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Effect of varying CRT refresh rate on the measurement of temporal summation

Mulholland, Pádraig J., Zlatkova, Margarita B., Redmond, Tony, Garway-Heath, David F. and Anderson, Roger S. 2015. Effect of varying CRT refresh rate on the measurement of temporal summation. Ophthalmic and Physiological Optics 35 (5) , pp. 582-590. 10.1111/opo.12227

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Abstract

Purpose To quantify the effect of cathode-tube-ray (CRT) monitor refresh rate on the measurement of the upper limit of complete temporal summation (critical duration) in the peripheral visual field of healthy observers. Methods Contrast thresholds were measured for seven achromatic spot stimuli (diameter 0.48°) of varying duration (nominal values: 10–200 ms) at an eccentricity of 8.8° along the 45°, 135°, 225° and 315° meridians of the visual field in three healthy, psychophysically experienced observers. Stimuli were presented on a CRT display with a refresh rate of 60 and 160 Hz. Contrast thresholds were expressed as contrast energy with stimulus durations being estimated using (1) the sum-of-frames (SOF) method and (2) Bridgeman's method incorporating measurements of phosphor persistence. Estimates of the critical duration were produced using iterative two-phase regression analysis. Results With stimulus duration expressed as SOF equivalent the critical duration was, on average, 10.6 ms longer with a refresh rate of 60 Hz (mean 45.7 ms, S.D. 10.1 ms) relative to 160 Hz (35.1 ms, S.D. 7.6 ms). When the Bridgeman method was used, minimal differences (1.8 ms) in critical duration values between the two refresh rates (60 Hz: 33.0 ms, S.D. 9.4 ms; 160 Hz: 31.2 ms, S.D. 7.0 ms) were observed. Identical trends were observed in all three subjects. Conclusions Psychophysical measurements of temporal summation are independent of variations in CRT refresh rate when the Bridgeman method, incorporating measured values of phosphor persistence, is used to estimate stimulus duration. This has significant implications for the specification of stimulus duration in psychophysical studies of vision employing conventional display monitors.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Optometry and Vision Sciences
Subjects: R Medicine > RE Ophthalmology
Uncontrolled Keywords: cathode-ray-tube;critical duration;refresh rate;stimulus duration;temporal summation
Additional Information: ssue published online: 24 AUG 2015
Publisher: Blackwell Publishing
ISSN: 0275-5408
Date of Acceptance: 3 June 2015
Last Modified: 04 Jun 2017 11:18
URI: http://orca.cf.ac.uk/id/eprint/76062

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