Abstract
There is a common distinction between endogenous attention, which refers to the volitional orienting of spatial attention according to current task goals, and exogenous attention, which is the involuntary orienting to salient events regardless of current goals. Both types of attention can facilitate the sensory processing of information at an attended location, however, how they influence visual processing and whether they affect visual-cortical processing in similar or different ways is unknown. In the present study, we sought to directly test this question by comparing event-related potentials (ERPs) and alpha activity (~10Hz oscillations) over visual cortex during the cue-target interval of a series of audiovisual attentional cueing tasks. Across two within-subject experiments including healthy male and female participants, we varied the two main dimensions over which voluntary and involuntary attention tasks typically differ: cue format (centrally vs. peripherally presented) and cue informativity (spatially predictive vs. non-predictive). Our data demonstrate that all of these cues elicit lateralized ERPs over parietal-occipital cortex and also trigger decreases in occipital alpha activity over contralateral sites with respect to the cued location. Critically, the magnitude and time courses of these neural effects differ considerably based upon cue format and informativity, mirroring the time courses of previously reported behavioral effects. While peripheral cues elicit rapid changes in visual cortex, these changes are sustained only when a cue is informative as to a future target’s location. Broadly, these data suggest that voluntary and involuntary spatial attention are supported by the same changes in visual-cortical processing, shifted in time.
Significance Statement The dichotomy between endogenous and exogenous attention is a pervasive concept in the attention literature, yet very few studies have directly compared whether and how they differ in terms of their neural effects on visual processing. Using a novel cross-modal cueing paradigm, we demonstrate that each of these types of attention elicits similar lateralized changes over visual cortex in response to the different attention cues, as evidenced in lateralized ERPs and oscillatory alpha (~10Hz) activity. Importantly, and consistent with previous behavioral results, the time course of these neural changes differs depending on cue format and cue informativity. Overall, this finding implicates changes in alpha activity and lateralized slow-waves of the ERP as universal indices of spatial attention.
