Feature-guided attentional capture cannot be prevented by spatial filtering.

Area of Science:

• Cognitive Neuroscience
• Visual Perception
• Attention Studies

Background:

• Feature-based control processes guide attention to objects with target features during visual search.
• It is debated whether target-matching items at irrelevant locations can be excluded from attentional selection, particularly when spatial attention is narrowly focused.

Purpose of the Study:

• To investigate if probe stimuli at irrelevant lateral locations capture attention.
• To determine if this capture occurs when targets are defined by a single feature or a feature conjunction.
• To examine the spatial scope of feature-based attentional guidance.

Main Methods:

• Electrophysiological measurement of N2pc components, an indicator of attentional target selection.
• Presentation of probe stimuli at irrelevant locations preceding visual search displays.
• Varying search conditions: feature search (color or orientation) and conjunction search (color/orientation).

Main Results:

• Reliable N2pc components were triggered by probes in both feature and conjunction search tasks.
• This capture occurred even when conjunction search required focal spatial attention.
• Similar N2pc results were observed when targets were presented at fixation without spatial uncertainty.

Conclusions:

• Rapid attentional capture by feature-matching objects cannot be prevented by top-down spatial filtering.
• Feature-based attentional guidance processes operate in a spatially global manner.
• These findings challenge the notion of spatially limited attentional selection in visual search.