How do we focus our attention?

A shadowing experiment investigated subjects' ability to focus their attention in the presence of two irrelevant messages. The subjects shadowed a binaurally presented message while attempting to ignore two monaurally heard distractors, one on each ear. In one condition, the distractors were normally spoken messages. In a second condition, the distractors were reversed speech (normal speech played backwards). In a third condition, subjects shadowed a binaural message while attempting to ignore a single binaurally presented, reversed-speech distractor. The subjects combined both locational cues and the forward/reversed cue to help them to select the appropriate message. This result implies that the discriminability of the relevant message from the background is an important factor in selection. It exerts an effect in addition to any influence of the number of groups into which attended and background messages are segregated.