 were found to be wearing neckwear that was tighter than
their neck circumference.  The visual discrimination of the 22 subjects was
evaluated using a critical flicker frequency (CFF) test.  Results of the CFF
test indicated that tight neckwear significantly decreased the visual
performance of the subjects and that visual performance did not improve
immediately when tight neckwear was removed.
		-- Langan, L.M. and Watkins, S.M. "Pressure of Menswear on the
		   Neck in Relation to Visual Performance."  Human Factors 29,
		   #1 (Feb. 1987), pp. 67-71.
