Effect of temporal position, proportional variance, and proportional duration on decision weights in temporal pattern discrimination

Two experiments investigated how listeners allocate their attention to diff erent segments of a temporal pattern. The experiments allowed a direct test of the predictions of the Proportion of Total Duration (PTD) rule and the Component Relative Entropy (CoRE) model. Listeners had to decide whether tw o sequences of nine tones had the same or different temporal patterns (tone duration=25 ms, tone frequency=1000 Hz). A sequence's temporal pattern was determined by the time intervals between each tone's offset and the next t one's onset. On same trials, the time intervals at corresponding temporal p ositions in the two sequences were identical. On different trials, the corr esponding time intervals were randomly varied. Listener attention to differ ent temporal positions within a sequence was assessed by calculating the de cision weights at each position. The results supported the CoRE model and w ere inconsistent with the PTD rule. Manipulating the mean of the time inter vals within the sequence had no consistent effect on the pattern of weights (or on overall performance), indicating that listener attention was not af fected by either the proportion of total duration or the perceptual salienc e of a longer or shorter time interval. However, manipulating the variance of the time intervals had a significant effect: the highest weight was give n to the highest variance segment. This weighting strategy leads to better performance because higher variance segments are more diagnostic of whether the sequences are the same or different. (C) 1999 Acoustical Society of Am erica. [S0001-4966(99)02001-9].