Mental effort and task interference in auditory attention.

Dual-task performance was examined in three experiments. The primary task was to repeat or to add one to four digits presented auditorily at a rate of 1 digit/second. This primary task was combined with three different secondary tasks in which subjects listened to a list of words either for later recognition of some of the words (Experiment 1) or for detection and a later report of a target word (Experiments 2 and 3). Different patterns of task interference were obtained. Recognition performance was sensitive to between-task variations in capacity demands but did not reflect momentary attentional demands within the primary task. Detection performance reflected both between-task and within-task variation in capacity demands of the primary task. The interference between the primary and the secondary task was mutual, with more interference when the selection-cue in the detection task was a category name than when it was the target word itself. These findings are discussed in terms of effort theory of attention and the role of attentional strategies in duai-task performance.