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

Abstract

Two experiments investigated how listeners allocate their attention to different 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 two 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 tone's onset. On same trials, the time intervals at corresponding temporal positions in the two sequences were identical. On different trials, the corresponding time intervals were randomly varied. Listener attention to different temporal positions within a sequence was assessed by calculating the decision weights at each position. The results supported the CoRE model and were inconsistent with the PTD rule. Manipulating the mean of the time intervals within the sequence had no consistent effect on the pattern of weights (or on overall performance), indicating that listener attention was not affected by either the proportion of total duration or the perceptual salience of a longer or shorter time interval. However, manipulating the variance of the time intervals had a significant effect: the highest weight was given 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.

Writing and overwriting short-term memory

“…The analysis consisted of drawing influence curves that show the contribution of each element to the ultimate decision and thereby measure changes in memory of items with time. The technique is similar to that employed by Sadralodabai and Sorkin (1999) to study the influence of temporal position in an auditory stream on decision weights in pattern discrimination. The first experiment gathered a baseline, the second varied the ISI, and the third varied the ITI.…”

Distinctiveness and serial position effects in tonal sequences

“…In contrast, when there was variability in the temporal envelope, the context mode was dominant. Sadralodabai and Sorkin (1999) showed that increases in the average duration of a gap in a tonal sequence have little effect on the attentional weight given to a particular tone, whereas an increase in the variance of the duration of the gap results in greater weight being applied to that tone. They explain this result using Lutfi's (1993Lutfi's ( , 1995Lutfi & Doherty, 1994) component-relativeentropy (CoRE) rule, which suggests that the critical factor in predicting discrimination is a component's relative contribution to the overall variance across all of the patterns in the experiment.…”

Molecular analysis of the effect of relative tone level on multitone pattern discrimination

“…Molecular psychophysics is an approach to this problem that focuses on the observer's decision process as it is reflected in the trial-by-trial data ͑Ahumada and Lovell, 1970;Gilkey and Robinson, 1986;Green, 1964;Watson, 1962͒. The approach has gained increasing application in recent years, particularly in studies of multitone pattern discrimination where the relative reliance or decision weight listeners give to the different tones in the stimulus is judged to be an important factor underlying performance ͑Alexander and Lutfi, 2004;Berg, 1989Berg, , 2004Berg and Green, 1990;Dai and Berg, 1992;Lutfi, 1996, 1999;Green and Berg, 1991;Lutfi, 1989Lentz and Leek, 2002;Sadralodabai and Sorkin, 1999;Stellmack and Viemeister, 2000;Stellmack, Willihnganz, Wightman, and Lutfi, 1997;Willihnganz, Stellmack, Lutfi, and Wightman, 1997͒. The techniques for estimating the weights differ in detail in these studies but are derived from the same general model taken to represent different stages of auditory processing leading to a decision ͑cf. Ahumada and Lovell, 1970;Berg, 1989Lutfi, 1989Lutfi, , 1995Richards and Zhu, 1994͒.…”