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D.A. Poggel, B. Treutwein, C. Calmanti, H. Strasburger; Increasing the temporal g(r)ain: double pulse resolution improves with smaller focus of attention . Invest. Ophthalmol. Vis. Sci. 2004;45(13):5467.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Retinal structures are believed to limit visual temporal resolution (Tyler, 1985). We investigated top–down influences on double–pulse resolution (DPR), i.e. the minimum perceivable duration of a temporal gap between two light pulses, mapped across the visual field. Methods:DPR thresholds were measured in 95 subjects (age: 10–90 years). Within a trial, eight continuous stimuli and one double–pulse target were presented. Gap duration was varied in a 9–fold interleaved, 9–afc Bayesian adaptive procedure (Treutwein & Rentschler, 1992). Thresholds were determined independently at one central, and eight peripheral locations arranged on a circle around the former. Measurements were repeated with eccentricities of 2.5°, 5°, 10°, 15°, and 20°. Results:DPR thresholds significantly and systematically increased with eccentricity of the peripheral stimuli, by ∼1.1 ms/deg on average. However, thresholds measured at the central position also increased with the enlargement of the circle, even though the central stimulus location remained identical across trials. The rate of increase with eccentricity was similar in both cases. Conclusions:An increase of DPR thresholds with eccentricity can be partially explained by the use of unscaled stimuli with regard to receptive field size. However, the increase of the central threshold indicates a reduced capacity of processing and lower temporal resolution with a larger attentional focus. Since the increase of DPR with eccentricity is similar for the central and the peripheral stimuli, we propose that this increase is largely due not to retinal characteristics but to an increased size of the focus of attention.
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