Abstract
Simultaneity judgments were used to measure temporal binding windows (TBW) for brief binaural events (changes in interaural time and/or level differences [ITD and ILD]) and test the hypothesis that ITD and ILD contribute to perception via separate sensory dimensions subject to binding via slow (100+ ms)—presumably cortical—mechanisms as in multisensory TBW. Stimuli were continuous low-frequency noises that included two brief shifts of either type (ITD or ILD), both of which are heard as lateral position changes. TBW for judgments within a single cue dimension were narrower for ITD (mean = 444 ms) than ILD (807 ms). TBW for judgments across cue dimensions (i.e., one ITD shift and one ILD shift) were similar to within-cue ILD (778 ms). The results contradict the original hypothesis, in that cross-cue comparisons were no slower than within-cue ILD comparisons. Rather, the wide TBW values—consistent with previous estimates of multisensory TBW—suggest slow integrative processing for both types of judgments. Narrower TBW for ITD than ILD judgments suggests important cue-specific differences in the neural mechanisms or the perceptual correlates of integration across binaural-cue dimensions.
Highlights
Simultaneity judgments were used to measure temporal binding windows (TBW) for brief binaural events and test the hypothesis that ITD and ILD contribute to perception via separate sensory dimensions subject to binding via slow (100+ ms)—presumably cortical—mechanisms as in multisensory TBW
That difference is opposite to the current results, but the overall range of TBW is consistent with Grantham’s (1986) suggestion that it takes at least 150–300 ms for the auditory system to determine the lateral position of a dynamic sound
The results provide no evidence of longer TBW duration in across-cue versus within-cue simultaneity judgments
Summary
Simultaneity judgments were used to measure temporal binding windows (TBW) for brief binaural events (changes in interaural time and/or level differences [ITD and ILD]) and test the hypothesis that ITD and ILD contribute to perception via separate sensory dimensions subject to binding via slow (100+ ms)—presumably cortical—mechanisms as in multisensory TBW. ITD and ILD are initially extracted by parallel brainstem mechanisms, but there is significant debate as to whether the cues combine Bearly^ to form a single sensory dimension of auditory space in the early auditory pathway, or instead maintain quasi-independent representations that combine Blate^—for example, via cortical mechanisms. If the latter, do ITD and ILD comprise discrete sensory dimensions subject to binding via the same principles (e.g., the TBW) that govern multisensory integration?
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