“…The background events can be scheduled to occur in a temporally regular and predictable manner, such as one event every 10 s, or in a temporally unpredictable manner in which, for example, the 10 s interval could represent the mean of a range of interevent intervals. Previous research has demonstrated that performance efficiency is higher when the schedule of background events is temporally regular or synchronous than when it is temporally irregular or asynchronous (Richter, Senter, & Warm, 1981;Scerbo, Warm, Doettling, Parasuraman, & Fisk, 1987;Scerbo, Warm, & Fisk, 1986), a result termed the event asynchrony effect.…”