Saturday, November 28, 2015

Examining the Impact of an Attacker's Handedness on Anticipatory Judgments in Volleyball

Introduction

An athlete's left-handedness has a distinctly negative impact on an opponents' perceptual judgments.  This perceptual challenge leads lefties to a distinct advantage in interactive sports.[1]  In particular, left-handers' movements are more difficult to anticipate than those of their right-handed counterparts and the condition appears across a variety of sports including, soccer, volleyball, and tennis.[2]

Why are Lefties Harder to Read?

In the search for why, the emerging consensus is that athletes are under-exposed to left-handers and thus possess a greater lack of perceptual familiarity with their sport-specific movements.  Since the skill of anticipation depends heavily on accurately assessing the kinematic cues of opponents, less exposure to those cues equates to less opportunities to learn and a resulting disadvantage in reading performance.[3]  In other words, skilled perceptual judgment is attuned to more frequently encountered actions.  Indeed, this principle has lead one research group to observe, "[i]n volleyball players, the repetitive confrontation primarily with right-handed opponents in practice and competition is likely to explain better performance against right-handers.[4]

So this takes us to left-handedness in volleyball.  If lefties do have an advantage, how far does it extend into the sport and can the advantage be neutralized?  These issues and others have important implications for coaching professionals teaching tactical decisions, designing practice environments, and recruiting athletes to their programs.

Original Research - Anticipation of Shot Direction

As previously reported in an earlier post (Reading Revisited: The Challenge of Reading Left-Handers in Volleyball) (available here), researchers in 2012 sought to determine whether left-handed opponents were more difficult to read when attacking a volleyball by asking groups of skilled and novice players to predict the shot directions of left- and right-handed attacks in a video-based anticipation test.  Participants in both groups were better at predicting the directional outcome of  right-handed compared to left-handed attacks, with skilled players outperforming novices overall.[5]

If the left-handers' shot direction proved more difficult to predict than that of the right-handed players, would the handedness effect also extend to reading the lefties' choice of attack type?  Recent findings provide evidence that it does.

Recent Research - Anticipation of Shot Selection

A study published in Human Movement Science examined whether opponents shown video of an attack sequence could predict the type of attack ("smash" or "lob") planned by left- and right-handers with equivalent accuracy.[6]

Methods and Procedure

A total of 48 skilled volleyball players and novices participated by watching videos of left- and right-handed attacks on a computer screen. The videos were filmed from the perspective of a defensive player in either zones 1 or 5 of a volleyball court.  Each sequence included a reception/pass and a set to an attacker.  Attackers performed either hard or soft shots - "smashes" or lobs."  Videos lasted three seconds each and were temporally occluded to stop at the moment the attacker contacted the ball.

Further, to test whether prediction accuracy varied according to time in the sequence,each attack was occluded at six different time points relative to the moment of hand-to-ball contact: (a) 600 ms prior to contact, (b) 480 ms prior to contact, (c) 360 ms prior to contact, (d) 240 ms prior to contact, (e) 120 ms prior to contact and (f) at contact with the ball.  After the end of each video participants indicated whether they thought the attacker would perform a "smash" or a "lob."  There was not time limit for making the decision. 

Findings

Consistent with previous findings, skilled players outperformed novices in correctly anticipating the type of attack but left-handed attacks were harder to predict than right-handed attacks.  "A main effect for attackers' hand provided support for the notion that right-handed actions are easier to anticipate than left-handed actions.  Thus, an opponent's handedness seem to not only affect visual anticipation of outcome direction, but also the prediction of the type of an action (here, smash vs. lob in volleyball attacks)."[7]  Lefties, it seems are far more difficult to predict whether hitting or shooting the ball and regardless of the direction of their attack.

The question still remains as to why.  If it's simply the case that volleyball players train and compete against righties more than lefties and so are better attuned to the right-hander's movements why did both the experienced and inexperienced players underperform in predicting left-handed attacks?  Certainly the novices were not relying on their years of experience in the game against right-handers.[8]  The authors themselves acknowledge that the finding "appears unexpected" given the lack of competitive experience for the novices and posit that the novices' recreational exposure to volleyball likely over-exposed them to right-handed actions and that imbalanced experience provoked the handedness effect in the study.  

Clearly, its a question awaiting further study and one that is essential to our understanding of how best to train our volleyball athletes to neutralize the "lefty advantage."

Training Implications

Armed with knowledge that left-handers are more difficult to read what can we coaches do to improve our athletes' performances? Regardless of the need for more study it seems enticing to think that exposing our athletes more often to lefties in practice will increase opportunities to learn from their presence.  It's a practice fairly common in professional tennis with at least some anecdotal evidence to support it,[9] but no reported data supporting either short- or long-term improvement resulting from the practice.  It is also worth noting that tennis professionals seem to seek out lefty training opponents more to practice standard tactical adjustments against them and less to refine visual perceptual acumen.

On the experimental side, there is some evidence to support the notion that increased visual exposure to left-handed movements can reduce the effect of the left-hander's advantage.  In research published in the Journal of Sports Sciences, for example, a video-based perceptual training program was shown to improve the performance of participants predicting the directional outcome of left-handed penalty shots in handball.[10]  It thus seems plausible that a coaching manipulation of the training environment to increase the prevalence of left-handed opponents in volleyball is a potentially fruitful avenue of performance enhancement.


NOTES

[1] We address here an only "advantage" resulting specifically from being less predictable and not from the tactical preferences of opponents.  See Loffing, F., Hagemann, N., & Strauss, B. (2010).  Automated processes in tennis: Do left-handed players benefit from the tactical preferences of their opponents?  Journal of Sports Sciences, 28, 435-443.  See also, Sampras, P., (1998). Don't let southpaws scare you: After losing some tough matches to left-handers, I've learned how to handle them.  Tennis, 34, 142-45 (discussing tactical advantages for left-handed tennis players resulting from tennis scoring system).

[2] McMorris, T., & Colenso, S. (1996). Anticipation of professional soccer goalkeepers when facing right- and left-footed penalty kicks. Perceptual and Motor Skills, 82, 931–934.  Loffing, F., Schorer, J., Hagemann, N., Baker, J., (2012).  On the advantage of being left-handed in volleyball: further evidence of the specificity of skilled visual perception.  Attention, Perception, & Psychophysics, 74, 446-453Hagemann N (2009) The advantage of being left-handed in interactive sports. Atten Percept Psycho 71: 1641–1648 (tennis stroke).

[3] Urgesi, C., Savonitto, M. M., Fabbro, F., & Aglioti, S. M. (2012). Long- and short-term plastic modeling of action prediction abilities in volleyball.  Psychological Research, 76, 542-560.

[4]  Loffing, F., Hagemann, N., Schorer, J., & Baker, J. (2015).  Skilled players' and novices' difficulty anticipating left- vs. right-handed opponents' action intentions varies across different points in time. Human Movement Science, 40, 410-21, 417.

[5]  Loffing, F., Schorer, J., Hagemann, N., Baker, J., (2012).  On the advantage of being left-handed in volleyball: further evidence of the specificity of skilled visual perception.  Attention, Perception, & Psychophysics, 74, 446-453.

[6]  Loffing, F., Hagemann, N., Schorer, J., & Baker, J. (2015).  Skilled players' and novices' difficulty anticipating left- vs. right-handed opponents' action intentions varies across different points in time. Human Movement Science, 40, 410-21, 417.

[7]  Loffing, F., Hagemann, N., Schorer, J., & Baker, J. (2015).  Skilled players' and novices' difficulty anticipating left- vs. right-handed opponents' action intentions varies across different points in time. Human Movement Science, 40, 410-21, 417.

[8]  The novice participant group was comprised of 18 males and 8 females with a collective mean age of 24.77 years and "no experience in competitive volleyball or beach volleyball."  The authors acknowledge that the handedness-dependent performance differences in novices "appears unexpected." 

[9]  Sampras, P., (1998). Don't let southpaws scare you: After losing some tough matches to left-handers, I've learned how to handle them.  Tennis, 34, 142-45 (discussing tactical advantages for left-handed tennis players resulting from tennis scoring system and noting common practice to train against left-handers in advance of matches).  See also Crouse, K. (2011).  Left-Handers Have Edge in Slice and Singularity.  N.Y. Times (June 26, 2011), available at http://www.nytimes.com/2011/06/27/sports/tennis/2011-wimbledon-left-handers-have-benefit-of-slice-and-singularity.html?_r=0 (noting practice of training against left-handers in advance of matches to be played against lefty opponents).

[10]  Loffing, F., Schorer, J., Hagemann, N., Baker, J., (2012).  Human handedness in interactive situations: Negative perceptual frequency effects can be reversed!  Attention, Perception, & Psychophysics, 74, 446-453.

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