Investigating effects of font faces and line spacing in vehicle Infotainment system on driver performance including driving distractions

Abstract

The objective of this study was to investigate the legibility of font faces and line spacings used in actual commercial in-vehicle displays by three empirical studies. A total of four fonts were selected, including three fonts from the automotive market and one font for a baseline. The three fonts called the font V, F, and T have different characteristics in their typeface style, each representing the humanist style, the geometric style, and the square grotesque style. The first experiment examined the impact of 4 types of font face on the tracking performance, distinguishing correct word among the visually similar words. The results demonstrated the font T was associated with the best tracking performance, while the font V induced poor tracking performance. Also, the results showed the secondary task arouses the cognitive workload that negatively affects performing the primary task. The second experiment asked participants to understand the messages' context and fill out the same texts' blanks. The results revealed no significant difference in the tracking performance with the font face styles and the line spacings. However, the distraction of the secondary tasks was validated with this experiment. These results demonstrated that the types of fonts or line spacings do not influence comprehending the context and tracking performance. On the other hand, the subjective preference survey demonstrated that participants preferred the font F and V, but the font C. Also, they rated the largest line spacing the best, which was 180% of the font size. Only the eye dwell time on the secondary task area was examined across the font faces and the line spacings for the last experiment. The results presented no significant differences in the eye dwell time with the font faces and the line spacings. The prior research explained these results about eye-glance behavior in driving situations, proposing that eye-glance behavior is a human's intrinsic behavior. That is, eye dwell time is not determined by the design factors, but by the humans' action of instinct. Consequently, the consideration of font faces may be utilized for the in-vehicle interface design, which required drivers to distinguish certain words among others.