Sight and sound out of synch: fragmentation and renormalisation of audiovisual integration and subjective timing.
Sight and sound out of synch: fragmentation and renormalisation of audiovisual integration and subjective timing.
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DOI：
10.1016/j.cortex.2013.03.006
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发表时间：
2013-11
期刊：
影响因子：
3.6
通讯作者：
Driver, Jon
中科院分区：
文献类型：
--
作者：
Freeman, Elliot D.;Ipser, Alberta;Palmbaha, Austra;Paunoiu, Diana;Brown, Peter;Lambert, Christian;Leff, Alex;Driver, Jon
一个人说话或一个球弹跳的视觉和声音似乎是同时发生的，但它们对应的神经信号随着时间的推移而传播，因为它们到达不同的多感官大脑部位。主观计时与神经计时的关系仍然是一个基本的神经科学和哲学难题。一个占主导地位的假设是，时间的连贯性是通过感官的重复或重新校准异步脑事件。通过估计受试者群体的主观视听时间，很容易证实这一假设，不同测量和刺激的主观视听时间平均相似，并且大致真实。但很少有研究在这些措施中检查正常和病理性的个体差异。病例PH，脑桥和基底神经节病变，在看到人们的嘴唇移动之前听到他们说话。时间顺序判断（TOJ）证实了这一点：声音必须滞后嘴唇运动（延迟0.200毫秒）才能与PH同步。奇怪的是，声音必须领先嘴唇（也延迟0.200毫秒）才能最大化麦格克错觉（视听语音整合的一种衡量标准）。因此，平均而言，在这些措施中，PH的时机仍然是真实的。与之匹配的对照组参与者也表现出类似的差异。实际上，TOJ和McGurk计时的正常个体差异呈负相关：需要听觉滞后的受试者需要听觉领先的主观灵敏度，反之亦然。这就是所谓的流弹错觉。这种令人惊讶的对抗似乎与良好的感官刺激相反，但任务的平均时间仍然接近真实。我们的研究结果揭示了显着的不统一的视听时间内和之间的主题。为了解释这一点，我们提出，视听信号在不同的大脑机制的时间被认为是相对于跨机制的平均时间。这种重新正常化充分解释了PH和健康参与者不同的时间估计之间奇怪的对抗关系，以及他们如何仍然能够正确地感知外部事件的时间。
The sight and sound of a person speaking or a ball bouncing may seem simultaneous, but their corresponding neural signals are spread out over time as they arrive at different multisensory brain sites. How subjective timing relates to such neural timing remains a fundamental neuroscientific and philosophical puzzle. A dominant assumption is that temporal coherence is achieved by sensory resynchronisation or recalibration across asynchronous brain events. This assumption is easily confirmed by estimating subjective audiovisual timing for groups of subjects, which is on average similar across different measures and stimuli, and approximately veridical. But few studies have examined normal and pathological individual differences in such measures. Case PH, with lesions in pons and basal ganglia, hears people speak before seeing their lips move. Temporal order judgements (TOJs) confirmed this: voices had to lag lip-movements (by ∼200 msec) to seem synchronous to PH. Curiously, voices had to lead lips (also by ∼200 msec) to maximise the McGurk illusion (a measure of audiovisual speech integration). On average across these measures, PH's timing was therefore still veridical. Age-matched control participants showed similar discrepancies. Indeed, normal individual differences in TOJ and McGurk timing correlated negatively: subjects needing an auditory lag for subjective simultaneity needed an auditory lead for maximal McGurk, and vice versa. This generalised to the Stream–Bounce illusion. Such surprising antagonism seems opposed to good sensory resynchronisation, yet average timing across tasks was still near-veridical. Our findings reveal remarkable disunity of audiovisual timing within and between subjects. To explain this we propose that the timing of audiovisual signals within different brain mechanisms is perceived relative to the average timing across mechanisms. Such renormalisation fully explains the curious antagonistic relationship between disparate timing estimates in PH and healthy participants, and how they can still perceive the timing of external events correctly, on average.
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