Adjustment and discrimination measurements of the precedence effect

A simple model to summarize the precedence effect is proposed that uses a single metric to quantify the relative dominance of the initial interaural delay over the trailing interaural delay in lateralization. This model is described and then used to relate new measurements of the precedence effect made with adjustment and discrimination paradigms. In the adjustment task, subjects matched the lateral position of an acoustic pointer to the position of a composite test stimulus made up of initial and trailing binaural noise bursts. In the discrimination procedure, subjects discriminated interaural time differences in a target noise burst in the presence of another burst either trailing or preceding the target. Experimental parameters were the delay between initial and trailing stimuli and the overall level of the stimulus. The model parameters (the metric c and the variability of lateral position judgments) were estimated from the results of the matching experiment and used to predict results of the discrimination task with good success. Finally, the observed values of the metric were compared to values derived from previous studies.