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Maliha Ashraf, Sophie Wuerger, Minjung Kim, Helen Saunderson, Jasna Martinović, Rafał Mantiuk; Spatio-chromatic contrast sensitivity across the life span: interactions between age and light level in high dynamic range. Journal of Vision 2020;20(11):1286. doi: https://doi.org/10.1167/jov.20.11.1286.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of our study was to investigate the difference in spatio-chromatic contrast sensitivity between younger and older colour-normal observers. We were particularly interested in how the adapting light level affected the contrast sensitivity and whether there was a differential age-related change in sensitivity.
Contrast sensitivity was measured for three chromatic directions, luminance levels from 0.02 to 7000 cd/m^2, and different stimuli sizes using 4‐AFC method on a HDR display. Stimuli were Gabor patches with fixed number of cycles and spatial frequencies of 0.5, 1, 2, 4, and 6 cpd displayed to 40 observers ranging from 21 to 74 years of age. Within each session, observers were fully adapted to the fixed background luminance.
Our main findings are: (1) Contrast sensitivity increases with background luminance up to around 200 cd/m2, then either declines in case of luminance contrast sensitivity, or becomes constant in case of chromatic contrast sensitivity; (2) The sensitivity of the younger age group (<40 y.o.a.) is higher than that for the older age group roughly by 0.3 log units. This difference is roughly constant across colour directions and light levels. Only for the achromatic contrast sensitivity, the old age group shows a relatively larger decline in sensitivity for medium to high spatial frequencies at high photopic light levels; (3) Peak sensitivity and cut-off frequency of contrast sensitivity functions show decreasing trends with age and the rate of this decrease is dependent on mean luminance.
We also collected qualitative data in focus groups, which showed that in relation to visual displays, older adults in general prefer bigger letter size and sharper edges. Both of these are consistent with altered processing at higher spatial frequencies. Older observers also tend to prefer higher contrast over saturation to an extent.
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