Implicit guidance of attention: The priority state space framework.

Visual selective attention is the process by which we tune ourselves to the world so that, of the millions of bits per second transmitted by the retina, the information that is most important to us reaches awareness and directs action. Recently, new areas of attention research have opened up as classic models dividing attention into top-down and bottom-up systems have been challenged. In this paper, we propose a theoretical framework, the priority state space (PSS) framework, integrating sources of salience that guide visual attention according to a nested hierarchy of goals. Using the PSS framework as a scaffold, we review evidence of selected sources of implicit attentional guidance, including recent research on statistical learning, semantic associations, and motivational and affective salience. We next summarize current understanding of the underlying neural circuitry facilitating guidance of attention by specific sources of salience, including key neuromodulator systems, with an emphasis on affective salience and the noradrenergic system. Finally, we discuss evidence for common mechanisms of prioritization, including integration of sources of salience via priority maps, and introduce the concept of the PSS as a model for mapping a complex dynamic attentional landscape.