Auditory signal detection: effects of long-term practice and time on task.

Abstract

Within the context of the theory of signal detectability (TSD; Green & Swets, 1966), only a few studies report on the effects of practice and time on 'task. Green and Swets (1966, p. 399) conclude, on the basis of the studies by Gundy (1961), Lukaszewski and Elliot (1962), Swets and Sewall (1963), and Zwislocki, Maire, Feldman, and Rubin (1958), that as far as such simple signals as pure tones are concerned, any practice effect is limited to the first experimental session and consequently is not a serious concern. Gundy studied the effect of practice on the value of d I for a variety of conditions, including the presentation or withholding of previews of the signal. It appeared that the presentation of previews, which is a common procedure in TSD studies, eliminated the occurrence of practice effects observed under the condition of no previews. The experiments of Swets and Sewall showed practice effects to be dependent upon the level of motivation. They were only detectable with a low level of motivation. Using a forced-choice procedure, Lukaszewski and Elliot and Zwislocki et al. found an increase in the percentage of correct responses in the course of their experiments. With regard to time on task effects, Deaton, Tobias, and Wilkinson (1971) report a decrease in d I and an increase in fJ over the two halves of a 30-min session. Wilkinson and Seales (1978) recorded an increase in fJ and a nonsignificant decrease in d 'over the two halves of a session of 240 trials. Accordingly, there are indications of the existence of practice and time on task effects in detection tasks. The consistency, the extent, and the time course of these effects are more extensively investigated in the present study.