# Gaze Behavior and Positioning of Referee Teams during Three-Point Shots in Basketball
## 1 Introduction
### Three-Person Officiating System and Distribution of Tasks during Three-Point Shots  
The Three-Person Officiating System divides basketball referees' areas of responsibility into three sections: (i) the Lead is located along the baseline, (ii) the Center stands across the court, near the free-throw line, usually on the weak-side (i.e., the side far away from the ball), (iii) the Trail is positioned on the same side of the court as the Lead, but between the players and the basket on the opposite side of the court. There are guidelines for each of these positions in order to evaluate a three-point shot, along with all other game situations in basketball (Figure 1). In case of a shot attempt, basketball referees are required to position themselves as best as possible to optimally cover their designated area of responsibility and be able to assess the shot attempt with all associated actions. The referee closest to the player taking the shot (the shooter), is responsible for signaling the shot and identifying it as a two-point or three-point shot (by raising the hand with two or three fingers pointed, respectively). The Trail and the Center officials share responsibility around the area comprising the free-throw line and the free-throw circle. The Lead only takes over the responsibility for this area in fast break situations (fast attack), where the Trail and the Center are unable to follow the fast break. In all other circumstances, the Lead's task is to observe the zone and the players in it. The referee (Trail or Center) located farthest from the shot attempt, is responsible for actions and events not involving the active ball. Referees should avoid engaging in so-called _ball watching_, i.e., tracking the ball and its trajectory with their eyes during a shot attempt. Ball watching carries the risk of referees neglecting their own areas of responsibility and fulfilling their tasks appropriately. This could also lead to rule violations going unpunished [12]. Instead of watching the ball, it is expected that referees will stay with the play until the end of an action, e.g., the referee closest to the ball should focus on the defender until the shooter has landed on his feet after taking the shot. For the other two referees, it is necessary to keep the focus off the ball because when a shot is taken that is the key moment for the players to fight for the best position in order to snatch the rebound. Focusing on the rebound after the ball hits the rim might be too late to call an obvious foul [12] (Table 1). As referees' decisions can strongly impact a game situation, and even a game's outcome [13; 14], their decision making must be at a high level [14; 15] to prevent referee teams from missing relevant aspects of game action. Therefore, the primary aim of this study was to evaluate the extent to which referees fulfil the tasks assi \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & & **Phase 1** & **Phase 2** & **Phase 3** \\ \hline Lead & - & Active matchups in the zone & \begin{tabular}{c} Players in the zone fighting \\ for a rebound position \\ \end{tabular} & \begin{tabular}{c} Rebound action \\ \end{tabular} \\ Center/Trail nearby & - & \begin{tabular}{c} Shooter and defender \\ Signaling three-point shot \\ attempt \\ \end{tabular} & - & \begin{tabular}{c} Shooter and defender \\ Shot coverage \\ \end{tabular} & - & \begin{tabular}{c} Signaling successful shot \\ Perimeter rebounds \\ \end{tabular} \\ Center/Trail far away & - & Active matchups in the zone & - & \
\begin{tabular}{c} Players in the zone \\ fighting for a rebound \\ position \\ \end{tabular} & - &
\begin{tabular}{c} Perimeter rebounds \\ Goaltending (primary) \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Responsibilities of the three referees—divided into “Lead”, “Center/Trail nearby” and “Center/Trail far away”—  
to their gaze behavior during a three-point shot in basketball. We investigated whether referees comply with their primary area of responsibility, as indicated by the referees' manual for basketball.