Subjective and objective effects of tablet's pixel density

Pixel densities are increasing rapidly. We can observe this trend in particular for mobile devices like smartphones and tablets. Previous work revealed an effect of pixel density on subjective feedback and objective performance only for low resolution cathode ray tube screens. It is unclear if this effect persists for the four times higher pixel densities of current mobile devices. Therefore, we conducted a study to compare four pixel densities with 359, 180, 120, and 90 pixels per inch. While participants performed three tasks involving images, text and videos on a tablet, we measured perceived effort, perceived visual quality, task completion time, error rate, and body pose. Our results show that the effect of the pixel density highly depends on the content. We found that only for text, the four pixel densities have clearly different perceived media qualities. Pixel density seems to have a smaller effect on perceived media quality for images and videos and we found no effect on objective measures. Results show that text should be displayed in high resolution, while this is less important for images and videos.