Integration of global configuration and local motion in point-light walker direction estimation.

While perceiving walking direction from biological motion integrates global and local visual cues, their specific contributions to fine-grained estimation remain unclear. Across four experiments, we manipulated global configuration and local motion in point-light walkers (PLWs) to dissect their roles. Removing global structure impaired precision, whereas inverting local motion reduced both accuracy and precision, suggesting that global form stabilizes perception, while local signals provide directional information. Critically, inverting foot-but not hand-trajectories induced a dominant reversal of perceived depth direction, while its effect on left-right discrimination was substantially weaker, as confirmed by trial-level decomposition analyses. Decomposing foot acceleration revealed that both vertical and horizontal components contribute to direction judgments; reversing either component degraded performance in distinct ways, whereas inverting both yielded substantial improvement, demonstrating a flexible compensatory mechanism-though Bayesian analyses indicated that performance did not fully return to baseline. These findings suggest that fine-grained direction estimation of PLWs is driven primarily by local foot motion and sharpened by global configuration; the visual system can flexibly integrate vertical and horizontal acceleration components of the feet, and can substantially reorganize ambiguous motion patterns through multicue synergy and dynamic compensation. These findings refine the "life-detector" hypothesis by highlighting the context-dependent, flexible nature of local cue utilization and provide new evidence for understanding how global and local information interact in biological motion perception.