Feature dependence of neural mechanisms for divided auditory attention

Abstract

Multi-talker social situations require the listener to focus attention on a single talker, as well as monitor and divide attention to additional talkers, as needed. The neural mechanisms behind how one can efficiently divide their attention has yet to be thoroughly explored. The current study investigates these neural mechanisms via electroencephalography when participants listen to competing speech and focus or divide attention. Participants were tasked either to focus and maintain attention on an initial target or to divide attention, listening to the initial target but monitoring for a potential, later “supertarget.” At the end of each trial, listeners recorded the target stimulus, defined either by location or talker identity (male or female), via a keypad. A pilot study found that focused, location-based attention modulates alpha oscillations in parietal cortex, thought to reflect inhibition of non-target locations. Here, we test the hypothesis that, during talker identity trials, attention enhances the neural representation of the target via talker identity features through enhanced beta oscillations in the frontal and middle temporal gyrus. Comparison of electroencephalography between divided and focused attention conditions suggests that using different acoustic features to focus or divide attention recruits completely different neural mechanisms.