Abstract
Purpose: :
Colored filters can significantly alter the appearance of colored stimuli because they selectively absorb visible light. Laser eye protection (LEP), which is worn by military and some civilian aircrew often acts like a colored filter and can alter the appearance of displays and other colored stimuli. This can result in cockpit visual compatibility problems. This study investigated if observers could be trained to associate the names of unfiltered colors with colors that had been shifted in appearance by a filter.
Methods: :
Three observers with normal color vision were tested on a color naming (CN) task while wearing a filter that blocked short wavelengths. The color stimuli consisted of 8 hues presented on a monitor for 4 sec as text items relevant to aircraft displays (e.g. RADAR, HUD). Observers had a choice of eight color names and selected the one that best matched the color of the text. After establishing CN performance with the filter, they were then given three blocks of 40 training trials where hue names for the 8 colors were displayed in the correct color, e.g., the word "BLUE" appeared on the screen and the letters were blue although the actual appearance viewed through the colored filter might not be blue. Subjects were instructed to try to learn, for example, the "new" blue. Immediately after each training block the standard CN test was re-administered. Re-testing without further training occurred again at 2 and 7 days. Data were CN error rates and response times.
Results: :
CN performance without a filter (baseline) was near 100% correct for all 8 hues in the color set. With the filter, but before training, CN errors increased to 55-70% incorrect. After each training block, CN errors decreased and by the end of the 3rd block error rates were significantly reduced and for 2 of the 3 subjects near baseline levels. For all subjects error rates at 2 days post training remained low. At 7 days 2 subjects maintained low error rates near baseline levels but the 3rd did not. Response time (RT) results did not show the rapid gains seen for error rates. Response times, in contrast to errors, increased significantly during the first CN training block. They then gradually decreased so that at the 2 days post training test they were equivalent to or lower than those with the filter prior to training. At 7 days the trend reversed for 2 subjects who's RTs returned to the levels of the first CN training block.
Conclusions: :
Subjects were able to learn to rename a set of hues that were altered in appearance by a colored filter and to retain that ability over a few days. This may form the basis of a useful training tool to acquaint aircrew with how displays will appear when wearing LEP rather than having them learn the associations through trial and error.
Keywords: color vision • color appearance/constancy • memory