Human visual size perception results from an interaction of external sensory information and internal state. The cognitive mechanisms involved in the processing of context-dependent visual size perception have been found to be innate in nature to some extent, suggesting that visual size perception might correlate with human intrinsic brain activity. Here we recorded human resting alpha activity (8–12 Hz), which is an inverse indicator of sustained alertness. Moreover, we measured an object’s perceived size in a two-alternative forced-choice manner and the Ebbinghaus illusion magnitude which is a classic illustration of context-dependent visual size perception. The results showed that alpha activity along the ventral visual pathway, including left V1, right LOC and bilateral inferior temporal gyrus, negatively correlated with an object’s perceived size. Moreover, alpha activity in the left superior temporal gyrus positively correlated with size discrimination threshold and size illusion magnitude. The findings provide clear evidence that human visual size perception scales as a function of intrinsic alertness, with higher alertness linking to larger perceived size of objects and better performance in size discrimination and size illusion tasks, and suggest that individual variation in resting-state brain activity provides a neural explanation for individual variation in cognitive performance of normal participants.

人的视觉尺寸感知是外部感官信息和内部状态相互作用的结果。已经发现，与上下文相关的视觉尺寸知觉处理中涉及的认知机制在某种程度上是天生的，这表明视觉尺寸知觉可能与人类固有的大脑活动相关。在这里，我们记录了人类的静息阿尔法活动（8–12 Hz），这是持续警觉性的逆指标。此外，我们以两种选择的强制选择方式以及Ebbinghaus幻觉量级（是上下文相关视觉大小感知的经典例证）来测量对象的感知大小。结果显示，沿腹侧视觉通路的alpha活性，包括左V1，右LOC和双侧颞下回，与物体的感知大小负相关。而且，左上颞回中的α活性与尺寸辨别阈值和尺寸幻觉大小呈正相关。这些发现提供了明确的证据，即人类视觉大小感知是内在机敏性的函数，更高的机敏性与更大的物体感知大小有关，并且在大小辨别和大小错觉任务中表现更好，并且表明静息状态大脑活动的个体差异为正常参与者的认知表现的个体差异提供了神经学解释。