Tuesday, October 9, 2012

Visual Search Pattern Analysis Reveals Differences in How Experts and Novices See the Serve in Volleyball

In the sport of volleyball, service reception is best accomplished by athletes capable of identifying and interpreting relevant visual cues from the server and the ball and predicting where the ball will be served to and where it will arrive.  Indeed the essential key to passing, like playing defense, is the ability to anticipate the future both efficiently and correctly. 

Part of this process of anticipation involves athletes’ visual search patterns -- their eye movements -- while performing a volleyball skill.  Recent research has shed some light on this process, which helps explain one of the significant performance differences between experienced and inexperienced volleyball players.

In a study published in the International Journal of Applied Sports Sciences, researchers examined the visual search patterns of expert and novice volleyball players receiving serve and found that the two groups not only focused on different cues during the act of serving but also began tracking the ball at distinctly different times.[1]

Experts focused more on the server’s arm and shoulder area than novices did[2] and experts began tracking the flight of the serve significantly earlier than their novice counterparts.[3]  These findings suggest an important evidence-based approach to coaching reading in service reception.

It was also revealed that experts were capable of predicting the arrival point of the serve, resulting in their eyes coming off the ball immediately prior to contact, [4] while novices were unable to predict the target point and instead tried to maintain tracking all the way to contact with their platform (see Fig 1 – reproduced from original work).  This conclusion may dispel a volleyball coaching myth that passers should strive to track the ball directly into the platform.

Fig. 1

Figure 1. Frames from the mobile eye tracker video, showing the receiver’s view between expert (E) and novice (N) during the flight phase, and the direction foveal gaze as he watches it.
(1 = serve impact; 2 = 2frame after impact; 3 = 4frame after impact; 4 = ball flight peak point; 5 = 0.18sec before serve reception; 6 = 2frame before serve reception).


[1] Lee, S. (2010).  Does Your Eye Keep on the Ball?:  The Strategy of Eye Movement For Volleyball Defensive Players During Spike Serve Reception.  Int’l J. Applied Sports Sciences, 22(1) 128-137.

[2] Location variables were the server’s shoulder, arm, head, and impact point of the hand with the ball.  Experts fixated in the server’s shoulder and arm area for 66.20% of total locations.  Novices fixated on the same areas only 7.46% of total locations.

[3] Experts began tracking the ball within a mean of 0.14 seconds after the server's contact with the ball.  Novices had a mean tracking onset of 0.21 seconds – a rate nearly 33% slower than the expert.

[4] For experts, the time between the last eye fixation on the ball and actual reception was less than 0.18 seconds.