Appendix 1
Mean Reaction Times for Individual Subjects
The following figures show the mean reaction time plotted against the signal luminance, for each subject
when viewing each combination of luminance and color used. The y-axis error bars correspond to one
standard deviation about the mean reaction time. The x-axis error bars correspond to one standard
deviation about the mean measured luminance. The x-axis error bars are only given for the
measurements made in the first experiment. For that study, the luminance of the signals was measured in
several different ways and the results averaged. No additional luminance measurements were made in
the third experiment, the relationship between mean measured luminance and current through the LED
established in the first experiment being used to predict the current required to achieve the desired signal
luminance in the third experiment. The three curves in each figure are power law fits through the mean
reaction times, the mean reaction times plus one standard deviation and the mean reaction time minus
one standard deviation. The power law fits through the mean reaction times plus and minus one standard
deviation have been calculated to provide a sensitivity test for the normalized equations predicting the
percentage change in reaction time (See Appendix 3).
A1-1