Sex matters: n-back modulates emotional mismatch negativity.

This work investigates the impact of task load on irrelevant emotional voice processing between the sexes. The working memory task was manipulated by asking participants to evaluate the position of a visual stimulus (0-back) and compare the position of the current stimulus with the one or two trials before (1-back and 2-back). We recorded auditory event-related potentials while presenting the emotionally spoken syllables 'dada' and acoustically matched nonvocal sounds to healthy adults. Women, not men, showed larger amplitudes of emotional mismatch negativity (MMN), presumed to reflect preattentive auditory change detection, during the 1-back task than the 0-back and 2-back tasks. Among women only weaker emotional MMN amplitudes were associated with a higher 2-back accuracy. Neither task difficulty nor sex had any effect on MMN when responding to nonvocal sounds. Our findings suggest that there are sex differences in preattentive emotional voice processing under varying levels of task load.