Mind wandering and selective attention to the external world.

From a cognitive neuroscience perspective, the study of attention has long centered on characterizing the basic systems we have in our brains for selecting what external sensory information to channel to our higher level, capacity-limited processes in cortex. Less understood is how these attentional systems ebb and flow in their selectivity over seconds to minutes in the course of pursuing our daily activities. Toward illuminating this issue, here we review a recent series of studies we have conducted demonstrating that the degree to which our selective attention systems are engaged with the external environment is coordinated over these timescales such that they collectively engage and disengage together as a means of transiently modulating the depth of our cognitive investment in external sensory inputs. Although our studies have primarily focused on mind wandering in healthy, young participants, we suggest that people's ability to comprehensively attenuate their selective attention to the outside world plays a fundamental role in both normal human cognition and its clinical pathology.