Top-down and emotional attention in blind and sighted individuals.

Abstract

There is evidence that congenitally blind individuals possess superior auditory perceptual skills compared to sighted people. However, relatively little is known about the auditory-specific cortical correlates of spatial attention in the blind and how task-irrelevant emotional stimulus features could further modulate such neural processes. This study tested blind and sighted participants in a challenging auditory discrimination task. All participants were blindfolded and seated between loudspeakers at 45-degree angles, while pseudowords were randomly presented. The task was to identify target sounds from either the left or the right speaker while ignoring nontarget stimuli, the irrelevant loudspeaker, and irrelevant speaker identity. Emotional valence-neutral, happy, fearful, threatening-of pseudowords was task-irrelevant, focusing solely on syllable detection. Our focus was on measuring the moment-to-moment deployment of auditory-selective attention. This was achieved using the lateralized N2ac event-related potential component characterised by greater negativity at anterior electrodes on the side contralateral to an attended auditory stimulus and observed 75 to 250 ms after stimulus onset. We observed that blind individuals showed better behavioural performance and reduced N2ac amplitudes than sighted individuals. Furthermore, for both groups, N2ac amplitudes were increased for the target compared to nontarget stimuli and stimuli appearing at spatially relevant versus irrelevant locations. Our study highlights the superiority of auditory processing capabilities in blind individuals. The results also highlight the N2ac component's sensitivity to top-down attentional engagement and emotional attention, offering new insights into how blind and sighted individuals process auditory information.