Task design and stimulus timing. A, Subjects were cued to report the number of events from auditory, visual, or auditory and visual streams from either the left or the right hemifield. After a short interval, either 1 or 2 flashes and/or 1 or 2 beeps were presented, simultaneously on both the left and right. Subjects were required to report how many flashes and beeps were in the stream from the attended direction while maintaining central fixation. B, Illustration of all possible trial types. The timing [i.e., whether an event occurred in Stimulus Interval (SI) 1 or 2] and direction (attended vs unattended) of all possible trial types are shown with the abbreviations used in the text to describe them. The number of stimuli (n) from the attended direction is denoted by V_n or A_n, whereas the number at the unattended location are denoted v_n or a_n. In unisensory trials only auditory or visual stimuli were presented. C, Stimulus timing.