Tjan, F. (Roy) (2010) The 'Off-Center Effect' in the Association Football Penalty-Kick Different Gaze Strategies in Perceiving the Imperceptible. thesis, Human Movement Sciences.
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Abstract
Introduction: The present study builds on the idea that it is possible for a goalkeeper to improve his or her chances of success in the penalty kick by influencing the decision-making and shot direction of a penalty kicker when standing off-centre (Masters, Van der Kamp & Jackson, 2007), the so-called 'off-centre effect'. In order for Masters and colleagues findings to have any possible generalization from lab to real-life competition and any practical implications for both football athletes and their coaches, the present study took a first step in testing the off-center effect in a more representative design. Furthermore, to gain insight into how decision-making and shot direction are shaped by an off-centre goalkeeper, we measured gaze behavior when penalty kickers prepared and shot at a projection of a 'real life' goalkeeper in goal. We hypothesised that an optimal gaze strategy does not exist for this task and that both foveal (goal comers focused gaze) and parafoveal (keeper focused gaze) gaze strategies are used by different individuals. Further, we expected that the use of either a foveal or parafoveal strategy would not yield differences in performance. Methods: Ten experienced association football penalty kickers were recruited as participants. Penalty kicks were executed in an indoor lab at a football goal projected onto a padded wall. The projected goalkeeper stood either in the middle, or to the left or right from the goal line center on different positions. Participants were instructed to shoot towards the largest open space in the goal in a total of 160 penalties from the penalty spot divided over ten conditions. Each condition was defined by a different clip projected onto the padded wall. Judgment accuracy was recorded and after each penalty shot, participants were asked to rate their confidence in judging the correct side (the side with the largest open space). A lightweight mobile, head-mounted eye tracker (MobileEye™, 25Hz) was used to monitor the participants' point-of-gaze during the experimental task. Results and Discussion: Results showed a similar trend as the off-center effect found by Masters et al. (2007). The effect seemed, however, not as strong as shown in their study. Masters and colleagues recommended an optimum displacement within a range of 1.6% to 3.0% (~area/area x 1 00) where penalty-kickers were unaware of the goalkeeper's position, but still susceptible to kicking to the open side. The present study, however, showed that within this range participants expressed with high levels of confidence that the goalkeeper was standing off-center. This could be due to the fact that, when performing in a more representative design, participants were able to use additional information, such as, reference points from the image of the goal (e.g., the netting) when making the relative area judgments. These sources of information were not available in Masters et al. (2007) study where the goal was represented by a black rectangle on a white background. Eye tracking data from 5 participants was suitable for further analysis. Results showed that participants functionally utilized both foveal (goal comers focused) and parafoveal (goalkeeper focused) gaze strategies when making the relative area judgments. Two individual participants used mainly a foveal strategy and three participants used mainly a parafoveal strategy. The utilization of these different gaze strategies did not yield any differences in performance/judgment accuracy. The present paper advocates for a new methodological conception in perception and action research in which studies first explore data on an individual-level, before averaging possible trends on an individual-level towards group effects.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Pepping, Gert-Jan |
| Supervisor name: | Button, Chris and School of Physical Education and University of Otago, New Zealand |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:51 |
| Last Modified: | 25 Jun 2020 10:51 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/1204 |
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