Department of Speech-Language-Hearing Sciences, University of Minnesota, 164 Pillsbury Drive SE, Minneapolis, Minnesota 55455, USA.
Waisman Center, University of Wisconsin-Madison, 1500 Highland Avenue, Madison, Wisconsin 53705, USA.
J Acoust Soc Am. 2019 Feb;145(2):676. doi: 10.1121/1.5088591.
Accurate perception of binaural cues is essential for left-right sound localization. Much literature focuses on threshold measures of perceptual acuity and accuracy. This study focused on supra-threshold perception using an anticipatory eye movement (AEM) paradigm designed to capture subtle aspects of perception that might not emerge in behavioral-motor responses, such as the accumulation of certainty, and rapid revisions in decision-making. Participants heard interaural timing differences (ITDs) or interaural level differences in correlated or uncorrelated narrowband noises, respectively. A cartoon ball moved behind an occluder and then emerged from the left or right side, consistent with the binaural cue. Participants anticipated the correct answer (before it appeared) by looking where the ball would emerge. Results showed quicker and more steadfast gaze fixations for stimuli with larger cue magnitudes. More difficult stimuli elicited a wider distribution of saccade times and greater number of corrective saccades before final judgment, implying perceptual uncertainty or competition. Cue levels above threshold elicited some wrong-way saccades that were quickly corrected. Saccades to ITDs were earlier and more reliable for low-frequency noises. The AEM paradigm reveals the time course of uncertainty and changes in perceptual decision-making for supra-threshold binaural stimuli even when behavioral responses are consistently correct.
双耳线索的准确感知对于左右声音定位至关重要。大量文献专注于感知敏锐度和准确性的阈值测量。本研究使用预期眼动 (AEM) 范式关注超阈值感知，旨在捕捉可能不会在行为-运动反应中出现的细微感知方面，例如确定性的积累和决策的快速修正。参与者分别听到相关或不相关的窄带噪声中的时间差 (ITD) 或强度差。一个卡通球在一个遮挡物后面移动，然后从左侧或右侧出现，与双耳线索一致。参与者通过注视球将出现的位置来预测正确答案（在答案出现之前）。结果表明，对于具有较大线索幅度的刺激，注视时间更快且更稳定。更困难的刺激在最终判断之前会引起扫视时间分布更广和更多的校正扫视，这意味着感知不确定性或竞争。阈值以上的线索会引起一些错误方向的扫视，这些扫视会很快得到纠正。对于低频噪声，ITD 的扫视时间更早且更可靠。即使行为反应始终正确，AEM 范式也揭示了超阈值双耳刺激下不确定性的时间进程和感知决策的变化。
