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Takako Yoshida, Teiko Kashiwada, Naoki Kajiwara, Kenji Kitahara, Tenji Wake; Two categories of glaucoma patients tell us the contribution of peripheral vision on visual search. Journal of Vision 2008;8(6):327. doi: 10.1167/8.6.327.
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© ARVO (1962-2015); The Authors (2016-present)
Peripheral vision is believed to play an important role in detecting object for guiding visual attention and foveation for achieving higher order visual analysis, e.g., part-whole integration, or small letter recognition. To test the contribution of peripheral vision on visual search for a letter under free viewing, we tested two categories of glaucoma patients; Bjerrum scotoma patients with partial peripheral vision, and concentric construction of the visual field patients with perfect loss of peripheral vision but unaffected central vision. Subjects searched for a letter. RT and error rate were collected. The causalities between these data and patients' visual factors and display factors were tested by SEM. Both groups did not show significant difference in behavioral data, whereas they showed a clear difference in causal analysis. For the concentric construction of visual field group, retinal letter distance was the chief factor that explained these data. In contrast, for Bjerrum scotoma group, all other factors but visual acuity explained RT. Visual acuity influenced error. Our initial hypothesis was that the contrasts between these two groups should suggest the contribution of the peripheral vision on the task. We analyzed the contrast and the following causalities were significantly different: age to visual acuity, visual acuity and % intact visual field to error rate, and retinal letter size to RT. Surprisingly, most causalities that showed a difference between the patient groups were related to the error rate and only one visual factor was related to RT or the search process per se. Contrary to the idea that the peripheral vision assists in guiding our attention and central vision, these results suggest that a large contribution of peripheral vision in visual search is availability of part-whole integration of letters for collective report and visibility, and that the search process itself is not such a large factor.
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