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A Protocol for the Comparison of Type 1 and Strong Left Dominance

A Protocol for the Comparison of Type 1 and Strong Left Dominance

INTRODUCTION

Something happens-that’s one thing.Why it happens,and what it amounts to, are different things entirely.People easily misinterprete obvious facts like that lipstick on your collar after the office night party.

The phenomenon of “Dominant Eye”probably falls into this category.The concept has been known for several years,but its implications are still not clear.We all know that most people are born with a dominant tendency to use one hand more than the other or one eye more than the other.Even if vision is perfect in both the eyes,one eye is mostly used to focus-an indication of dominance over the other.Therefore,we may say that a dominant eye is the one which is sighted towards the target.

The human species is predominantly right sided, showing a consistent manual preference from the early infancy.The dominant eye for distant vision is usually, but not always the same for intermediate or near vision. The importance of dominant eye is that although both eyes are used to judge the distance,it is the alignment of usually dominant eye,hand, foresight of the gun and the target,that gives the direction.So eye dominance appears to be important whether it is learned or innate and may predispose to a particular sport.

A categorisation of dominance has been proposed in which those athletes who are right eye dominant, right handed and kick with their right leg and have no other tendency towards left dominance are classified as type I dominant and all other have been put under type II category.

TYPE 1 AND STRONG LEFT DOMINANCE

Eye dominance is the tendency to prefer visual input from one eye to other.Approx imately 2/3rd of the population is right dominant.However prevalence of left dominance is also existing simultaneously.The dominance may be weak, strong or highly profound which has a fairly good impact on the various components of visual performance.

Visual acuity - Strong right dominance certainly predisposes to high acuity because it encourages a static relation between eyes and hand.It allows the development of stable aiming eye and these characteristics of vision are important to survive in the evolutionary period of man's development.It might be aiming an arrow on the animal or avoiding objects while running or seeing dangerous objects and animals quickly in order to avoid them.It is also important for good manual dexterity. The concept does not mean that left dominance cannot survive.They will also survive,it may be because of the brains ability to adapt and make the best of given circumstances. Research in tennis players have proved that vision of the players is so easily disrupted even if the non dominant eye is slightly blurred.

Depth perception – Type I individuals have stereopsis developed to a very high level which ultimately improves the depth perception whereas in the left dominance the stereopsis is not found to be developed to such a high level and the visual system is aware of this limitations.That is why strong left dominance has been found to have poor anticipation. The visual system ,therefore uses the other clues to judge the depth,if sufficient good information is not available from binocular vision. These monocular clues include – parallax magnification and colour. Once stereopsis is relieved of its responsibility, the visual system becomes less obsessive and small refractive errors have reduced effect.

Peripheral vision –In left dominance stereopsis is relieved of its responsibility,the visual system becomes less obsessive,then they are able to be more relaxed and peripherally aware.A relaxed athlete who is peripherallyaware will be able to detect the movement of the ball or other players more quickly like in football than some one who is concentrating more on central vision.Type 1 players are more engaged in high speed sports where visual concentration is very important for survival,hence they are less peripherally aware.

Contrast – Contrast sensitivity measures the visual systems ability to process or filter spatial and temporal information about objects and their backgrounds under varying lighting conditions or contrast level. Higher the athelete’s contrast sensitivity function profile, the more likely the athelete can discriminate as its velocity increases. In an high speed sport a strong right dominant athelete, the brain invests more energy into trying to interpret objects more in direct line of vision. Type I athelete tends to be more engagaed in high velocity sports therefore find their contrast sensitivity function decreased.

Visual correction –The decision to correct monocularly or even the importance of small binocular correction,is strongly influenced by the dominance type of an individual.For example, in Type 1,even small refractive error in the left eye can have a significant effect on the ability to judge depth.This really affects the mode of correction in the sports which require accurate depth perception or anticipation.Whereas left dominant athlete rely less on the stereoscopic judgement of depth,the decision made,therefore, will be different.

Conclusion -It is now possible to say that eye dominance has strong predispositions to a particular sports. It can predict which dominant type will favour which sport and which sport actually demand from the visual system in terms of visual acuity, relaxed vision and peripheral awareness. The sensitivity of Type I athelete does not mean that they can’t be visually relaxed, but it is much more important that their vision is properly corrected and in focus. And in summary, the two primary sport vision skill i.e aiming and anticipation are highly affected by eye dominance.

SUMMARY

Right dominance favours full stance and straight head.Therefore it is an advantage to be Type 1 as a batsman,since in batting aiming is an important visual skill.

Left dominant athletes are less affected by monocular blur.They are able to be more relaxed and in turn peripherally aware.In sport where acuity demand is not the greatest,this is a big advantage for the players like in football.The peripheral system is very fast at detecting movements,the central foveal area is relatively slow.

Type 1 players are visually disabled by even a modest amount of blur in their non- dominant eye.As shown in Tennis small amount of blur in non dominant eye significantly affected their ability to connect the ball.When non dominant eye is blured the strength of right dominance swamps the visual system making the athelete effectively monocular.