Thorpe S, Fize D, Marlot C
Centre de Recherche Cerveau & Cognition, Toulouse, France.
Nature. 1996 Jun 6;381(6582):520-2. doi: 10.1038/381520a0.
How long does it take for the human visual system to process a complex natural image? Subjectively, recognition of familiar objects and scenes appears to be virtually instantaneous, but measuring this processing time experimentally has proved difficult. Behavioural measures such as reaction times can be used, but these include not only visual processing but also the time required for response execution. However, event-related potentials (ERPs) can sometimes reveal signs of neural processing well before the motor output. Here we use a go/no-go categorization task in which subjects have to decide whether a previously unseen photograph, flashed on for just 20 ms, contains an animal. ERP analysis revealed a frontal negativity specific to no-go trials that develops roughly 150 ms after stimulus onset. We conclude that the visual processing needed to perform this highly demanding task can be achieved in under 150 ms.
人类视觉系统处理一幅复杂自然图像需要多长时间？主观上，识别熟悉的物体和场景似乎几乎是瞬间完成的，但通过实验测量这个处理时间却很困难。可以使用诸如反应时间之类的行为测量方法，但这些方法不仅包括视觉处理，还包括执行反应所需的时间。然而，事件相关电位（ERP）有时可以在运动输出之前很好地揭示神经处理的迹象。在这里，我们使用了一个“是/否”分类任务，在该任务中，受试者必须判断一张仅闪现20毫秒的先前未见过的照片中是否包含动物。ERP分析揭示了一种特定于否试验的额叶负波，它在刺激开始后约150毫秒出现。我们得出结论，执行这项高要求任务所需的视觉处理可以在150毫秒内完成。
