Gaze Behaviors, Estimated Quiet Eye Characteristics, and Decision Making of Nonexpert Assistant Referees Judging Offside Events in Soccer

The study analyzed the gaze behavior and decision-making performance of 20 soccer assistant referees while judging offside events. Specifically, gaze behaviors, gaze entropy, and estimated quiet eye (eQE; defined as the last fixation prior to the attacker's ball pass) characteristics (i.e., location, onset, offset, and duration) were analyzed in relation to decision-making accuracy. Although a significant number of fixations were observed on the offside line, the highest viewing time corresponded to the ball carrier. The gaze behavior indicated a high distribution of fixations, as evidenced by high stationary gaze entropy (>90%). The assistant referees also distinguished offside from onside positions above chance. However, they displayed nonprolonged eQE on the offside line. As a result, no significant relationships were found between the eQE characteristics and decision-making accuracy. The study concludes that the absence of more functional gaze behaviors, specifically with longer eQE focused on the offside line, impaired the decision-making accuracy of nonexpert assistant referees in soccer.