Eye-head coordination during rapid gaze shifts in soccer scanning

The visual exploratory behavior involving rapid gaze shifts that supports cognitive processes is called "scanning". Scanning in soccer is a foundational behavior that enables players to explore their environment, supporting rapid and accurate situational judgments. However, since most previous studies have focused on head movements, the eye-head coordination underlying gaze shifts is insufficiently understood. This study aimed to determine the coordinated roles of eye and head movements during gaze shifts in soccer scanning.

Twenty male collegiate soccer players performed a passing task paired with video-based situational judgments while eye and head movements were recorded using an eye tracker system with a built-in gyroscope. We detected eye and head velocities and amplitudes during rapid gaze shifts.

As a result, peak eye velocity was significantly larger than peak head velocity (d = 4.09, p < 0.001). The cross-correlation (CC) between gaze and eye velocities (0.92) was significantly greater than that between gaze and head velocities (0.58). Furthermore, head contribution increased with larger gaze-shift amplitudes and under higher temporal constraints. These results indicate that gaze shifts are characterized by a predominant contribution of eye movements, while head movements provide task-dependent adjustments to the overall gaze behavior. In addition, eye and head velocities were negatively correlated (r =  - 0.60, p = 0.005), indicating individual differences in eye-head coordination tendencies.

Our findings suggest that eye movements serve as the primary effector during gaze shifts in soccer scanning, showing consistent kinematic characteristics across varying task demands. Furthermore, the head could contribute in a complementary and adaptive manner, increasing its involvement in response to movement demands or situational constraints.