Published on: 6th June, 2003
By Paul Schienberg, PhD
Introduction: Background And History
Except for a few isolated cases, such as the preference of the lobster, crab and rat to use the right claw or paw, and the preference of cats to use their left paw, most animals are said to be ambidextrous and do not display lateral preference.
Preference for the right hand occurs in 90-95% of the population. Left hand preference is close to 10%. Ambidexterity occurs in approximately 5%. Left handedness is more common in males and in mentally retarded individuals (so if you are a male and retarded…..which to many women is redundant…..you figure it out.
Ocular or eye dominance is an entirely different situation. The first written description of ocular dominance is credited to Giovanni Battista della Porta in 1593. It was not until the late 20th century that serious attention was focused on this matter.
It might be expected that the eye that sees best is the dominant eye. This is not, in fact, the case. The dominant eye is usually considered to be the preferred eye for sighting. Eye dominance, preference or superiority is different from handedness or motor dominance.
Handedness is concerned primarily with motor aspects of motor organs. The eye is a sensory organ and has no conscious pro-prioception. And vision is for each eye represented bilaterally and equally in the brain in the occipital lobes, for most binocular animals. We have no consciousness of having a right and left eye as one is conscious of having a left and right hand. One does not see the world from a right or left eye, but from a single so called “cyclopean eye” which combines information from both.
When an athlete is asked to perform sighting tests, the cyclopean eye often seems to be located behind or close to one eye or the other. Eye dominance seems to be genetically predetermined. It is said that lateral dominance of a field of vision corresponding to the dominant eye, and it is easier for directional scanning to occur toward the field on the dominant eye and field. If persons are divided into only right or left eye dominance, then about 65% of the population is right eyed dominant and 35% are left eye dominant.
An individual who is right handed and right “eyed” or left handed and left “eyed” is said to have an uncrossed pattern of eye-hand dominance. Right handed and left “eyed” or vice versa is called crossed eye-hand dominance. There is no correlation between handedness and eye dominance.
A Study Of Baseball Performance
The study was conducted by a person (JMP) whose greatest frustration in childhood was that he didn’t become a good enough baseball player to make the major leagues. He could pitch but he could not hit a lick. He tired switch hitting and found much better success. He is right handed and has right eye dominant, uncrossed eye-hand dominant. He consulted his father’s history who was more successful in baseball. He found that his father was crossed eye-hand dominant, right handed with a dominant left eye, and had been a very successful batter, while uncrossed JMP had been a relatively successful pitcher. His father also had difficulty, in contrast, in pitching. The study looked a college varsity baseball team.
All twenty five, male, varsity athletes from the University of Florida baseball team were examined. Visual acuity, stereoscopic vision, ocular motility and eye sight dominance and handedness were established. All athletes batted the same “hand” as they threw except for one “switch hitter” who was right handed but who batter left handed.
Athletic performance was measured by data obtained from the prior year’s statistics. The pitchers were evaluated by their earned run average (ERA) and the hitters were rated by their by their batting average (BA).
Let me review some of the results of this study. College varsity level baseball players are twice as likely as the general population to have crossed dominance. The incidence of central eye dominance is considerably higher than the general population. The best hitters were centrally eye dominant or crossed eye-hand dominant. The poorest hitters were uncrossed eye-hand dominant. The top four pitchers were either uncrossed or centrally ocular dominant. Three of the top six pitchers were centrally ocular dominant.
What conclusion were the researchers able to draw from the results? There is strong support for the idea that the pattern of eye-hand dominance is significant and related to athletic success in baseball. There seems to be high probability that central ocular dominance helps athletes succeed in this form of athletic endeavor. The central ocular dominance players (batters and pitchers), whether right or left handed, were consistently and distinctly in the forefront. The central ocular dominant subgroup had both the best BA and the best ERA. The crossed eye-hand dominance pattern seems to be of benefit only to the batters – may even be a handicap to the pitchers. An uncrossed eye-hand dominance pattern is an advantage to the pitcher and a disadvantage to the hitter, and a crossed eye-hand dominance pattern is an advantage to the hitter and a disadvantage to the pitcher.
The situation for baseball hitting is very different from pitching in that the sighting action is to the side of the athlete. The explanation might be that there is increased ability of the eyes to sweep in the direction of the field of the side of the dominant eye. Certainly that is what the batter does. The pitcher is to his left and as he watches the pitcher he must make rapid sweeps of his eye from the plate in front of him to the pitcher on the mound, waiting for the pitch and watching the ball as it proceeds toward him. Even as the ball approaches him it is still primarily in his left gaze field, not the right gaze field, which it enters only when it crosses the plate and caught by the catcher. The batter must initiate his swing based on his vision of the ball’s course when it is perhaps only halfway or so from the pitcher to the plate, so it is irrelevant that the ball finally crosses into his right visual field as it crosses the plate. It is for these reasons why the crossed eye-hand dominant player is at some advantage in the batting situation over the uncrossed dominant player. The best combination for a baseball player would be a left handed centrally ocular dominant, or if not centrally ocular dominant, a left handed crossed eye dominant person. Many successful players do not follow this formula however.
Among those athletes that possess the other necessary qualities (speed, fast reactions times, coordination, competitiveness, etc.) for success, it may be that ocular dominance and the pattern of eye-hand dominance is another variable that is measurable and predictable.
Eye hand dominance could serve as a factor in scouting athletes, or guiding a young player on whether to hit left or right handed or to switch hit. It may be possible to determine what sport to concentrate on, as knowledge grows concerning the relations between ocular dominance and patterns of eye-hand dominance in other sports. Tennis is a natural next sport for examination.