This dissertation has been microfilmed exactly as received 69-22,2X2 SNYDER, David William, 1934- THE RELATIONSHIP BETWEEN THE AREA OF VISUAL OCCLUSION AND GROUNDSTROKE ACHIEVEMENT OF EXPERIENCED TENNIS PLAYERS. The Ohio State University, Ph.D., 1969 Education, physical University Microfilms, Inc., Ann Arbor, Michigan I THE RELATIONSHIP BETWEEN THE AREA OF VISUAL OCCLUSION AND GROUNDSTROKE ACHIEVEMENT OF EXPERIENCED TENNIS PLAYERS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By David William Snyder, B.S., M,Ed. ****** The Ohio State University 1969 Approved by School of Physical Education f. I ACKNOWLEDGMENT The writer wishes to express his appreciation to Dr. John Hendrix who first suggested to him the possibility fo a dissertation involving the role of vision in hitting a tennis ball. Dr. Robert Bartels, the writer's adviser, lent great assistance in the selection and organization of the study. Mr. Larry Tracewell of the Ohio State Systems Engineering Department designed the special electrical instru­ ments used in this study. Without Mr. Tracewell's assistance the study would not have been possible. The subjects and scoring assistants were quite generous in offering their services and the writer is grateful for their contributions. Finally, the writer wishes to express his gratitude to his wife and family for their continued understanding and support. ii VITA December 14, 1934 * . Born - Wichita, Kansas L956 ................ B.S. University of Texas 1956-1957 ............ Physical education teacher and coach, Win­ field, Kansas, Junior-Senior High School 1958 ................ Physical education teacher and coach, San Angelo, Texas, High School 1958-1960 ............ Instructor of Physical Education and Tennis Coach, University of Arizona, Tucson, Ari­ zona 1960 ................ M. Ed., University of Arizona 1960-1964 ............ Assistant Professor of Physical Education and Tennis Coach, University of Arizona, Tucson, Arizona 1964-1965 ............ Teaching Assistant, Physical Education De­ partment, The University of Iowa, Iowa City, Iowa 1965-1967 ............ Associate Professor of Physical Education and Tennis Coach, University of Arizona, Tucson, Arizona 1967-1969 .......... Teaching Assistant, Physical Education De­ partment, The Ohio State University, Columbus, Ohio PUBLICATIONS "Sports Skills With A Future." Journal^ of Health, Physical Education, and Recreation, XXX, pp. 34 and 39, December 1959. FIELDS OF STUDY Major Field: Physical Education Minor Field: Teacher Education iii TABLE OF CONTENTS Page ACKNOWLEDGMENT ............................................ Ii VITA ........................................................ iii LIST OF T A B L E S .................. vi LIST OF FIGURES ............................................. vii Chapter I, INTRODUCTION..................................... 1 Statement of the P r o b l e m ..................... 1 H y p o t h e s i s .......... * ...................... 2 Assumptions and Limitations ................. 2 Significance of the Study ..................... 3 II, RELATED LITERATURE............................. 6 Athletes versus Non-Athletes ................. 7 Skilled versus Less Skilled Performers .... 8 Other Related Research ....................... 10 III. METHODS AND PROCEDURES............................ 15 Subjects...................................... 15 Equipment and Apparatus....................... 17 Ball Throwing M a c hine ..................... 17 Sensing and Triggering Devices ............ 17 O c c l u d e r .................................. lB Control B o x ............................... 18 Visual Conditions .......... * ............ 19 Broer-Miller Tennis Achievement Test ........ 19 P r o c e d u r e .......................... 21 The T e s t ................................. 21 Administration............................. 22 S c o r i n g ................................... 23 Important Controls ......................... 23 Weight of the B a l l ......................... 23 Court Marki n g s ............................. 23 Photocells and Occluders ................... 2k Ball S p e e d ................................. 2k Height of the N e t ......................... 2h iv TABLE OF CONTENTS— Continued Chapter Page Height of the Restraining R o p e . 24 Subjects' Hitting Area .............. 24 Instructions to Subjects . 25 Tennis Equipment............................ 25 Court Location.................................. 25 Recording, Equipment Operation, and Testing A s s istants .................................. 25 IV. ANALYSIS OF THE D A T A .................................. 26 Statistical Analysis .......................... 26 Summary ....... .............................. 30 D i s c u s s i o n........................................ 31 V. SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS ............ 36 Summary................... 36 Conclusions....................................... 37 Recommendations .................................... 40 APPENDIX A. SENSING, TRIGGERING, AND OCCLUDING DEVICE ............ 41 B. BROER-MILLER TENNIS ACHIEVEMENT TEST .................. 47 C. INSTRUCTIONS....................................... 50 D. SCORE S H E E T .......................................... 52 E. RAW FOREHAND AND BACKHAND SCORES...................... 54 F. ANALYSIS OF VARIANCE.................................. 57 G. DUNCAN MULTIPLE RANGE ................................ 59 H. PHOTOGRAPHS OF EXPERIMENTAL EQUIPMENT ................. 62 BIBLIOGRAPHY .................................................. 71 v I LIST OP TABLES Table Page 1. HEIGHT, WEIGHT, AMD AGE OF ALL SUBJECTS AND YEARS OF PARTICIPATION IN TENNIS ......................... 16 2. CONDITIONS OF OCCLUSION OR NON-OCCLUSION WITH THE BALL THROWN AT MEDIUM OR FAST SPEEDS UNDER WHICH THE SUBJECTS ATTEMPTED THE GROUNDSTROKES ...... 19 3. THE MEANS AND STANDARD DEVIATIONS OF FOREHAND AND BACKHAND SCORES UNDER ALL EXPERIMENTAL CONDITIONS . 27 k. ANALYSIS OF VARIANCE OF TEST SCORES OF FOREHAND AND BACKHAND GROUNDSTROKES WITH MEDIUM AND FAST BALL TOSSES .............................................28 5. THE RESULTS OF THE DUNCAN MULTIPLE RANGE TEST OF SCORES ACHIEVED UNDER ALL VISUAL CONDITIONS AND BALL SPEEDS USING FOREHAND AND BACKHAND GROUND­ STROKES .......................................... 29 6. RESULTS OF THE T-TEST OF THE MEAN SCORE DIFFERENCES OF TEST RESULTS AT THE TWO BALL SPEEDS.......... 30 vi LIST OF FIGURES Figure Page I. Scoring Areas for Broer-Miller Tennis Achievement T e s t ................................................ 20 vii CHAPTER I INTRODUCTION The physical movements and achievements of those who excel in athletic contests are often examined to assist in understanding and ex­ plaining why they do excel. Because of the emphasis often given to "keeping your eyes on the hall until you hit it" by those who instruct in sports such as tennis and baseball, where a participant attempts to visually track and hit a moving ball, the writer believed that some im­ portant implications might be drawn from an examination of the perform­ ances of experienced tennis players under varied conditions of visual observation. Statement of the Problem The primary concern of this study was to determine to what dis­ tance in front of him the experienced tennis player needed to visually track the ball prior to making a successful groundstroke. A second aspect of this study was to determine if a faster ball speed affected an individual's hitting accomplishment. A final aspect of this study was to determine at what distance in front of a player were the most critical points of observation in visually tracking an approaching ball. In investigating the importance of observing the ball until it is struck, the writer measured the groundstroking achievements under conditions that prevented the subjects' tracking the ball when it was a certain distance away. This blockage of vision, ox occlusion, oc­ curred when the ball was either three, six, or nine feet in front of the hitter. Achievement scores under varying conditions of speed, oc­ clusion, and no occlusion were statistically compared. Hypothesis In order to study the stated problem, groundstroke achievement was measured using the Broer-Miller Tennis Achievement Test^ with modi­ fications. Possible visual observation of the ball by the subjects was controlled by using a triggering and occluding device built especially for this experiment. The equipment and procedures of the study led to the testing of these hypotheses: 1, A faster traveling ball would re­ sult in lower achievement scored under the tested conditions when com­ pared to scores earned hitting a slower paced ball. 2. Scores would improve when it was possible for the subjects to see the ball longer up until that point when their eyes could no longer track or observe it and/or the swing was committed. Assumptions and Limitations It was assumed that the subjects' eyes attempted to follow the ball as long as possible when not occluded. Since vision is important in maintaining proper balance, it is possible that occluding vision affected the subject's balance and hence his swing in a manner not normally experienced. The subjects did not ^"Marion R. Broer and Donna M. Miller, "Achievement Tests for Beginning and Intermediate Tennis," Res earch Quarterly, XXI (October, 1950), pp. 303-13. complain or demonstrate obvious loss of balance during the testing, however. The testing situation called for