Fitts' Throughput and "Absolute" Finger Precision by Handedness, Hand, Digit and Target Width

We are motivated to understand the effects of handedness, hand, digit, and target width on human performance while pointing at touchscreen targets. Using methods suggested in literature, we report findings from a systematic study with an equal number of left- and right-handed users (N = 32) for two measures. The first measure is Fitts' throughput, which is the rate at which a human can transfer information to a device independent of their speed-accuracy tradeoff. We systematically compare the effects of handedness (left- or right-), hand (dominant or non-dominant) and digit (forefinger or thumb) on Fitts' throughput for discrete tasks. As expected, the dominant forefinger has a significantly higher throughput than the other three digits, and the dominant thumb gives significantly higher throughput than the two non-dominant digits. The second measure is the absolute precision of human "fat"fingers on touchscreens, which cannot be controlled by the speed-accuracy tradeoff. We report the effect of handedness, hand, digit and target width on the absolute precision. We found that the target width has a significant effect on the absolute precision. However, we also discovered that the current method used for measuring absolute precision leads to an overestimate. We speculate potential causes that can be verified in future research.