The purpose of this study was to investigate the effect of expertise levels (elementary school, middle school, high school, and university) and perceptual-action coupled and uncoupled (blur condition) on decision-making and visual search strategies in handball attack tactical situations. For this purpose, a total number of 28 people, 7 for each expertise level, participated in the experiment, and eight people, 2 for each expertise level, and two coaches participated in the interview, with 30 participants in total participating in this study.
All the participants were asked to wear eye movement tracking gear while they were presented with a handball attack tactical video clip and performed a task of quickly and accurately responding to the most efficient attack forms (shooting, passing, dribbling, 1:1 breakthrough) by watching a video that stops before a decisive attack occurs.
The videos are divided into four conditions (blur condition 0%, 4%, 8%, 12%) from 0% condition without blurring the screen to 12%, with the highest blurring coming in 40 short video clips in total. Participants were asked to speak verbally based on a Likert scale up to 1 - 10 of confidence for their choice, and the whole process was recorded during the experiment. In addition, two of the participants in each expertise level had an interview on the acquisition of perceived eye focus locations and information shortly after completing the experiment, and handball coaches were asked to have an interview asking variables for decision-making and visual search after all those experiments were completed.
Eye movement tracking system, video clip files, checklists for experimental image difficulty levels and validity, and perceptual response keyboards were used for this experiment. The data measured through the experiment were analyzed separately according to the ability of decision-making and visual search. Two-way ANOVA and two-way MANOVA were conducted to analyze the differences depending on expertise levels and blur conditions. In addition, variables related to the acquisition of information and the perceived eye focus locations through interviews were analyzed.
The results of the study are as follows. Firstly, the first variable for decision-making ability, indicating the difference in the expertise level and the blur condition at decision-making time, differs between elementary and high school and university levels at the 4% of blur condition. However, there is no difference in the condition of 8% and 12%. Besides, differences in decision accuracy resulted in lower decision accuracy with blur increasing at all expertise levels, but differences in expertise levels depending on blur conditions differed significantly at 4% condition.
Secondly, the results on visual search strategies reveal that the rate of visual fixation time and the expertise level and blur condition at the frequency of eye fixation have differences between blur conditions of 0% condition and 4% and 12% condition along with 4% and 8% condition. As for the visual search rate calculated by the ratio of the average eye fixation time and the frequency of eye fixation reveals that the higher the expertise level, the shorter the average eye fixation time.
Thirdly, the analysis of the visual fixation location identifies that as blurring increasing, the ratio of attacking areas for a player with a ball gets lower at the middle school level and higher expertise levels (high schools and universities) show a higher ratio of eye fixation position for players attacking and the captain defensive player. This is because they are perceived peripheral vision within the range with lower visual fixation location for the empty, meaningless space.
Lastly, interviews were conducted for in-depth analysis of perceived eye focus locations, and the acquisition and processing of information reveal no difference for the perceived eye focus locations but the difference in number for perceived eye focus locations.
Those results indicate that they had watched and wanted to watch the overall movements of players in defensive or attacking positions to select the most efficient attack in tactical situations at all expertise levels. However, the analysis of gaze behavior using eye movement tracking gear reveal that the most frequent eye fixation position was in the attacking player's area with a ball at a very high ratio compared to other areas.