The perceptual span in Chinese reading

The perceptual span is the area of effective vision from which useful information can be obtained during a fixation in reading (Rayner & Pollatsek, 1989). McConkie and Rayner (1975, 1976; see also Rayner & Bertera, 1979; Rayner, Well & Pollatsek, 1980) demonstrated for adults that the perceptual span for English readers is asymmetric about the point of fixation, extending approximately 3-4 characters to the left and 14-15 characters to the right. Our visual field in reading can be divided into three different regions with respect to our fixation point: the foveal region, the parafoveal region, and the peripheral region. The foveal region is the area from which high acuity information is obtained and includes 2 degrees of visual angle around the point of fixation. Where 1 degree of visual angle equates to three or four letters, then six to eight letters will fall on the foveal region. The parafoveal region extends beyond this to approximately 15 to 20 characters from the point of fixation, and finally, the peripheral region includes everything in the visual field beyond the parafoveal region (see Balota & Rayner, 1991). Reading efficiency is degraded when a smaller region of text than the perceptual span is made available to readers on any particular fixation. Readers are able to extract basic visual information from the entire region of the perceptual span. This information includes word spacing information and rough word shape information. They are able to identify letters from a smaller region of the span that extends less far from the point of fixation. Finally, the region of the perceptual span in which words can be successfully identified is reduced still more with respect to its extension from the point of fixation (Rayner, Well, Pollatsek, & Bertera, 1982; McConkie & Zola, 1987; Underwood & McConkie, 1985).