Abstract
Spatial selective attention greatly affects our processing of complex visual scenes, yet the way in which the brain selects relevant objects while suppressing irrelevant objects is still unclear. Evidence of these processes has been found using non-invasive electroencephalography (EEG). However, few studies have characterized these measures during attention to dynamic stimuli, and little is known regarding how these measures change with increased scene complexity. Here, we compared attentional modulation of the EEG N1 and alpha power (oscillations between 8–14 Hz) across three visual selective attention tasks. The tasks differed in the number of irrelevant stimuli presented, but all required sustained attention to the orientation trajectory of a lateralized stimulus. In scenes with few irrelevant stimuli, top-down control of spatial attention is associated with strong modulation of both the N1 and alpha power across parietal-occipital channels. In scenes with many irrelevant stimuli in both hemifields, however, top-down control is no longer represented by strong modulation of alpha power, and N1 amplitudes are overall weaker. These results suggest that as a scene becomes more complex, requiring suppression in both hemifields, the neural signatures of top-down control degrade, likely reflecting some limitation in EEG to represent this suppression.
Highlights
IntroductionThe external world may present us with a multitude of rapidly changing stimuli
At any given moment, the external world may present us with a multitude of rapidly changing stimuli
Obtaining non-invasive measures of spatial attention advances our understanding of how the brain parses a complex scene, and provides a potential tool for monitoring attention in real time
Summary
The external world may present us with a multitude of rapidly changing stimuli. Many studies of visual attention provide evidence for neural mechanisms that both enhance target and suppress distractor stimuli in complex scenes, but Effects of Scene Complexity on Attention very few consider these processes during attention to dynamic stimuli (but see for example Agam and Sekuler, 2007; Drew et al, 2009; Song and Nakayama, 2009; Kerr et al, 2011; Payne et al, 2013; Stormer et al, 2013; van Ede et al, 2017) Many of these studies focused on sustained attention to a single stimulus. In order to understand both attentional enhancement and attentional suppression in the presence of various configurations of dynamic distracting stimuli, we systematically manipulated scene complexity while subjects monitored a visual stimulus during three separate experiments
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