The impact of reference tones on the adjustment of interaural cues.

In the time-intensity trading paradigm, trading ratios are inconsistent in that they differ as a function of which cue is to be adjusted by the listener. Two explanations have been offered: First, the regression model assumes a regression to the interaural parameters of a reference tone played in alternation with the test tone to cause the phenomenon of inconsistent trading ratios. The second explanation is based on an inflated perceptual weighting of the to-be-adjusted cue. The perceptual-weight explanation has been supported by experimental results showing that the phenomenon of inconsistent trading ratios appears even in the absence of a reference tone. Those findings render regression as the sole explanation for inconsistent trading ratios implausible. The experiments presented in this paper address the question whether regression to the parameters of a reference tone plays a role if a reference tone is presented. Three experiments were conducted in which trials with and without reference tone were compared directly. Both within- and between-subject comparisons showed that a reference tone affects trading ratios and location judgments if present. Although regression cannot be the sole explanation for the phenomenon of inconsistent trading ratios it seems to play a role if a reference tone is presented.

The impact of practice on the adjustment of interaural cues in a lateralization task.

Lang and Buchner [J. Acoust. Soc. Am. 124, 3120-3131 (2008)] conducted trading experiments showing that the phenomenon of different trading ratios depending on which cue is adjusted by the listener is independent of the presentation of an explicit reference tone. Four experiments were conducted to test whether implicit reference tones during the preceding practice phase may have caused the different trading ratios. The results of Lang and Buchner were replicated, showing that an implicit reference learned during the practice phase cannot account for different trading ratios in experiments without the presentation of a reference tone.