Directing Attention in Time as a Function of Temporal Expectation
Attention can be directed in time as well as space. Directing attention toward the time that an event is likely to occur improves speed and accuracy of information processing. Functional neuroimaging has identified a hemispheric lateralization for attentional orienting in inferior parietal cortex, with spatial orienting lateralized to the right hemisphere and temporal orienting to the left. Indeed, the left inferior parietal cortex is activated whether temporal attention is oriented voluntarily by symbolic cues or automatically by visual motion or auditory rhythms. By contrast, exogenous shifts in temporal attention to unexpectedly early targets activate sensory regions, whereas endogenous shifts to unexpectedly late targets activate the right prefrontal cortex and Supplementary Motor Area (SMA). These activations reflect phasic bursts in activity at the moment in time to which attention has been allocated, either in anticipation of an expected event or in order to process an unexpected one, and may be mediated by a top-down biasing signal from left parietal cortex.