Shifts of attention in the identification and discrimination of intensity

Subjects’ ability to resolve stimuli varying in loudness is studied by manipulating task requirements and sequential dependencies in signal presentations. In the first experiment, subjects are required both to identify and to discriminate the same set of 11 randomly presented signals. On the one hand, resolution performance is virtually unchanged under the differing task instructions. On the other hand, large effects on sensitivity are obtained in Experiments 1, 2, and 3 in both identification and discrimination tasks when sequential dependencies are manipulated. The results are interpreted in terms of a shifting attention band in the intensity dimension, as suggested by Luce, Green, and Weber (1976). Preliminary evidence that subjects can voluntarily focus the attention band on a given region of the intensity continuum is obtained.