Impacts of TFT-LCD polarity, font size and line space on visual performance with age-difference considerations

The purpose of the present study is to investigate older adults´ visual fatigue and performance in the use of Thin Film Transistor Liquid Crystal Display (TFT-LCD). An experiment where age (older vs. young) and display polarity (positive vs. negative) were manipulated as factors was first conducted to determine the optimal display background. In the first experiment, visual fatigue was measured by critical flicker fusion (CFF) and visual performance was measured by the searching hit rate. The results showed that the negative polarity resulted in less fatigue for CFF and searching hit rate, particularly for the older subject. A subsequent experiment with all test materials displayed in negative polarity followed where age (old vs. young), font size (12 vs. 14 points), and interline spacing (single vs. double) were designed as the factors. ANOVA found a significant interaction, which indicated that the combination of 14-point font and double interline space resulted in the best visual search performance, with the effect particularly pronounced for the older subject than for the younger counterpart. Implications for the design of TFT-LCD with age considerations were discussed in details.