Complexity Amplifies Expertise: Visual Search and Anticipatory Skill Adaptations in Skilled Basketball Players

Visual search is essential for effective anticipation in dynamic sports environments, yet the impact of task complexity on visual processing across expertise levels remains unclear. This study investigated visual search behavior and anticipatory performance in 25 skilled basketball players and 25 untrained male students using eye-tracking technology during simple (five or fewer visible players) and complex (more than five visible players) basketball video-based tasks. Under simple task conditions, no significant differences were found in reaction time or accuracy between groups. However, in complex tasks, skilled athletes responded significantly faster (M = 1623 ms vs. 2077 ms, p < 0.01), with fewer fixations (M = 5.47 vs. 9.63, p < 0.001) and lower fixation frequency (p < 0.001), indicating more efficient visual strategies. Machine learning analysis using a Random Forest classifier highlighted average fixation duration and fixation frequency as the most important features for group classification. These findings suggest that cognitive and perceptual expertise in athletes becomes more pronounced under high task demands, and that training programs could benefit from emphasizing gaze efficiency, particularly by reducing unnecessary fixations and optimizing fixation timing on key areas.