Effects of Different Grip Postures on the Usability of Portrait-Mode Mobile Action Games

Abstract

The impact of different grip postures on the usability of mobile games is critical. From the perspective of Fitts’ law, this study investigates how different grip postures (one-handed use with the right thumb on the screen, cradling with the thumb on the screen, and two-handed use) affect the usability of a portrait‑mode mobile action game. Thirty participants were recruited through convenience sampling, and a one-way between-subjects design was adopted to measure task completion time for button-clicking tasks, the number of coins collected, and overall subjective usability using the System Usability Scale (SUS). The results showed that: (1) For the bottom-right button, the right thumb was close to the target in all grip postures, whereas for the top-right button the thumbs were far from the target in all grip postures; the lack of significant differences in completion time between these two buttons is consistent with Fitts’ law. (2) For the top-left button, the left thumb in the cradling posture was closer to the target, and its completion time was significantly shorter than in the one-handed use with the right thumb posture, which is consistent with Fitts’ law. (3) The lack of a clear correspondence between the bottom-left button and the theoretical predictions of Fitts’ law may be due to participants being more accustomed to horizontal movements in the lower part of the screen (regardless of grip posture), which is related to device size, interface layout, and human factors. (4) When the tappable area was extended to the entire screen, no significant differences were observed among the three grip postures, again in line with Fitts’ law. (5) SUS scores did not differ significantly among the three grip postures. These findings provide useful implications and reference for related research fields.

Keywords: Grip Postures, Fitts’ Law, Mobile Game, Interface Usability, Human Factors Related To Grip Postures

DOI: 10.54941/ahfe1008055