Directional Bias and Bilateral Symmetry in Thumbstick Control: An Empirical Study of Hand and Target Location Effects

Thumbsticks are widely adopted input devices for gaming, virtual reality, and robot control owing to their simple and intuitive manipulation. However, the kinematic characteristics of thumbstick manipulation within their workspace remain underexplored, given the mismatch between the thumb’s anatomical movement and the device’s two-dimensional analog workspace. We conducted a within-subjects experiment in which 20 participants performed a target-selection task on a commercial gamepad with symmetrical thumbsticks, with targets arranged in two concentric arrays, inner (0.5) and outer (1.0), at eight directions. Endpoint distributions revealed systematic directional biases that varied with target location. While bilateral symmetry was preserved across most target locations, a distinct rotational shift emerged along the vertical axis: clockwise for the left hand and counterclockwise for the right hand. Endpoints at inner targets tended to exceed the 0.5 radius, and participants rated inner-target transitions as the most difficult. These results support direction-aware, cross-hand calibration for thumbsticks.