Feature-based Attentional Amplitude Modulations of the Steady-state Visual Evoked Potentials Reflect Blood Oxygen Level Dependent Changes in Feature-sensitive Visual Areas.

Recent EEG studies have investigated basic principles of feature-based attention by means of frequency-tagged random dot kinematograms in which different colors are simultaneously presented at different temporal frequencies to elicit steady-state visual evoked potentials (SSVEPs). These experiments consistently showed global facilitation of the to-be-attended random dot kinematogram-a basic principle of feature-based attention. SSVEP source estimation suggested that posterior visual cortex from V1 to area hMT+/V5 is broadly activated by frequency-tagged stimuli.

Global enhancement of target color-not proactive suppression-explains attentional deployment during visual search.

The current study touches on a central debate in the area of attention: how the human brain handles distraction by salient stimuli. The idea of proactive suppression proposes a new fundamental perceptual mechanism to resolve this question, whereby attentional capture by a task-irrelevant salient distractor can be preempted through top-down inhibitory mechanisms. In this study, we replicate empirical effects underlying this claim, but show that they are better explained by an alternative mechanism, global target-feature enhancement.

Global attentional selection of visual features is not associated with selective modulation of posterior alpha-band activity.

Attending to a single feature, such as color or motion, leads to global modulation of neural processing associated with the representation of the attended features. Alpha-band modulations are hypothesized to be a marker (and even a mechanism) of the modulation of neural processing. By adopting a previously used attentional shifting paradigm, we examined whether alpha-band dynamics are linked to sustained Feature-Based-Attentional (FBA) selection.

Attentional capture is modulated by stimulus saliency in visual search as evidenced by event-related potentials and alpha oscillations.

This study used a typical four-item search display to investigate top-down control over attentional capture in an additional singleton paradigm. By manipulating target and distractor color and shape, stimulus saliency relative to the remaining items was systematically varied. One group of participants discriminated the side of a dot within a salient orange target (ST group) presented with green circles (fillers) and a green diamond distractor.

Dynamics of attentional allocation to targets and distractors during visual search.

There is much debate about the neural mechanisms that achieve suppression of salient distracting stimuli during visual search. The proactive suppression hypothesis asserts that if exposed to the same distractors repeatedly, these stimuli are actively inhibited before attention can be shifted to them. A contrasting proposal holds that attention is initially captured by salient distractors but is subsequently withdrawn.