Choice between melodies differing in complexity under divided-attention conditions.

The processing-capacity and arousal-level effect on choice between computer-generated "melodies" differing in complexity were compared in a divided-attention situation. Subjects were exposed to either aversive (97 dB, 350-Hz square wave) or mold (56 dB) auditory stimulation prior to blocks of trials involving choice between simple (4.00 bits/tone) and complex (9.17 bits/tone) melodies. Concurrently with the processing of the chosen melody on each trial, subjects either had no task at all or worked on one of four tasks that systematically differed in (a) the processing effort demanded, and (b) the likelihood of an arousal-level increase due to conceptual conflict and/or physical exertion. Measures were obtained of changes in choice and cardiac arousal due both to auditory stimulation and tasks. Results showed that the processing-capacity factors influenced choice quite independently of the arousal-level fluctuations due to tasks, and suggested that an arousal-level increase (due to stimulation), even when relevant for choice, may be mediated by a reduction in processing capacity.