Eye movements are not mandatorily preceded by the N2pc component.

Area of Science:

• Cognitive Neuroscience
• Visual Perception
• Human Attention

Background:

• Attentional selection in vision is typically divided into overt (eye movements) and covert (attention shifts without eye movements) mechanisms.
• A common assumption is that covert attention automatically precedes overt eye movements during visual search.
• The N2pc component is a neurophysiological marker of covert attentional orienting, but its precise relationship with overt eye movements remains unclear.

Purpose of the Study:

• To investigate the relationship between covert attentional orienting (indexed by the N2pc component) and overt eye movements during visual search.
• To determine if the N2pc component consistently precedes saccades in a visual search task where eye movements are permitted.

Main Methods:

• Concurrent measurement of covert attention using electroencephalography (EEG) to record the N2pc component.
• Simultaneous tracking of overt eye movements using eye-tracking technology.
• Participants performed a visual search task for a lateralized target stimulus, with allowed overt eye movements.

Main Results:

• The N2pc component preceded saccades when participants carefully inspected the target stimulus before initiating an eye movement.
• When participants made naturalistic eye movements during visual search, the N2pc component did not consistently precede saccades.
• These findings indicate that the N2pc component does not always precede overt eye movements in visual search.

Conclusions:

• The assumption that covert attention (N2pc) always precedes overt eye movements is not universally supported.
• Task demands, specifically the requirement for careful stimulus inspection, influence the relationship between covert attention and overt eye movements.
• This research provides new insights into the dynamic interplay between covert and overt attentional mechanisms during visual search.