Redundancy gains for visual search after complete commissurotomy.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Visual Perception

Background:

• Investigating redundant-targets effects (RTE) in visual search provides insights into attentional mechanisms.
• Commissurotomy patients offer a unique model to study interhemispheric communication in visual processing.

Observation:

• Two patients with commissurotomy (L.B., N.G.) were assessed for RTE in visual search tasks.
• Patient L.B. lacked visual interhemispheric transfer, while N.G. showed evidence of it.
• Performance was analyzed for bilateral and within-hemifield redundant-targets conditions, considering response hand and attentional demands.

Findings:

• Patient L.B. exhibited a paradoxical enhancement of bilateral RTE compared to within-hemifield conditions.
• Patient N.G. did not show this enhancement, correlating with intact interhemispheric transfer.
• Both patients showed RTE only under high attentional demands when considering uncrossed responses.
• Enhanced gains, indicative of neural coactivation, were observed with bilateral redundant targets, particularly in the slower response hand.

Implications:

• The findings suggest that neural coactivation plays a significant role in enhancing bilateral RTE.
• This coactivation appears particularly pronounced when the slower hemisphere initiates the response.
• The study highlights the differential impact of interhemispheric transfer on visual search efficiency.