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. Author manuscript; available in PMC: 2008 Nov 25.
Published in final edited form as: J Opt Soc Am A Opt Image Sci Vis. 2005 Jan;22(1):60–67. doi: 10.1364/josaa.22.000060

Fig. 1.

Fig. 1

Mean S-axis threshold for younger (solid circles) and older (open circles) observers at two luminance levels (5 and 30 cd/m2). Error bars are ±1 standard error of the mean (SEM). The dashed line indicates the level of the lower-contrast S-axis standard.