1. 1. Although there is some debate surrounding a potential asymmetry in the pattern of movement adjustments for congruent and incongruent moving backgrounds (e.g., smaller magnitude adjustments appear to unfold for a congruent compared incongruent moving background; Proteau & Masson, 1997; for a discussion, see Roberts & Grierson, 2019), it still stands that both these contexts conceptually differ in their manipulation of the perceived limb velocity and hence changes to the movement trajectory.
2. 2. The current data are adapted from a previous study that was conducted with only the parallel moving background directions (upward vs. downward), while participants aimed at targets in upward and downward locations (see Roberts & Grierson, 2019). Thus, the previous analysis considered only the congruent and incongruent moving background directions. However, the present study additionally incorporates the perpendicular moving backgrounds in the form of rightward and leftward directions. Because of the profound energy minimization processes that contaminate downward aiming movements (i.e., increased undershooting to avoid energy-consuming overshoots against gravity), we isolated our analyses primarily to the upward aiming movements. The visuomotor processes that potentially distinguish these different aiming directions are of no theoretical value to the present study.
3. 3. The within-participant spatial variability of calibrated target recordings revealed a range of 0.57-5.72 mm and 0.86-5.39 mm for the horizontal and vertical locations, respectively.
4. Bard, C., Paillard, J., Fleury, M., Hay, L., & Larue, J. (1990). Positional versus directional control loops in visuomotor pointing. European Bulletin of Cognitive Psychology, 10(2), 145-156.
5. Beggs, W. D., & Howarth, C. I. (1972). The accuracy of aiming at a target. Some further evidence for a theory of intermittent control. Acta Psychologica, 36, 171-177. https://doi.org/10.1016/0001-6918(72)90001-7