Color combinations and contrast reversals with the alphanumerics of visual display units

Abstract

This dissertation reports on the legibility effects of twenty-four combinations of text and background colors on the performance of a visual search task and an address input task on a visual display unit. Eighteen females and eighteen males were each exposed to eight color combination conditions in one session of approximately two hours duration. Measures of subjects' mood state, including fatigue state, were taken at the beginning, middle, and end of trial conditions. Subjective scale ratings of each color condition were elicited from subjects immediately following each color combination trial and a final rank ordering of the tested color combinations was made by each subject. Lowest error rates occurred with black text on a light blue background. Black on blue colors had a mean error rate of .0012 errors/character which was a substantially lower rate than combinations of magenta text on green background, green on white, and white on black background (.0032 errors/character). These combinations exhibited error rates 2.7 times as great or greater than black on blue. Other favorable combinations were blue on white, red on brown, blue on black, and yellow on black. For the address input task color combinations of text on backgrounds of white on red, black on blue, blue on brown, and red on white were substantially lower in error rates than magenta on white, black on green, magenta on green, yellow on magenta, and green on white. The high error rates here were greater than or equal to two times the lower rates. Subjects were allowed to adjust contrast settings to their preferred levels to give functional measurements of color combination effects. Measures of mood state indicated a gradual increase in level of fatigue and gradually decreasing level of vigor across the experimental trials. Order effects confirmed this result with increasing order mean error rates for all treatment conditions combined across time. Fatigue was induced to provide realistic treatment conditions.