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The effect of ocular dominance on the performance of professional baseball players
The Effect of Ocular Dominance on the Performance of Professional Baseball Players Daniel M. L&y,
MD,’
David G. Kirschen, OD, PhD,’ Arthur L. Rose&awn,
MD,2 Michael F. Mellman,
MD-’
Objective: The purpose of the study was to determine whether a performance difference exists between baseball players with “same” (right-right) and “crossed” (right-left) hand-ocular dominance. Design: A cohort study design was used. Participants: Four hundred and ten major and minor league members of the Los Angeles Dodgers professional baseball team. Intervention: Measurement of ocular dominance. Main Outcome Measures: Batting average and earned run average (ERA). Results: Same/crossed dominance (with P values in parentheses) are as follows: Batting averages: major league-0.271/0.251 (0.20); minor league-0.27410.270 (0.57); ERA: major league-3.341356 (0.66); minor league-4.00/4.20 (0.54). Conclusions: Hand-ocular dominance patterns do not have an effect on batting average or ERA. Ophthalmology
1998; 105:864
-866
Ocular dominance was first described in 1593 by Giovanni Battista della Porta in his work “De refractione.” ’ Since that time, abundant research has investigated the relationship between ocular and hand dominance. The effect of hand-ocular dominance on athletic ability has been a topic of some interest. In the sport of baseball, several reports have been published describing the effect of “same” (i.e., both right eye and hand or both left eye and hand dominance) versus “crossed” (i.e., left eye and right hand or right eye and left hand) dominance.*-’ Some authors believe that “crossed” dominance is an advantage for batters, since this allows the dominant eye to be naturally positioned toward the pitcher and the oncoming ball.’ Previous reports have evaluated little league,3collegiate,2’4and minor league players,’ but none has evaluated major league professional baseball players. If ocularhand dominance indeed plays a role in a player’s performance, this effect would be most easily observed in the major league player population. The major league is composed of a highly select group of athletes whose skills have been refined and developed to the highest level, thus creating a relatively homogeneouspopulation for study.
Methods Four hundred and ten members of the Los Angeles Dodgers professional baseball team were evaluated during the 1992Originally Revision
received: April 1.5, 1997. accepted: November 13, 1997.
’ Private practice, Herzliya, Israel. ’ Jules Stein Eye Institute, University of Cahfornla-Los Angeles, California ? Private practice, Los Angeles, California. Presented Academy
in part as a poster of Ophthalmology,
Reprint requests to Daniel auket, New York 11733.
864
Angeles,
Los
at the Centennial Meetmg of the American Chicago, October, 1996. M. Laby,
MD,
19 Washington
Avenue,
Set-
1995 baseball seasons. Eighty-four players were assigned to the major league, 25 1 were minor league players, and 7.5 players
were not assigned(e.g., releasedfrom their contract, assigned to the disabled list, and so forth). Due to the relative static nature of professional baseball teams, many of the players were tested over several seasons. Table 1 describes the number of players repeatedly tested and the final number of players used in the data analysis. Review of this table reveals that approximately half of the major league players were tested over one or more seasons, whereas only
30% to 35%of the minor leagueplayerswere repeatedlytested. Each player completed a brief historical questionnaire, lowed by evaluation of several different visual functions
fol(in-
cluding distancevisual acuity in each eye, distanceand near contour stereoacuity, distance random dot stereoacuity, and binocular contrast sensitivity).” Hand dominance for hitters was determined by the side of home plate they most often hit from, and for pitchers by the hand they threw with. Ocular dominance was determined by a modified Bryngelson technique.’ Each subject was asked to grasp a 12-inch cylinder (I.25inch diameter) with both hands in the midline below the waist. They were then instructed to raise the cylinder while keeping both arms fully extended and look through it at a distant object (such as the examiner’s nose). The examiner then determined which eye was directed down the tube and assigned that as the dominant eye. The procedure was repeated twice for each player. Batting averages and earned run averages (ERAS) for each player were provided by the Los Angeles Dodgers baseball team. In cases where a single player was tested more than once during the study period, performance data were averaged and used only once for analysis. In an effort to evaluate the most homogeneous populations possible, batting averages for pitchers were not included in the batting average analysis. Pitchers, as opposed to position players, do not train to improve their batting skills and instead work solely on improving their pitching skills (similarly, if ERA values were available for position players, they would /z~t be included in the ERA analysis). Statistical analysis using the two sample Student’s t test was performed for major and minor league hitters and pitchers separately. A P value of 0.05 was determined to indicate a statistically significant difference
betweentwo groups.
Laby et al * Hand-Eye Table
1. Number
of Players
Used
in Data
Before
Ma]“’ M lll”l‘ Total
players
and Baseball Performance Table
Analysis
Hitters League
Dominance
3. The
Effect
Before
After
49 138
26 87
35 113
20 80
187
113
148
100
Same Crossed Same Crossed ERA
Dominance
on ERA
n
ERA
SD
P
Major
11 4; 33
1.08 1.OJ 1.41 1.35
0.66
Mmor
3.34 3.56 4.00 4.20
Pitchers After
of Hand-Ocular
= earned run average;
SD = standard
0.54
deviation.
Before = total no. of players tested; after = no. of data pieces remammg after repeat players performance data were averaged.
Results Results of analysis of batting average and hand-ocular dominance are displayed in Table 2. In addition to the batting averages, standard deviations and results of two sample t test are shown. Although the batting averages in both leagues were higher for players with “same” dominance, this difference was not found to be statistically significant. Results of analysis of ERA and hand-ocular dominance are displayed in Table 3. Here as well, players with “same” dominance had superior ERAS, but the difference was not statistically significant. In addition to evaluating mean batting average and ERA, we ranked players by increasing performance scores. When evaluating batting averages, we found that five of the top ten major league hitters and two of the bottom ten major league hitters had “same” dominance, whereas six of the top ten minor league hitters and six of the bottom ten hitters had “same” dominance. A similar evaluation of ERA scores revealed that four of the bottom ten and seven of the top ten major league pitchers had “same” dominance, whereas live of the bottom ten and five of the top ten minor league pitchers had “same” dominance (Table 4).
Discussion Four previous reports have discussed the effect of handocular dominance on baseball players’ performance. None of the reports evaluated major league professional baseball players, although one has included AA minor league players.5 The first report studied a total of 28 players (hitters) from two collegiate teams.’ No statistically significant difference was found between the batting averages of players with crossed or same hand-ocular dominance,
Table
Same Crossed Same Crossed SD = standard
2. The
Effect of Hand-Ocular on Batting Average
Dominance
League
n
Batting Average
SD
P
Map
11 15 52 35
0.271 0.251 0.274 0.270
0.026 0.043 0.034 0.028
0.20
Minor
dewation.
although players with same dominance had a slightly higher batting average when compared with players with crossed dominance. The second report,3 involving 50 little league baseball players, evaluated the role of several visual skills in batting performance. After ordering the players by decreasing batting average, the authors found that all of the top 15 players had “same” dominance, whereas most of the ten worst hitters had “crossed” dominance. Although the range in batting average was large (0.100 to 0.439), no statistical analysis for the significance of this difference was performed. The third report4 evaluated 23 collegiate baseball players (in addition to 100 normal controls) and used a pointing test to determine ocular dominance. This test revealed both left and right dominance in addition to central ocular dominance. Although standard deviations and the results of tests of statistical significance are not provided, players with crossed hand-ocular dominance had a better batting average than those with same dominance. For pitchers, those with same hand-ocular dominance had a better ERA. Interestingly, players with central ocular dominance had the best batting averages and ERAS. The final and most recent report concerning the possible association between dominance and performance was published early in 1996.’ This report studied 2 15 members of the minor league (AA) Southern Baseball League. Ninety-two hitters were studied, and no statistically significant difference was found between dominance patterns and batting average. In addition, 88 pitchers were studied, and no statistically significant difference was found between their ERAS and their dominance pattern. Although not significant, pitchers with “same” dominance had a better ERA than those with “crossed” dominance patterns, whereas batters with “crossed” dominance had a slightly better batting average than those with “same” dominance patterns. Although the possible effect of hand-ocular dominance on baseball performance has been studied several
Table
4. Number of Players with “Same” Dominance Patterns
Hitters
Pitchers 0.57
Toll IO Major Minor
league league
7 5
Ocular
Bottom 4 5
IO
Tug 10 5 6
Botrom
IO
2 6
865
Ophthalmology
Volume 105, Number
times in the past, previous reports have disagreed over the effect of “same” or “crossed” dominance patterns on baseball performance. The majority of publications (including the present report) used a “forced choice” test of dominance, which allows only a right or left determination. One report,4 using a pointing technique, additionally allowed for central ocular dominance. Although we used an established dominance determination technique, it is possible that our findings would be different if we had included the possibility of central ocular dominance. In addition, previous reports have consisted of little league,
collegiate, or minor league players. No previous study has consisted of professional baseball players of both the minor and major leagues. Finally, one must also consider the fact that a multitude of other factors may affect a
player’s performance (e.g., daylight versus artificial lighting, weather conditions, and travel time) without regard to a player’s
hand-ocular
dominance pattern.
Our data, based solely on professional baseball players (both major and minor league), show no statistically significant difference between dominance patterns and ERA or batting average. In addition, no consistent pattern of dominance (same or crossed) was found in the best or worst groups of hitters or pitchers in either league. Our
866
5, May 1998
data do show a trend, in that players with “same”
domi-
nance had better batting averages and ERAS, but this difference was not statistically
significant.
It is possible,
although unlikely, that by adding additional data in the future, the power of the statistical tests can be increased, thus revealing a statistically significant result.
References 1. Fink WH. The dominant eye. Its clinical significance. Arch Ophthalmol 1938; 19557-X 2. Adams GL. Effect of eye dominance on baseball batting. Res Q 1965; 36(1):3-9. 3. Falkowitz C, Mendel H. The role of visual skills in batting averages. Optom Weekly 1977; 68(20):33-6. 4. Portal JM, Roman0 PE. Patterns of eye-hand dominance in baseball players. New Engl J Med 1988; 319:655-6. 5. Class6 JG, Daum JDK, Semes L, et al. Association between eye and hand dominance and hitting, fielding and pitching skill among players of the Southern Baseball League. J Am Optom Assoc 1996; 67:81-6. 6. Laby DM, Rosenbaum AL, Kirschen DG, et al. The visual function of professional baseball players. Am J Ophthalmol 1996; 122:476-85.
MD,’
David G. Kirschen, OD, PhD,’ Arthur L. Rose&awn,
MD,2 Michael F. Mellman,
MD-’
Objective: The purpose of the study was to determine whether a performance difference exists between baseball players with “same” (right-right) and “crossed” (right-left) hand-ocular dominance. Design: A cohort study design was used. Participants: Four hundred and ten major and minor league members of the Los Angeles Dodgers professional baseball team. Intervention: Measurement of ocular dominance. Main Outcome Measures: Batting average and earned run average (ERA). Results: Same/crossed dominance (with P values in parentheses) are as follows: Batting averages: major league-0.271/0.251 (0.20); minor league-0.27410.270 (0.57); ERA: major league-3.341356 (0.66); minor league-4.00/4.20 (0.54). Conclusions: Hand-ocular dominance patterns do not have an effect on batting average or ERA. Ophthalmology
1998; 105:864
-866
Ocular dominance was first described in 1593 by Giovanni Battista della Porta in his work “De refractione.” ’ Since that time, abundant research has investigated the relationship between ocular and hand dominance. The effect of hand-ocular dominance on athletic ability has been a topic of some interest. In the sport of baseball, several reports have been published describing the effect of “same” (i.e., both right eye and hand or both left eye and hand dominance) versus “crossed” (i.e., left eye and right hand or right eye and left hand) dominance.*-’ Some authors believe that “crossed” dominance is an advantage for batters, since this allows the dominant eye to be naturally positioned toward the pitcher and the oncoming ball.’ Previous reports have evaluated little league,3collegiate,2’4and minor league players,’ but none has evaluated major league professional baseball players. If ocularhand dominance indeed plays a role in a player’s performance, this effect would be most easily observed in the major league player population. The major league is composed of a highly select group of athletes whose skills have been refined and developed to the highest level, thus creating a relatively homogeneouspopulation for study.
Methods Four hundred and ten members of the Los Angeles Dodgers professional baseball team were evaluated during the 1992Originally Revision
received: April 1.5, 1997. accepted: November 13, 1997.
’ Private practice, Herzliya, Israel. ’ Jules Stein Eye Institute, University of Cahfornla-Los Angeles, California ? Private practice, Los Angeles, California. Presented Academy
in part as a poster of Ophthalmology,
Reprint requests to Daniel auket, New York 11733.
864
Angeles,
Los
at the Centennial Meetmg of the American Chicago, October, 1996. M. Laby,
MD,
19 Washington
Avenue,
Set-
1995 baseball seasons. Eighty-four players were assigned to the major league, 25 1 were minor league players, and 7.5 players
were not assigned(e.g., releasedfrom their contract, assigned to the disabled list, and so forth). Due to the relative static nature of professional baseball teams, many of the players were tested over several seasons. Table 1 describes the number of players repeatedly tested and the final number of players used in the data analysis. Review of this table reveals that approximately half of the major league players were tested over one or more seasons, whereas only
30% to 35%of the minor leagueplayerswere repeatedlytested. Each player completed a brief historical questionnaire, lowed by evaluation of several different visual functions
fol(in-
cluding distancevisual acuity in each eye, distanceand near contour stereoacuity, distance random dot stereoacuity, and binocular contrast sensitivity).” Hand dominance for hitters was determined by the side of home plate they most often hit from, and for pitchers by the hand they threw with. Ocular dominance was determined by a modified Bryngelson technique.’ Each subject was asked to grasp a 12-inch cylinder (I.25inch diameter) with both hands in the midline below the waist. They were then instructed to raise the cylinder while keeping both arms fully extended and look through it at a distant object (such as the examiner’s nose). The examiner then determined which eye was directed down the tube and assigned that as the dominant eye. The procedure was repeated twice for each player. Batting averages and earned run averages (ERAS) for each player were provided by the Los Angeles Dodgers baseball team. In cases where a single player was tested more than once during the study period, performance data were averaged and used only once for analysis. In an effort to evaluate the most homogeneous populations possible, batting averages for pitchers were not included in the batting average analysis. Pitchers, as opposed to position players, do not train to improve their batting skills and instead work solely on improving their pitching skills (similarly, if ERA values were available for position players, they would /z~t be included in the ERA analysis). Statistical analysis using the two sample Student’s t test was performed for major and minor league hitters and pitchers separately. A P value of 0.05 was determined to indicate a statistically significant difference
betweentwo groups.
Laby et al * Hand-Eye Table
1. Number
of Players
Used
in Data
Before
Ma]“’ M lll”l‘ Total
players
and Baseball Performance Table
Analysis
Hitters League
Dominance
3. The
Effect
Before
After
49 138
26 87
35 113
20 80
187
113
148
100
Same Crossed Same Crossed ERA
Dominance
on ERA
n
ERA
SD
P
Major
11 4; 33
1.08 1.OJ 1.41 1.35
0.66
Mmor
3.34 3.56 4.00 4.20
Pitchers After
of Hand-Ocular
= earned run average;
SD = standard
0.54
deviation.
Before = total no. of players tested; after = no. of data pieces remammg after repeat players performance data were averaged.
Results Results of analysis of batting average and hand-ocular dominance are displayed in Table 2. In addition to the batting averages, standard deviations and results of two sample t test are shown. Although the batting averages in both leagues were higher for players with “same” dominance, this difference was not found to be statistically significant. Results of analysis of ERA and hand-ocular dominance are displayed in Table 3. Here as well, players with “same” dominance had superior ERAS, but the difference was not statistically significant. In addition to evaluating mean batting average and ERA, we ranked players by increasing performance scores. When evaluating batting averages, we found that five of the top ten major league hitters and two of the bottom ten major league hitters had “same” dominance, whereas six of the top ten minor league hitters and six of the bottom ten hitters had “same” dominance. A similar evaluation of ERA scores revealed that four of the bottom ten and seven of the top ten major league pitchers had “same” dominance, whereas live of the bottom ten and five of the top ten minor league pitchers had “same” dominance (Table 4).
Discussion Four previous reports have discussed the effect of handocular dominance on baseball players’ performance. None of the reports evaluated major league professional baseball players, although one has included AA minor league players.5 The first report studied a total of 28 players (hitters) from two collegiate teams.’ No statistically significant difference was found between the batting averages of players with crossed or same hand-ocular dominance,
Table
Same Crossed Same Crossed SD = standard
2. The
Effect of Hand-Ocular on Batting Average
Dominance
League
n
Batting Average
SD
P
Map
11 15 52 35
0.271 0.251 0.274 0.270
0.026 0.043 0.034 0.028
0.20
Minor
dewation.
although players with same dominance had a slightly higher batting average when compared with players with crossed dominance. The second report,3 involving 50 little league baseball players, evaluated the role of several visual skills in batting performance. After ordering the players by decreasing batting average, the authors found that all of the top 15 players had “same” dominance, whereas most of the ten worst hitters had “crossed” dominance. Although the range in batting average was large (0.100 to 0.439), no statistical analysis for the significance of this difference was performed. The third report4 evaluated 23 collegiate baseball players (in addition to 100 normal controls) and used a pointing test to determine ocular dominance. This test revealed both left and right dominance in addition to central ocular dominance. Although standard deviations and the results of tests of statistical significance are not provided, players with crossed hand-ocular dominance had a better batting average than those with same dominance. For pitchers, those with same hand-ocular dominance had a better ERA. Interestingly, players with central ocular dominance had the best batting averages and ERAS. The final and most recent report concerning the possible association between dominance and performance was published early in 1996.’ This report studied 2 15 members of the minor league (AA) Southern Baseball League. Ninety-two hitters were studied, and no statistically significant difference was found between dominance patterns and batting average. In addition, 88 pitchers were studied, and no statistically significant difference was found between their ERAS and their dominance pattern. Although not significant, pitchers with “same” dominance had a better ERA than those with “crossed” dominance patterns, whereas batters with “crossed” dominance had a slightly better batting average than those with “same” dominance patterns. Although the possible effect of hand-ocular dominance on baseball performance has been studied several
Table
4. Number of Players with “Same” Dominance Patterns
Hitters
Pitchers 0.57
Toll IO Major Minor
league league
7 5
Ocular
Bottom 4 5
IO
Tug 10 5 6
Botrom
IO
2 6
865
Ophthalmology
Volume 105, Number
times in the past, previous reports have disagreed over the effect of “same” or “crossed” dominance patterns on baseball performance. The majority of publications (including the present report) used a “forced choice” test of dominance, which allows only a right or left determination. One report,4 using a pointing technique, additionally allowed for central ocular dominance. Although we used an established dominance determination technique, it is possible that our findings would be different if we had included the possibility of central ocular dominance. In addition, previous reports have consisted of little league,
collegiate, or minor league players. No previous study has consisted of professional baseball players of both the minor and major leagues. Finally, one must also consider the fact that a multitude of other factors may affect a
player’s performance (e.g., daylight versus artificial lighting, weather conditions, and travel time) without regard to a player’s
hand-ocular
dominance pattern.
Our data, based solely on professional baseball players (both major and minor league), show no statistically significant difference between dominance patterns and ERA or batting average. In addition, no consistent pattern of dominance (same or crossed) was found in the best or worst groups of hitters or pitchers in either league. Our
866
5, May 1998
data do show a trend, in that players with “same”
domi-
nance had better batting averages and ERAS, but this difference was not statistically
significant.
It is possible,
although unlikely, that by adding additional data in the future, the power of the statistical tests can be increased, thus revealing a statistically significant result.
References 1. Fink WH. The dominant eye. Its clinical significance. Arch Ophthalmol 1938; 19557-X 2. Adams GL. Effect of eye dominance on baseball batting. Res Q 1965; 36(1):3-9. 3. Falkowitz C, Mendel H. The role of visual skills in batting averages. Optom Weekly 1977; 68(20):33-6. 4. Portal JM, Roman0 PE. Patterns of eye-hand dominance in baseball players. New Engl J Med 1988; 319:655-6. 5. Class6 JG, Daum JDK, Semes L, et al. Association between eye and hand dominance and hitting, fielding and pitching skill among players of the Southern Baseball League. J Am Optom Assoc 1996; 67:81-6. 6. Laby DM, Rosenbaum AL, Kirschen DG, et al. The visual function of professional baseball players. Am J Ophthalmol 1996; 122:476-85.