Static background distance modulates reaction time and interceptive timing for approaching targets in a real three-dimensional environment.

Rapid and accurate processing of approaching objects is critical for everyday activities and sports. Environmental context in three-dimensional (3D) space provides depth that may modulate visuomotor responses to motion in depth, yet its influence on rapid motor reactions and temporal prediction remains unclear. This study examined whether static background distance affects reaction time (RT) and interceptive timing for approaching targets in a real 3D environment. Fourteen participants completed RT and interceptive tasks with backgrounds positioned 0.6 m (near), 4 m (middle), and 8 m (far) from a tennis ball launcher. In the RT task, participants pressed a button immediately after ball launch, whereas in the interceptive task they judged when the ball would contact a reference plane. Egocentric distance perception was also assessed. Hierarchical Bayesian modeling showed that RTs were credibly shorter in the far than in the near condition, and timing estimates were closer to the actual arrival time in the far than in the middle condition. In addition, increases in ΔRT (near - far differences) were associated with positive shifts in timing estimates in the far condition relative to the near and middle conditions. Egocentric distance perception did not differ across backgrounds. These findings indicate that static background distance modulates both rapid and predictive visuomotor behavior in naturalistic 3D contexts and suggest that early visual motion processing may constitute a shared bottleneck for reaction and interception.