The issue of whether information to which little or no attention is paid can have lasting effects is of interest to psychologists as well as educators and advertisers. Two experiments were designed to examine whether focused attention is required, whether the immediate memory task is important, or whether subjects' knowledge that repetitions are occurring is essential. Both experiments, with college students as subjects (N=30 and N=30), used a selective listening procedure involving bianural (sounds sent to both ears) presentation of two simultaneous digit series in male and female voices. In the first study, all subjects reported an awareness of the repetitions. In the second study, where only partial recall was required, 25 of the 30 subjects were aware of some repetition. The findings suggest that retention of the temporal order of events appears to require effortful attention. (JAC)