Listening with a dual brain: Hemispheric asymmetry in sustained attention

Subjects listened for increments in the duration of recurrent white-noise pulses during an 80-min vigil. Critical signals for detection appeared in either a temporally regular or an irregular manner while acoustic stimulation was delivered either binaurally or monaurally to the left or to the right ear. Temporal regularity had no significant effect on performance, but performance was influenced by the input conditions and by time on task. Response times (RTs) to the detection of binaural and left-ear signals had a common origin and increased in a negatively accelerated fashion over time. By contrast, RTs to right-ear signals were relatively sluggish early in the vigil and remained stable over time. The results suggest a functional asymmetry in hemispheric organization during the maintenance of sustained attention.