Multiple spotlights of attentional selection in human visual cortex.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Visual Perception

Background:

• Spatial attention enhances visual processing, often conceptualized as a "spotlight."
• Debate exists whether spatial attention is unitary or can be divided.
• Previous research lacked definitive evidence for split spatial attention.

Purpose of the Study:

• To investigate whether spatial attention can be split between discrete, non-contiguous regions.
• To provide empirical evidence for or against the unitary "spotlight" model of attention.
• To explore the neural mechanisms underlying divided spatial attention.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to monitor brain activity.
• Participants performed a visual task requiring simultaneous attention to two targets.
• Targets were briefly displayed and masked, separated by distractor stimuli.

Main Results:

• Retinotopic enhancement was observed in visual cortex representations of both attended stimuli.
• No enhanced activation was found in the cortical areas representing distractor stimuli.
• Evidence for two distinct, simultaneously active "spotlights" of attention was found within and across hemispheres.

Conclusions:

• Spatial attention is not necessarily unitary and can be divided.
• The brain can select and process multiple visual stimuli in parallel.
• These findings challenge the traditional "spotlight" metaphor and support a more flexible model of spatial attention.