Putting performance bias to the front-lower side of the hole on steep slopes: Differences in strategies and movements between professional and amateur golfers

Abstract

When playing on an sloped golf course, the ball often misses the hole to the front-lower side, which is also referred to as the "amateur side." This can be attributed to the difficulty in perceiving the green slope and choosing the appropriate launch direction and ball speed, especially for amateurs. The study had three main objectives. The first was to examine whether a front-down bias toward the hole could be experimentally observed in golfers' putting. Second, to measure golfers' aims and movements to determine why golfers, especially amateurs, putt poorly on steep slopes. Third, to investigate using a miniature platform how golfers recognized the steepness of the slopes and the relationship between their aim and their slope recognition. Twelve professionals and twelve intermediate amateurs were asked to perform in the 1- and 3-degree conditions (left-to-right line) at a distance of 3 m from the hole. Participants wore shutter goggles to inhibit visual feedback of outcomes. The aim, address, ball launch direction (analyzed as angles), and kinematics of the putter head and ball were measured. The results of this study experimentally confirmed the amateur side and indicated that the aim, address, and launch directions of the amateurs were smaller than those of the professionals. As for reproducing the slope task, we found that the amateurs underestimated the steepness on both conditions when compared to professionals. Additionally, golfers' aim and slope recognition were weakly correlated. These suggest that amateurs, compared to professionals, were unable to choose the optimal speed of the putter head and the launch direction of the ball in relation to the slope. Furthermore, amateurs' recognition was worse than that of professionals, which may affect their aim.

Fig 1. Experiment setting and an example of all ball trajectories for a professional golfer in both conditions.

(A) represents the pattern diagram of the experiment setting, while (B) shows the definition of measurements and an example of all ball trajectories for a professional golfer in both conditions. The experiment area where the putting platform was set was surrounded by curtains. The area surrounded by the red line indicates where participants could move freely to read the green. Two sensors were placed so that the shutter goggles would be activated when the ball passed the line 40 cm in front of where it was set. APD indicates the anteroposterior direction, while MLD indicates the mediolateral direction. The ball-hole line was approximately 19.3 degrees to the line parallel to the side of the platform and was to the right of the ball in the hitting direction. The clubface orientation of all phases was calculated as 0 degrees when the putter face was perpendicular to the ball-hole line. The green lines indicate the ball trajectory for the 1-degree condition, and the purple lines indicate the ball trajectory for the 3-degree condition. In addition, in the 3-degree conditions, it was not possible to identify the stopping position of the ball due to the size limitation of the putting platform. Therefore, the end of the plot of the ball’s trajectories represent the edge of the platform. Coordinates (0,0) indicate the initial ball position, and (3,0) indicate the center of the hole.

Fig 2. Miniature platform used in the slope reproduction task.

(A) shows the actual miniature platform (600 mm long x 910 mm wide x 300 mm high + 25 mm with feet). There are 12 boards (150 mm long x 225 mm wide x 4 mm high) on each side. (B) shows a part of it from the side view. The semi-circular feet (50 mm in diameter) were attached to the four corners of the platform. It was designed so that the slope could be adjusted by 0.5 degrees when one plate was inserted on both the left and right sides.

Fig 3. Average angles of each phase (A–C) in the 1- and 3-degree conditions.

Angle 0 refers to the center of the target. Negative values indicate the position to the left of the target’s center, while positive values indicate the position to the right of the target’s center. All error bars indicate ± 1SD.

Fig 4. Averages of peak speed of putter-head and ball speed near the hole in the 1- and 3-degree conditions.

(A) indicates the averages of peak speed of putter head. (B) indicates the averages of ball speed near the hole. All error bars indicate ± 1SD.

Fig 5. Relationship between ball launch angle and peak speed of all participants’ trials and hole-in trials.

The plots of all 240 trials involved ball launch angle and peak speed for the 12 professionals (A) and 12 amateurs (B). The blue and red plots show the averages and SD (± 1SD) of the hole-in trials in the 1- and 3-degree conditions, respectively.

Fig 6. Relationship between the number of boards inserted by participants and the aiming angle ranking in the 3-degree condition.

Aiming angles were ranked based on their values (1 = smallest, 24 = largest). The vertical axis shows the number of plates inserted by the participant after the trial.