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要旨:
It is generally believed that the acuity of the peripheral visual field is too poor to allow accurate object recognition and, that to be identified, most
objects need to be brought into foveal vision by using saccadic eye movements. However, most measures of form vision in the periphery have been done at
eccentricities below 10 degrees and have used relatively artificial stimuli such as letters, digits and compound Gabor patterns. Little is known about how such
data would apply in the case of more naturalistic stimuli. Here humans were required to categorize briefly flashed (28 ms) unmasked photographs of natural
scenes (39 degrees high, and 26 degrees across) on the basis of whether or not they contained an animal. The photographs appeared randomly in nine
locations across virtually the entire extent of the horizontal visual field. Accuracy was 93.3 for central vision and decreased almost linearly with increasing
eccentricity (89.8 at 13 degrees, 76.1 at 44.5 degrees and 71.2 at 57.5 degrees). Even at the most extreme eccentricity, where the images were
centred at 70.5 degrees, subjects scored 60.5 correct. No evidence was found for hemispheric specialization. This level of performance was achieved
despite the fact that the position of the image was unpredictable, ruling out the use of precued attention to target locations. The results demonstrate that even
high-level visual tasks involving object vision can be performed using the relatively coarse information provided by the peripheral retina.
