Chota Samson, VanRullen Rufin
Centre de Recherche Cerveau et Cognition (CerCo), CNRS, UMR5549, Université de Toulouse, Toulouse, France.
Front Neurosci. 2019 Mar 15;13:232. doi: 10.3389/fnins.2019.00232. eCollection 2019.
It has long been debated whether visual processing is, at least partially, a discrete process. Although vision appears to be a continuous stream of sensory information, sophisticated experiments reveal periodic modulations of perception and behavior. Previous work has demonstrated that the phase of endogenous neural oscillations in the 10 Hz range predicts the "lag" of the flash lag effect, a temporal visual illusion in which a static object is perceived to be lagging in time behind a moving object. Consequently, it has been proposed that the flash lag illusion could be a manifestation of a periodic, discrete sampling mechanism in the visual system. In this experiment we set out to causally test this hypothesis by entraining the visual system to a periodic 10 Hz stimulus and probing the flash lag effect (FLE) at different time points during entrainment. We hypothesized that the perceived FLE would be modulated over time, at the same frequency as the entrainer (10 Hz). A frequency analysis of the average FLE time-course indeed reveals a significant peak at 10 Hz as well as a strong phase consistency between subjects ( = 25). Our findings provide causal evidence for fluctuations in temporal perception and indicate an involvement of occipital alpha oscillations.
视觉处理是否至少部分是一个离散过程，长期以来一直存在争议。尽管视觉似乎是一连串连续的感官信息，但精密的实验揭示了感知和行为的周期性调制。先前的研究表明，10赫兹范围内的内源性神经振荡相位可预测闪光滞后效应的“滞后”，这是一种时间视觉错觉，即静止物体在时间上被感知为落后于移动物体。因此，有人提出闪光滞后错觉可能是视觉系统中周期性离散采样机制的一种表现。在本实验中，我们通过使视觉系统与周期性的10赫兹刺激同步，并在同步过程中的不同时间点探测闪光滞后效应（FLE），来对这一假设进行因果检验。我们假设，所感知到的FLE会随着时间以与同步器相同的频率（10赫兹）进行调制。对平均FLE时间进程的频率分析确实在10赫兹处揭示了一个显著峰值，并且受试者之间存在很强的相位一致性（=25）。我们的研究结果为时间感知的波动提供了因果证据，并表明枕叶阿尔法振荡参与其中。
