of three distinct strategies: (1) exogenous cueing from locallycontrasting primitive visual features, such as abrupt onsets or color singletons (e.g., Itti & Koch, 2001); (2) endogenous gain modulation of exogenous activations, used to guide attention to task relevant features (e.g., Navalpakkam & Itti, 2005; Wolfe, 1994); and (3) endogenous prediction of likely locations of interest, based on task and scene gist (e.g., Torralba, Oliva, Catelhano, & Henderson, 2006). Because these strategies can make conflicting suggestions, theories posit arbitration and combination rules. We propose an alternative conceptualization consisting of a single unified mechanism that is controlled along two dimensions: the degree of task focus, and the spatial scale of operation. Previously proposed strategies—and their combinations—can be viewed as instances of this mechanism. Our theory offers a means of integrating data from a wide range of attentional phenomena. More importantly, the theory yields an unusual perspective on attention that places a fundamental emphasis on the role of experience and task-related knowledge.