| 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 locally-contrasting primitive visual features, such as abrupt onsets or color singletons (e.g., Itti et al. [17]); (2) endogenous gain modulation of exogenous activations, used to guide attention to task relevant features (e.g., Navalpakkam and Itti [23]; Wolfe [40, 42]); and (3) endogenous prediction of likely locations of interest, based on task and scene gist (e.g., Torralba, Oliva, Castelhano, and Henderson [36]). Because these strategies can make conflicting suggestions, theories posit arbitration and combination rules. We propose a unifying conceptualization in which attention 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. Thus, this theory serves not as a replacement for existing models, but as a means of bringing them into a coherent framework. We implement this theory and demonstrate its applicability to a wide range of attentional phenomena. The model successfully yields the trends found in visual search tasks with synthetic images and makes predictions that correspond well with human eye movement data for tasks involving real world images. In addition, the theory yields an unusual perspective on attention that places a fundamental emphasis on the role of experience and task-related knowledge. |
