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Jia Liu, Alison Harris, Nancy Kanwisher; The M100: Face categorization begins within 100 ms of stimulus presentation. Journal of Vision 2002;2(7):611. doi: 10.1167/2.7.611.
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© ARVO (1962-2015); The Authors (2016-present)
Human visual object recognition is thought to begin within 150-170 ms of stimulus onset. Here we used magnetoencephalography (MEG) to show that recognition begins substantially earlier: by 100 ms after stimulus onset MEG responses over occipitotemporal sensors are significantly higher to faces than to nonface control stimuli. The amplitude of this “M100” response is higher when a degraded face stimulus is correctly categorized as a face than when the same stimulus is incorrectly categorized, showing that the M100 reflects not simply the low-level visual features present in the stimulus, but the perceptual experience of the subject. Furthermore, the magnitude of the M100 is not correlated with correct identification of a specific face, although the magnitude of the later face-selective M170 is. Thus, categorizing a stimulus as a face apparently begins substantially earlier than identifying a specific face. More generally, by sharply reducing current estimates of the earliest latency of stimulus categorization, our findings place powerful new empirical constraints on theories of human visual recognition.
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