Zobel Benjamin H, Freyman Richard L, Sanders Lisa D
Department of Psychological and Brain Sciences, University of Massachusetts, Amherst, MA, 01003, USA,
Atten Percept Psychophys. 2015 Aug;77(6):1998-2010. doi: 10.3758/s13414-015-0907-4.
The precedence effect provides a novel way to examine the role of attention in auditory object formation. When presented with two identical sounds from different locations separated by a short stimulus onset asynchrony (SOA), listeners report a single auditory object at the location of the lead sound. When the SOA is above the echo threshold, listeners report hearing two auditory objects with different locations. Event-related potential (ERP) studies have shown that the number of perceived auditory objects is reflected in an object-related negativity (ORN) 100-250 ms after onset and in a posterior late positivity (LP) 300-500 ms after onset. In the present study, we tested whether these ERP effects are modulated by attention by presenting lead/lag click pairs at and around listeners' echo thresholds, while in separate blocks the listeners (1) attended to the sounds and reported whether the lag sound was a separate source, and (2) performed a two-back visual task. When attention was directed away from the sounds, neither the ORN nor the LP observed in the attend condition was evident. Instead, unattended click pairs above the echo threshold elicited an anterior positivity 250-450 ms after onset. However, an effect resembling an ORN was found in comparing the ERPs elicited by unattended click pairs with SOAs below the attended echo threshold, indicating that the echo threshold may have been lowered when attention was directed away from the sounds. These results suggest that attention modulates early perceptual processes that are critical for auditory object formation.
优先效应为研究注意力在听觉客体形成中的作用提供了一种新方法。当呈现来自不同位置、由短刺激起始异步（SOA）隔开的两个相同声音时，听众会报告在领先声音的位置有一个单一听觉客体。当SOA高于回声阈值时，听众会报告听到两个位置不同的听觉客体。事件相关电位（ERP）研究表明，感知到的听觉客体数量在声音起始后100 - 250毫秒的客体相关负波（ORN）以及起始后300 - 500毫秒的后部晚期正波（LP）中得到反映。在本研究中，我们通过在听众回声阈值及附近呈现领先/滞后点击对来测试这些ERP效应是否受注意力调节，同时在不同的实验块中，让听众（1）专注于声音并报告滞后声音是否为独立声源，以及（2）执行一个双回溯视觉任务。当注意力从声音上转移时，在专注条件下观察到的ORN和LP均不明显。相反，高于回声阈值的未被注意的点击对在声音起始后250 - 450毫秒引发了一个前部正波。然而，在比较由SOA低于专注回声阈值的未被注意的点击对所引发的ERP时，发现了一种类似ORN的效应，这表明当注意力从声音上转移时，回声阈值可能已经降低。这些结果表明，注意力调节了对听觉客体形成至关重要的早期感知过程。
