Distinctiveness and serial position effects in tonal sequences

The proportion-of-the-total-duration rule (Kidd & Watson, 1992) states that the detectability of a change in a component of a tonal sequence can be pr edicted by the proportional duration of the changed component relative to t he length of the sequence as a whole. A similar viewpoint relies on tempora l distinctiveness to account for primacy, recency, and other serial positio n effects in memory (Murdock, 1960; Neath, 1993a, 1993b). Such distinctiven ess models predict that an item will be remembered if it is more distinctiv e along some dimension relative to possible competitors. Three experiments explored the relation between distinctiveness and proportional duration by examining the effects of the proportion of the total duration of a tone in a sequence, serial position, and interstimulus interval (ISI) on the detect ion of a change in one component of a tonal sequence. Experiment 1 replicat ed the basic effect with relatively untrained subjects and a fixed frequenc y difference. Experiment 2 showed that distinctiveness holds for tonal sequ ences and a same/different task. Experiment 3 combined the two to show that proportional duration, ISI, and position of the changed tone all contribut e to discrimination performance. The present research combines theories tha t have been proposed in the psychophysics and memory fields and suggests th at a comprehensive principle based on relative distinctiveness may be able to account for both perceptual and memory effects.