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J Cogn Neurosci. 2001 Feb 15;13(2):171-80.

A limit to the speed of processing in ultra-rapid visual categorization of novel natural scenes.

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Centre de Recherche Cerveau and Cognition (UMR 5549, CNRS-UPS), Faculté de Médecine de Rangueil, Toulouse, France.


The processing required to decide whether a briefly flashed natural scene contains an animal can be achieved in 150 msec (Thorpe, Fize, & Marlot, 1996). Here we report that extensive training with a subset of photographs over a 3-week period failed to increase the speed of the processing underlying such Rapid Visual Categorizations: Completely novel scenes could be categorized just as fast as highly familiar ones. Such data imply that the visual system processes new stimuli at a speed and with a number of stages that cannot be compressed. This rapid processing mode was seen with a wide range of visual complex images, challenging the idea that short reaction times can only be seen with simple visual stimuli and implying that highly automatic feed-forward mechanisms underlie a far greater proportion of the sophisticated image analysis needed for everyday vision than is generally assumed.

[Indexed for MEDLINE]

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