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75
Chapter
4
Eye and Head Movements During the Golf
Putting Stroke
George K. Hung
Dept. of Biomedical Engineering, Rutgers University, 617 Bowser Rd., Piscataway, NJ 08854-
8014, PH: (732) 445-4137, FX: (732) 445-3753, EM: shoane@rci.rutgers.edu
4.1 INTRODUCTION
Sports medicine is becoming a very popular means of addressing specific
questions posed by athletes concerning the body’s forces and actions during
athletic motions. It has, for example, provided valuable information about the
golf swing and physical forces impacting on the golf ball (Hay, 1978;
Nicklaus and Bowden, 2002). Much of this information has been obtained
using high-speed photography (Barnes, 1919; Bobby Jones’ swing
photograph, 1939; golfswingphotos.com). Indeed, the components of the
golf swing have been studied in great detail over past 50 years. However,
there is a surprising lack of objective simultaneous measurements of eye and
head motion during the golf swing, especially in putting.
Putting is a crucial element in golf. This is demonstrated by statistics
compiled by the Professional Golfers Association, which showed that the
best players in the world expend approximately 40% of their total strokes in a
round on putting (partners.golfserv.com). Golf teaching professionals and
sports psychologists specific to golf have long taught the importance of
minimal or no eye and head movements throughout the putting stroke. The
eyes are important because they provide accurate perception of ball location
to result in successful execution of a putting stroke. If the eyes are fixated
elsewhere at a position other than the ball, this can lead to an improper stroke
76
George Hung
and a missed putt. Head position is also important because it allows for
maintenance of stability of the visual environment. If the head moves during
the stroke, this can lead to misalignment and a missed putt.
Different putter grip styles can be seen in the golf course. Through
empirical experimentation or having been taught by particular school of
thought, golfers have adopted different putting grips. Indeed, many golfers
try different grips over the years, and sometimes even in the course of a
round However, there has not been any quantitative measures of
physiological and physical parameters related to the putting stroke to
determine why a certain grip works for a particular individual or under a
particular circumstance (e.g., a short versus a long putt). . Previous
quantitative studies related to golf grips were concerned not with their effect
on putter performance, but rather on driving distance and accuracy. For
example, Alderman (196) tested 33 subjects and found no significant
difference between the overlapping (Vardon) and interlocking grip with
respect to distance, accuracy, and velocity and angle at impact. Also, Walker
(1964) compared driving performance using the overlapping, interlocking,
and baseball grips in 24 male golfers, and found no significant difference
with respect to distance and accuracy.
In modern golf, there are basically three types of putting grips:
conventional, cross-hand, and one-handed
(Pelz and Mastroni, 1991;
Degunther, 1996; Farnsworth, 1997). One-handed putting represents the grip
used for the long-shafted putter, where the left hand hold the putter near the
chin or chest and is anchored there. A detailed description of these grips is
given in Section
4
.2.2. Also, for this chapter, only the right-handed putting
style will be considered, although the results can be generalized for the left-
handed player.
To quantitatively assess the effect of grip style on eye and head
movements, a study was undertaken to record the eye, head, and putter
positions simultaneously during a putting stroke using the three putting-grip
styles (Hung, 2003). Seven novice players served as subjects. These players
were chosen in part because they possessed less pre-conceived bias in their
putting-grip style than more experienced players. Nevertheless, the findings
should be applicable to golfers regardless of their level of expertise. The
results show differences in eye and head movements for the different putting-
grip styles, which may provide important insights into the underlying
mechanisms behind the selection of particular putting-grip styles by
individual golfers.
Chap. 4. Eye and Head Movements During Putting
77
4.2 METHODS OF MEASUREMENT
4.2.1 Apparatus
The laboratory environment was designed to present reasonably closely a
real-life putting green environment while allowing for the recording of data.
It consists of a putting platform, putter position sensor, helmet mounted eye
movement sensors, and head movement measurement device (Patent
Pending; see Figs. 4.1a,b). The putting platform is covered by green
artificial turf that mimics the texture of the putting green. The platform is
constructed of standard
8
5
in. thick particle boards and are stacked up three-
boards thick to provide the full thickness of the platform. The platform is
comprised of three sections. The first section consists of embedded
phototransistors and is where the subject stands and executes the putts. The
other two sections can be adjusted so that putting distances of either 3 or 9 ft.
are possible.
The putting position sensor consists of 16 infrared photo-transistors
place in the middle-level particle board in the first section (Figs. 4.2a,b).
They are inserted into different pin positions in three electronic breadboards
which are sandwiched and secured in place by particle boards. The
resolution of the putting sensor is provided by the minimum spacing between
phototransistors, which is 1.2 cm. The breadboards, and in turn the photo-
transistors, are aligned in the direction of the putting stroke. A ribbon cable
connected to the photo-transistors transfers the electronic signals to a circuit
board outside of the platform. The circuit board processes the electronic
signals to provide a digital signal representing the instantaneous position of
the putter face. The signal is input to a PC.
The binocular horizontal eye movement monitor is a Skalar-Iris (Model
6500) helmet-mounted infrared reflection device (Fig. 4.3). It has a linear
range of ± 25 deg., a resolution of 5 min. of arc, and a bandwidth of 200 Hz.
The voltage output signals representing eye rotations in the two eyes are
input to a PC.
The head rotation movement sensor consists of a potentiometer that is
placed in an adjustable mount above the subject’s head (Figs. 4.4a,b). A
small rectangular magnet is glued to the end of the potentiometer and is
bounded by two plastic rectangular pieces to form the female coupling
member (Fig. 4.4a). Similarly, a small rectangular magnet is screwed into a
male coupling member (Fig. 4.4b). At the beginning of an experimental
session, while the subject takes his/her normal putting stance, the position of
cylindrical unit, which itself is screwed onto the top the helmet, to form the
head movement sensor unit is adjusted until the male and female
components are joined and the axis of the potentiometer is aligned
78
George Hung
(A)
(B)
Figure 4.1. Subject standing on putting
platform during an experimental trial. (a)
Subject wears a helmet (for eye and head
movement measurements) and prepares to
putt on the first section of the platform.
Note that under this section are the
embedded photo-detector arrays (see Fig.
4.2). (b) Two other sections are
combined with the first section to provide
the setup for the 9-ft putts. Turning
around the third section (where the hole
is) and removing the middle section
allows for 3-ft putts.
Figure 4.2. (a) Top view of first section
of platform where the subject stands (see
Fig. 4.1a) showing ball and photo-detector
locations. (b) Arrays of photo-detectors
embedded under the artificial turf in the
platform. Note the front array is offset so
that the ball movement will not trigger the
detectors. The relative position of the golf
hole is in front of the photo-detectors (i.e.,
in the direction below the figure).
Chap. 4. Eye and Head Movements During Putting
79
Figure 4.3. Subject wearing helmet
containing the binocular eye
movement sensor unit. The eye
movement sensor unit in each eye
contains arrays of infrared emitters
(upper black rectangular piece) and
detectors (lower black rectangular
piece). As the eye rotates, the
amount of infrared reflection from the
white part of the eye changes, which
can be recorded as a voltage change.
Figure 4.4a. The female component of
the head movement sensor consists of a
potentiometer cemented to a swivel
unit (upper left). A small square
aluminum platform is cemented to the
end of the potentiometer shaft. The
rectangular magnet is cemented on top
of the platform, and is flanked by 2
rectangular plastic members.
Figure 4.4b. The male component
of the head movement sensor
consists of a rectangular magnet
mounted on top of a threaded
cylindrical unit, which in turn is
screwed onto the top portion of
the eye movement helmet.
80
George Hung
approximately with an imaginary axis through the top of the head and
its center-of-rotation (Fig. 4.5). Rotation of the head about this axis will
result in rotation of the potentiometer, which in turn causes a change in
voltage in the head sensor output signal. The head movement sensor has a
resolution of 0.5 cm and is linear throughout the ± 25.0 cm display range (in
units of equivalent platform displacement in cm; see below for conversion
from head angular rotation in degrees to equivalent platform displacement in
cm). The voltage signal, which represents the head position, is then input to
the PC. The head movement sensor can be easily disengaged from the
helmet by simply having the subject take a step back away from the device.
A more recent innovation in our laboratory is the use of miniature eye
movement and head acceleration sensors, along with a remote putter motion
sensor, to wirelessly transmit the signals to a personal computer for display
and recording (Patent Pending).
4.2.2 Putting Grip Styles
Three putting-grip styles were used. In the conventional grip (Figs.
4.6a,b), the left hand holds the top of the grip portion of the putter shaft while
the right hand is placed below the left. In most players, the little finger of the
right hand is placed in a position just overlapping the gap between index and
middle fingers of the left hand. In the cross-hand grip (Figs. 4.7a,b), the
positions of the hands are reversed. The right hand holds the top of the grip
Figure 4.5. The head movement sensor is
assembled by attaching the female
component in the head sensor swivel unit
(see Fig. 4.4a) to the male component in
the helmet (see Fig. 4.4b). The swivel
unit is clamped onto a frame with three
directions of freedom of movement. The
swivel unit itself can be pivoted and rotated
about its stem. This allows for different
subject heights and head angles during the
putting stroke. During the experimental
setup, the shaft of the potentiometer that is
attached to the swivel unit (see Fig. 4.4a) is
aligned with the head in such a way that
only rotation about an imaginary axis
through the top of the head and its center-
of-rotation will turn the potentiometer,
which in turn provides the head rotation -
signal.
Chap. 4. Eye and Head Movements During Putting
81
portion of the putter shaft while the left hand is placed below the right. In
this position, the tip of the index finger of the right hand may be in contact
with the wrist of the left hand. In the one-handed grip (Figs. 4.8a,b), which
represents the action used for the long-shafted putter, the right hand holds
approximately the middle portion of the putter grip. For consistency in
interpreting the results, the same putter (37 in. Acushnet Bulls Eye FLU5S)
was used for all three putting-grip styles in all subjects.
Conventional Grip
(A) (B)
Figure 4.6. (a) Overall view of
conventional grip for putting in a novice
player (GH), where the right hand is
below the left hand. (b) Close-up view
of the conventional grip.
82
George Hung
Cross-Hand Grip
(A) (B)
Figure 4.7. (a) Overall view of cross-
hand grip for putting in a novice player
(GH), where the right hand is above the
left hand. (b) Close-up view of the
cross-hand grip.
Chap. 4. Eye and Head Movements During Putting
83
One-Handed Grip
(A) (B)
Figure 4.8. (a) Overall view of one-
handed grip for putting in a novice
player (GH), where the left hand is
placed behind the subject’s back. (b)
Close-up view of the one-handed grip.
84
George Hung
4.2.3 Experimental Procedure
Seven unpaid volunteer subjects were recruited from the Rutgers
University student community via word-of-mouth and advertisement. They
were all novice right-handed golfers ranging in age from 21 to 22 years,
with corrected vision of 20/20 or better. All were male except for one
female.
The experimental paradigm for each subject was as follows: the subject
first practiced 5 putts without the helmet to become familiar with the
conditions. Also, for each of the three putting-grip styles, as the subject took
a putting stance, the distance from the ball on the platform to the subject’s
eyes was measured. Just prior to the beginning of the experiment, the helmet
was placed on the subject’s head, and the positions of the infrared detectors
for the two eyes were properly adjusted. At the beginning of the trials, an eye
movement calibration trial was performed, where the subject fixated
sequentially on three known locations (left end, middle, and right end of the
photo-transistor array) on the platform. This provided accurate recording of
eye fixations during a putting stroke, measured in units of cm of
displacement on the platform. For the putting trials, the head movement
sensor was attached to the head. The potentiometer was pre-calibrated to
provide the conversion from a measured voltage change to the corresponding
angular rotation of the potentiometer shaft, which in turn corresponded to the
angular rotation of the head. This angle was converted to the displacement
of a hypothetical beam emanating from the center-of-rotation of the head
(approximated by the position of the center between the two eyes) on the
platform, in cm. In this way, all measurements (i.e., putter, eye, and head
movements) had the consistent unit of cm of platform displacement. The
subject was instructed to attempt to putt the ball into the hole using as natural
a stroke as possible. Each putt constituted a trial lasting 3 sec, and the result
of the putt (i.e., where the putt ended up relative to the hole) was tabulated in
a data sheet. Twenty trials were performed for each of two distances: 3 and
9 ft. This was repeated for each of the three putting-grip styles. The entire
experiment for each subject required about 90 min.
For each 3-sec trial, the putter, left eye, right eye, and head position time
courses were recorded on a PC at a sampling rate of 100 Hz. The resulting
data were analyzed using programs written in C++ and MATLAB codes.
The results were displayed in 4 channels as position time courses for putter,
left and right eye movements, and head movement. Also displayed were the
corresponding velocity traces. For each record, the beginning of the putt as
well as the end of the putt (i.e., point of impact, or at the point
corresponding to the return to the initial putter position) were marked
visually. The data were analyzed to provide: the duration of the putt and
Chap. 4. Eye and Head Movements During Putting
85
the standard deviations (STD; i.e., relative to the initial position) of
combined left and right eye movements as well as head movements during
the putt (i.e., from the beginning of the backstroke to the point of impact).
The data from each subject was averaged, and the averaged data for the
seven subjects were used in the statistical analysis. One-tailed t-tests
(MATLAB Statistical Analysis Toolbox) were performed to assess the
statistical significance of differences between the different putting-grip
styles for the various parameters: height to eyes, putt amplitude, duration of
putt, percentage of putts made, STD of combined left and right eye
movements during the putt, and STD of head movements during the putt.
4.3 EXPERIMENTAL RESULTS
4.3.1 Typical Movements
Typical 9-ft putt time courses for the three putter-grip styles are shown in
Figs. 4.9a-c to illustrate the general pattern of responses. The sign
convention is as follows: the forward stroke of the putt, leftward eye
movement, and leftward head rotation (i.e., nose points leftward towards the
hole) are assigned positive values. For the conventional-grip putt (Fig.
4.9a), note the slight rightward rotation of the head (i.e., negative value, or
away from the hole direction), probably due to shoulder rotation, during the
backstroke, and simultaneous automatic compensatory smooth eye
movements (called vestibulo-ocular response (VOR), or compensatory
rotation of the eyes in a direction opposite to head rotation to maintain
stable fixation in space) (Ciuffreda and Tannen, 1995) in the positive (or
towards the hole) direction. These two movements generally tend to cancel
each other to provide relative steady eye fixation on the ball. However,
incomplete compensation or disruptions due to other eye or body motions
will result in inappropriate eye fixation in space. Note also that at about the
moment of impact, there is a saccadic eye movement (or rapid rotation of
the eyes to acquire a new target, such as that seen during reading) (Bahill
and Stark, 1979; Hung, 2001; Hung and Ciuffreda, 2002; Pola, 2002; Stark,
1968) in the direction of the hole, which may possibly affect the release of
the putter following impact. The putting stroke shows relatively good
positive acceleration in the forward stroke, reaching approximately peak
velocity at impact (0 cm putter position).
86
George Hung
Conventional Grip Response Characteristics
Figure 4.9a. Time traces of putter, eye, and head movements for a typical 9-ft
putt using the conventional grip. The hole location is in the direction of the top of the
page. Positive and negative numbers represent movements towards or away from
the hole, respectively. Top trace - Putter position. 2nd and 3rd traces - Left and right
eye positions, respectively. The eye movements, via the calibration procedure, are
converted to units of cm displacement on the platform. Bottom trace - Head
rotation. The angle of rotation about
an imaginary axis through the top of the head and its
center-of-rotation
has been converted to equivalent movement of an imaginary beam
projected from the center-of-rotation of the head (approximated by the center
position between the two eyes) onto the platform, in cm. For all traces, the position
and velocity are designated by solid and dashed lines, respectively. Vertical dashed
lines were visually selected to encompass the duration of the putt from the beginning
of the backstroke to the point of impact. Sub. GH.
Chap. 4. Eye and Head Movements During Putting
87
Figures 4.9b,c. Time traces for a typical 9-ft putt using : (b) the cross-hand grip
(Sub. MG) and (c) one-handed grip (Sub. GH).
Cross and One-Handed Grip Response
Characteristics
b
c
88
George Hung
For the cross-hand grip putt (Fig. 4.9b), note the slight rightward head
rotation away from the hole, along with a slight compensatory VOR during
the putt. There is also a saccade in the direction of the hole, which occurs
prior to impact, but the overall eye position is approximately directly on the
ball at the moment of impact. The subsequent saccades and head rotations
are simply tracking movement in following the path of the ball towards the
hole. Moreover, the putting stroke is near peak velocity at the moment of
impact.
For the one-handed grip putt (Fig. 4.9c), note the near absence of head
movements during the stroke, and the eyes are fixated approximately on the
ball throughout the stroke. Also, the putting stroke is near peak velocity at
the moment of impact. Subsequent saccadic and head rotations are
associated with viewing the path of the ball towards the hole. Also note that
the putter is held for a relatively prolonged period during the backstroke.
4.3.2 Across All Subjects
The results show differences between putting-grip styles [conventional
(Conv); cross-hand (Cross); one-handed (One)] for various parameters:
height to eyes, putt amplitude, putt duration, percentage of putts made, STD
left and right eye movements during the putt, STD of head movements
during the 3 ft (Table 4.1a) and 9 ft (Table 4.1b).
The data in Table 4.1a,b can be interpreted using an example. For the
first two columns under “Height to Eyes” for the 3-ft putt, the mean for the
conventional and cross-hand grips are 142.6 and 139.3 cm, respectively. To
determine whether the difference between the means is significant (i.e., is
conv > cross), a one-tailed t-test was applied (first column). The result is
that p = .031, indicating the difference is significant (i.e., p < 0.05, the
criterion level). A similar interpretation is used for all the other columns.
“Height to Eyes” is highest for one-handed, intermediate for
conventional, and lowest for cross-handed. This is because for the one-
handed putt, the subjects tend to stand more erect. On the other hand, for
the cross-hand grip, the left hand is positioned lower on the putter grip, thus
lowering the left shoulder. This tends to bring the head down as well, thus
lowering the height of the head relative to the platform. The “Height to
Eyes” findings are obviously the same for 3- and 9-ft putts. They are shown
for both distances for consistency in appearance of Tables 4.1a,b.
Chap. 4. Eye and Head Movements During Putting
89
Height to Eyes Putt Amplitude
Putt Duration (sec)
Mean
Conv
142.6
Cross
139.3
One
145.1
Conv
16.80
Cross
16.64
One
17.04
Conv
0.79
Cross
0.75
One
0.87
Hypo-
thesis
Conv
>
Cross
Cross
<
One
One
>
Conv
Conv
>
Cross
Cross
<
One
One
>
Conv
Conv
>
Cross
Cross
<
One
One
>
Conv
t - test
P =.031
SG
P =.002
SG
P =.032
SG
P =.417
NS
P =.334
NS
P =.362
NS
P =.213
NS
P =.005
SG
P =.004
SG
Percent Made (%) STD LE + RE Mov’t STD Head Mov’t
Mean
Conv
71.20
Cross
78.14
One
71.09
Conv
4.41
Cross
4.15
One
3.30
Conv
2.75
Cross
2.09
One
1.65
Hypo-
thesis
Conv
<
Cross
Cross
>
One
One
<
Conv
Conv
>
Cross
Cross
>
One
One
<
Conv
Conv
>
Cross
Cross
>
One
One
<
Conv
t - test
P =.121
NS
P =.121
NS
P =.493
NS
P =.312
NS
P =.066
TN
P =.025
SG
P =.076
TN
P =.151
NS
P =.018
SG
Table 4.1a - (3 ft putt) Comparisons among conventional (Conv), cross-hand (Cross), and
one-handed (One) grips for the averaged data in seven subjects using the t -test (one tail,
significance level set at p = 0.05) for 3 ft putts. STD = standard deviation. SG = significant, P
< 0.05. TN = trend, 0.05 < P < 0.10. NS = not significant. All values in cm of platform
displacement except where indicated.
“Putt Amplitude” is not significantly different for the three putting-grips
style for the 3-ft putt. However, for the 9-ft putt, amplitude for the cross-
hand grip is statistically significantly smaller than either conventional or
one-handed grip. This may be due to a restriction of the right elbow motion
in the backstroke as a result of the increased bend of the right elbow to
compensate for the higher right hand position on the putter for the cross-
hand grip.
“Putt Duration” is longer for the one-handed than either conventional or
cross-hand grip, for both 3- and 9-ft putts. This is due to the increased
length of the swing arm (putter plus hand and arm) in the one-handed putt.
Hence, if one considers this as a pendulum motion, the increased length
corresponds to an increase in the period of motion, and in turn an increase in
the duration of the putt.
90
George Hung
Height to Eyes Putt Amplitude
Putt Duration (sec)
Mean
Conv
142.6
Cross
139.3
One
145.1
Conv
22.13
Cross
20.38
One
22.55
Conv
0.77
Cross
0.80
One
0.91
Hypo-
thesis
Conv
>
Cross
Cross
<
One
One
>
Conv
Conv
>
Cross
Cross
<
One
One
>
Conv
Conv
>
Cross
Cross
<
One
One
>
Conv
t - test
P =.031
SG
P =.002
SG
P =.032
SG
P =.052
TN
P =.016
SG
P =.369
NS
P =.300
NS
P =.001
SG
P =.001
SG
Percent Made (%) STD LE + RE Mov’t STD Head Mov’t
Mean
Conv
33.4
Cross
47.9
One
41.6
Conv
5.91
Cross
5.06
One
4.23
Conv
2.79
Cross
3.04
One
2.16
Hypoth
esis
Conv
<
Cross
Cross
>
One
One
>
Conv
Conv
>
Cross
Cross
>
One
One
<
Conv
Conv
<
Cross
Cross
>
One
One
<
Conv
t - test
P =.006
SG
P =.274
NS
P =.242
NS
P =.099
TN
P =.016
SG
P =.038
SG
P =.358
NS
P =.153
NS
P =.127
NS
Table 4.1b - (9 ft putt) Comparisons among conventional (Conv), cross-hand (Cross), and
one-handed (One) grips for 9 ft putts.
“Percent Made” appears to be higher for cross-hand than either
conventional or one-handed grip, for both 3- (Table 4.1a) and 9-ft putts
(Table 4.1b), but these comparisons are not statistically significant except for
one condition. For the 9-ft putt, the “Percent Made” is statistically-
significantly higher for the cross-hand than conventional grip (p = .006).
The “STD of Combined Right and Left Eye Movements” is lowest for
one-handed, intermediate for cross-hand, and highest for conventional, for
both 3- and 9-ft putts. This holds except for the comparison between cross-
hand and conventional for the 3-ft putts (p = .312).
The “STD of Head Movements” is lowest for one-handed, intermediate
for cross-hand, and highest for conventional, for the 3-ft putts. This holds
except for the comparison between one-handed and cross-hand putts (p =
.151). However, for the 9-ft putts, there are no statistically significant
differences among the putting-grip styles. These findings suggest that head
motion plays a more important role in shorter (3-ft) than longer (9-ft) putts,
Chap. 4. Eye and Head Movements During Putting
91
and moreover indicates that one-handed grip, and to a lesser extent the cross-
hand grip, result in less head motion during the putt.
A simpler-to-visualize illustration of the same information as in Table
4.1a,b is shown in Table 4.2.
4.4 INTERPRETATION OF RESULTS
This study has provided some important quantitative insights into the
effect of grip style on eye and head movements during the putting stroke.
For minimizing head movements, there appears to be a slight advantage of
the one-handed grip over the other two grip styles, especially for the shorter
putts. This may be because for the conventional and cross-hand grips, the
right and left shoulders are linked due the coupling of the two hands. Thus,
during the backstroke, the movement of the hands causes the left shoulder to
dip slightly and the right shoulder to rise slightly. The natural linkage of the
shoulders to the head causes it to rotate slightly clockwise, as seen from
above. The opposite occurs during the forward stroke. In contrast, for the
one-handed grip, the two hands are not linked, so that movements of the
right hand and arm during the putting stroke rotates the right shoulder, but
with relatively little dip or rising motion. Moreover, since there is less
constrained coupling of the right shoulder to the head, the head motion is
relatively small during the putting stroke. Generally, players are reluctant to
attempt the one-handed putt perhaps because of a feeling that they may lose
control of the stroke. However, some professional players have used the
one-handed putting grip, notably Mike Hulbert, who used it in the mid-
1990s, and Lanny Watkins, who used it for short putts. Nowadays, the one-
handed putting style is manifested in the use of the long-shafted putter,
which is quite popular among senior players. An additional reason for its
use among senior players is discussed below.
Variation in eye movements were found to be least for one-handed,
intermediate for cross-hand, and highest for conventional grip. This is due
in part to the VOR. Thus, the smaller eye movements for one-handed grip is
partly due to the smaller head movements. However, not all eye movement
effects are a reflection of the VOR, since the statistical comparisons for the
different grips are not identical for eye and head movements (see Table
4.1a,b). There may be additional factors, such as posture and initial angle
of the head relative to the ball on the platform, that can affect the scanning
eye movements during the putting stroke.
92
George Hung
Table 4.2. Simpler-to-visualize illustration of same information as in Table 4.1a,b. Note that
the circle size represents relative parameter magnitude.
Chap. 4. Eye and Head Movements During Putting
93
The percentage of putts made was higher for cross-hand than
conventional grips for 9-ft putts. It may be possible that the higher
percentage made for the cross-hand grip is due a slightly more “solid”
impact of the putter with the ball, especially for 9-ft putts, as reported by
some of the novice subjects. On the other hand, although the direction of
the putt appear to be better for the cross-hand grip, there may be a reduction
in control of distance of the putt. This is seen in some of the novice player’s
putts that “fly past the cup”. Thus, there is not a clear-cut advantage of the
cross-hand over the conventional grip.
The duration of putts made was longer for one-handed than the other two
grip styles. This is due to the greater effective length of the swing arm
(putter plus hand and arm) of the putt. If one considers the putting motion
as being analogous to that of a pendulum, in which the period is related to its
length, then the longer swing arm for the one-handed grip would be
associated with a longer duration. A longer duration or slower putt may
provide improved timing in the putting stroke, thereby providing greater
consistency. This may explain why many senior golfers have, through
empirical experimentation with various putters, adopted the long-shafted
putter (using effectively the one-handed grip). Perhaps the reduction in
timing and control as one ages can be compensated in part by the use of a
putting grip style that provide a slower, more controlled, tempo.
The subjects used in this study were all college students between the ages
of 21 and 22. Most of them played other sports but all were novice golfers.
This pool of novice young golfers has the advantage of not having any
preconceived bias in favor of a particular golf grip. Also, they all have
relatively good eye-hand coordination, so that this would not be a limiting
factor in the study. Moreover, the narrow range of ages ensures a relatively
uniform subject pool, without large age disparities. It would, however, be
helpful in a follow-up study to investigate this effect in pools of subjects of
various age groups. Further, it would be very informative to test this in
expert golfers.
4.5 CONCLUSIONS
The experimental findings showed smaller variations using the cross-
hand and one-handed grips than the conventional grip. This holds both for
eye movements during longer putts and head movements during shorter
putter. Also, the one-handed grip exhibited longer duration than the two
other grip styles. However, when considered in terms of practical
applications, each putting grip style has its advantages and disadvantages.
The conventional stroke feels more natural and provides a sense of control
over the putt. This must be weighed against the perhaps slightly more
“solid” impact of the cross-hand grip and the better timing provided by the
one-handed grip. The cross-hand grip tends to lock the left hand and arm
94
George Hung
in a relatively fixed position, and thus reduces any “conflict” between the
right and left hands’ neuro-motor commands from the left and right cortical
hemispheres, respectively, which may cause the “yips” (a golf terminology
indicating a psycho-physical condition characterized by jitters during the
putting stroke). This, however, must be weighed against the slightly reduced
control over the distance of the putt. The one-handed grip provides the least
amount of head and eye movements. This occurs both because of the
absence of linkage between the shoulders and the hands, and because only
the left cortical hemisphere is involved in the neuro-motor command for the
right hand, thus eliminating any potential conflict in the command signals.
These benefits, however, must be weighed against the feeling of loss of
control over the stroke. Yet, actual testing of the one-handed grip on a
putting green can reveal that it is surprisingly accurate, and moreover, the
sense of loss of control can be offset in part by the use of a long-shafted
putter.
What do these finding tell us about the appropriate putting grip? Perhaps
a combination of grips should be considered. For example, for the longer
putts, use a conventional or cross-hand grip, whereas for the shorter putts,
use a one-handed or cross-hand grip. Each individual must decide for
oneself, through experimentation on the putting green and the golf course,
which grip or combination of grips works best. This study has provided
some of the quantitative and scientific rationale for gaining insights into the
mechanisms underlying such a decision.
4.6 ACKNOWLEDGEMENTS
The author thanks Rutgers University students Gary Horton, Brian
Cicalese, Nicholas Frietag, and Shana Groeschler for their assistance in the
laboratory.
4.7 REFERENCES
Bahill, T., and Stark, L., 1979, The trajectories of saccadic eye movements, Sci. Am. 240:
108-117.
Barnes, J. M., 1919, Picture Analysis of Golf Strokes. A Complete Book of Instruction.
Lippincott, Philadelphia, PA.
Bobby Jones’ Swing Photograph, by Dr. Edgerton of M.I.T. , 1939, A Peacock? No, It’s
Bobby Jones in Action!, The Bodine Motorgram, Bodine Electric company.
http://www.bodine-electric.com/Asp/MotorgramViewer.asp?Article=12
Ciuffreda, K. J., and Tannen, B., 1995, Eye Movement Basics for the Clinician. Mosby, St.
Louis, MO., pp. 112-114, 220-221.
Degunther, R., 1996, The Art and Science of Putting. McGraw-Hill, New York, NY.
Chap. 4. Eye and Head Movements During Putting
95
Farnsworth, C. L., 1997, See It and Sink It: Mastering Putting Through Peak Visual
Performance. HarperCollins, New York, NY.
golfswingphotos.com - Website for high speed photography of the golf swing; Al Ruscelli
Photography.
Hay, J. G., 1978, The Biomechanics of Sports Techniques. Prentice-Hall, Englewood Cliffs,
NJ, pp. 261-278.
Hung, G. K., 2001, Models of Oculomotor Control. World Scientific Publishing Co.,
Singapore, pp. 3, 102-110.
Hung, G. K. , 2003, Effect of putting grip on eye and head movements during the golf putting
stroke. TheScientificWorld. 3: 122-137.
Hung, G. K., and Ciuffreda, K. J., 2002, Models of saccadic-vergence interactions, in:
Models of the Visual System, G. K. Hung and K. J. Ciuffreda, eds.,. New York: Kluwer
Academic/Plenum Publishers, pp. 431-462.
Nicklaus, J., with Bowden, K., 2002, My Golden Lessons, New York: Simon & Schuster.
partners.golfserv.com - Web address for Professional Golf Association putting statistics.
Pelz, D., and Mastroni, N., 1991, Putt Like the Pros: Dave Pelz’s Scientific Way to Improve
Your Stroke, Reading Greens, and Lowering Your Score. HarperCollins, New York, NY.
Patent pending: Non-Contact Embedded Photodetector-Array Platform for Detecting Putter
Position. Serial nos. 60/296,574 and 60/317,944.
Pola. J., 2002, Models of saccadic and smooth pursuit systems, in: Models of the Visual
System, G. K. Hung and K. J. Ciuffreda, eds., Kluwer Academic/Plenum Publishers, New
York, pp. 385-429.
Stark, L., 1968, Neurological Control Systems, Studies in Bioengineering. Plenum Press, pp.
250-270.
Walker, A., 1964, The Relationship of Distance and Accuracy to Three Golf Grips, M. S.
Thesis, Springfield College, Springfield, MA.
