Do Baseball Batters Keep Their Eye on the Ball?

One of the best-known pieces of advice in baseball is to keep your eye on the ball. In a recent survey, former college baseball players were asked whether they had been told to keep their eye on the ball when batting.1 Ninety-eight percent of the players answered yes. Despite the widespread use of this phrase, until about 10 years ago there were only two published eye-tracking studies investigating whether batters can and do keep their eyes on the ball after it is released by the pitcher.2 While both of these earlier studies continue to be highly influential, the question of whether batters point their eyes at a pitched ball throughout most of its flight remains unanswered.3

Recently, several groups have been examining eye- and head-tracking in baseball.4 Some of these more recent studies made use of wearable video eye trackers that allow for significant freedom of movement. The increase in work in this area has mirrored the remarkable rise in published sports vision studies over the past 15 years.5 In this paper, we explore aspects of batting, review the results of these papers, and look at future directions. This paper adds to and updates previous reviews on this topic.6

THE RELATIONSHIP BETWEEN TIME CONSTRAINTS IN BATTING AND EYE MOVEMENTS

To understand the challenges a batter faces in keeping his eyes on the ball, it is necessary to consider the time constraints involved in batting. A pitch that averages 90 miles per hour and that is released 55 feet from a batter will arrive at the plate in approximately 0.42 seconds, not much longer than a voluntary eye blink.7 The constraints are even more daunting because the time required to move the bat downward through the hitting zone is about 0.15 to 0.20 seconds.8

So in about a quarter of a second, a batter has to decide on the likely trajectory of the ball, whether to swing the bat, and where to move the bat to hit the ball. Once the downward bat swing begins, the batter may be able to “check” the swing. However, if the batter intends to complete the swing it is a matter of debate as to whether the originally planned swing is modifiable. We will return to this latter point momentarily. In that critical quarter of a second decision-making window after pitch release, the ball travels to within about 22 feet of the batter and the ball’s angular velocity is under 30 degrees per second. Some individuals can smoothly track an object traveling at velocities up to 100 degrees per second using eye movements called smooth pursuits, so maintaining the eyes on the ball during the first 0.25 seconds of the pitch should be relatively easy.9 As a pitched ball approaches a batter, the ball is effectively accelerating because the angle between the ball and the batter is increasing. However, this acceleration is not particularly dramatic until the ball is within about 10 feet of the batter. In the last 10 feet of ball flight, the ball reaches velocities over 400 degrees per second, easily exceeding the capacity of the eyes to smoothly track the ball.

Eye movements called saccades can rotate the eyes at much greater velocities than smooth pursuit. A saccadic eye movement “jumps” the eyes to a new location, as when reading words on a page or scanning a room for a familiar face. So when the pitched ball’s velocity surpasses the limits of smooth pursuit velocity, saccadic eye movements could be used to supplement smooth pursuit or to move the eyes at a similar or even higher velocity than that of the ball. However, vision is blurred during saccades (an effect termed saccadic suppression). This saccade-related blur could, for example, lead to a swinging strike if the batter incorrectly predicts the trajectory of the ball based on visual information prior to a saccade, and then the batter executes a saccade. Saccadic suppression during this saccade would limit the batter’s ability to evaluate the actual trajectory of the ball and correct the original trajectory prediction.

Moving both the head and the eyes together can allow batters to track targets at higher velocities than the eyes alone, but head movement introduces additional complexity in that the eyes tend to reflexively move opposite to the head. This reflex, termed the rotational vestibulo-ocular reflex or RVOR, can be canceled or suppressed to varying degrees depending on the velocity of the head, but reducing or eliminating the RVOR requires additional neural computations and may be so imperfect that the reflex pulls the eyes off the ball.10 The physiological limitations of the eye- and head-tracking systems suggest that a batter will likely struggle to keep his eyes continuously on the ball all the way from the pitcher’s hand to the point of contact with the bat.

MODEL-BASED vs. ONLINE MOTOR CONTROL

Of course, if a batter must decide whether to swing the bat and where to swing the bat very early in the pitch when eye and head movements are likely to be small, a reasonable question might be whether there is a point in studying these movements. The answer to this question depends on whether the swing can be altered later in the pitch in response to unfolding visual pitch-trajectory information. In an influential study, Higuchi and colleagues looked at the accuracy and variability of bat-ball contact when college baseball players hit balls pitched from a pitching machine at about 72 or 91 miles per hour.11 The location on the bat at which it made contact with the ball was assessed using high-speed video cameras. The batter was able to see the entire pitch in some cases, but in other cases the batter’s vision was occluded either 0.15 seconds after the pitch was released or 0.15 seconds prior to the pitch arriving at home plate.

There were only nominal differences in the location of bat-ball contact between the various conditions, suggesting that batters only need to see the first 0.15 seconds of the pitch to successfully bat the ball. Higuchi’s result seems to support the idea that batting is under model-based motor control, in which the trajectory of the pitch is mostly predicted by the batter very early in the pitch. This prediction is derived by combining information about the game situation (for example, the pitch count), information gained from the pitcher’s motion prior to pitch release, and information associated with early ball flight cues, including the launch angle of the ball.

These information sources are used to modify a preexisting motor plan stored in the batter’s brain. This motor plan is based on an “internal” model of object trajectory derived from experience with, for example, the motion of projectiles such as pitched baseballs. In a recent paper, Gray challenged the notion that batting is based entirely on model-based control.12 Gray put forward a number of arguments suggesting that batting movements are altered throughout much of the pitch. In motor control theory, continuously adjusting an ongoing movement based on currently available visual information is termed online control. If baseball batters use online control rather than model-based control, then they may want to track the ball reasonably well for as long as possible.

One particularly compelling result that suggests that batting is under online control is that of Katsumata.13 In Katsumata’s study, college baseball batters hit pitches from a pitching machine. The timing of a number of components of the swing (defined as the entire sequence of batter motions), such as the step, foot landing after the step, and the bat swing, were assessed. Katsumata found that the variability of the earlier components of the swing was larger than that of the later components. This suggests that batters are using online control, in that they are continuously adjusting their swing based on unfolding visual information. Therefore, moving the eyes (and head) with the ball for as long as possible to process current pitch trajectory information may be an important aspect of batting.

EYE MOVEMENTS AND GAZE LOCATION PRIOR TO AND AT THE TIME OF BALL RELEASE

While the focus of this article is on eye and head movements after the pitcher releases the ball, there are interesting studies of batters’ eye movements prior to pitch release. For example, one study found that when the pitcher releases the ball, college batters look at the pitcher’s elbow while non-expert batters look at the “shoulder-trunk” region.14 Another study concluded that college batters look at the pitcher’s arm and the location of pitch release near the time the pitcher throws the ball, while non-expert batters look at the pitcher’s head and face.15 While these studies suggest that there are differences in where experienced and inexperienced batters look as the pitcher winds up and releases the ball, it is still an open question as to whether there is one fixation strategy that batters should use to maximize performance.16

Discussions of batter fixation strategies sometimes include the ideas of “soft focus” and “hard focus.” Soft focus is a strategy in which the batter looks in the direction of the pitcher but fixates on nothing in particular. Then, around the time of ball release, the batter shifts attention, or “zooms in,” on the ball. In contrast, hard focus is a strategy in which the batter attempts to fixate on something in the same direction as but behind the location where the ball is expected to be released.

Once again, whether either of these strategies is superior to the other is not clear. It could even be the case that a completely different strategy from these techniques, such as shifting gaze from the pitcher’s body to the point of release or looking at a reliable visual reference close to but not exactly at the release point, such as the pitcher’s elbow (termed the “pivot point strategy” by Gray), might lead to the best batting performance. It is even possible that the best fixation strategy for one batter may not be the same as that for another. A final study that looked at eye movements before the pitcher releases the ball was conducted during batting practice. The investigators reported that professional baseball batters look back and forth between the pitcher and the plate prior to the pitcher’s windup and delivery.17 The frequency of these eye movements was correlated with batting performance, suggesting that these movements may serve to warm up the eyes or the brain in preparation for the pitch. These eye movements may help to focus attention on the potential path of the pitched ball.

EYE AND HEAD MOVEMENTS AFTER BALL RELEASE

Research conducted on eye- and head-tracking after the pitch is released has had a resurgence over the past 10 years. All of the studies on the subject to date are summarized in Table 1.

 

Table 1: Studies on Eye and Head Movements After Ball Release

Study	Method	Results
Hubbard and Seng (1954)	Head movements of college players and major-league players observed in real games, and major leaguers filmed in batting practice.	Batters’ head movements were infrequent when swinging the bat. Eye pursuits stopped at 8–15 feet from the plate.
Bahill and LaRitz (1984)	Graduate students, college players, and one major-league player observing a ball approaching on a fishing line at 60–100 mph. Vertical movement of the ball was minimized. Bat swing was not permitted.	The major leaguer tracked the ball with a combination of eye and head movements while other batters tracked with eye movements only, or mostly head movements. A single predictive saccade was detected for one batter. The major leaguer tracked the ball accurately until about 5.5 feet from the batter.
Fogt and Zimmerman (2014)	15 college players calling out the number and color of the number written on tennis balls. Balls were thrown by a pneumatic pitching machine at 76 mph. Only horizontal eye and head movements were measured. Bat swing was not permitted.	On average, the ball was accurately tracked primarily with batters’ head movements, and eye movements were small until late in the pitch. No predictive saccades were found.
Fogt and Persson (2017, 2020)	Two former college players either purposely taking pitches or swinging at pitches thrown by a pneumatic pitching machine at about 75 mph. Both horizontal and vertical eye and head movements were measured.	Batters tracked the ball primarily with head movements, and eye movements were small. The ball was tracked accurately with no predictive saccades until about 5 feet from the batter when swinging, and the head and eyes were moved to the plate ahead of the ball when taking pitches. Batting efficiency was very good for both batters.
Higuchi and colleagues (2018)	Six college players swinging at balls thrown by a pitching machine at about 72 and 91 mph. Horizontal eye and head movements were measured. Movements of the bat were recorded with high-speed video cameras.	Batters tracked the ball with head and eye movements. Head movements were larger than eye movements. Head movements continued for longer periods for some batters than for other batters, but batting efficiency was similar across batters. Predictive saccades were not found.
Nakamoto and Mann (2018)	Two professional players swinging at balls thrown at 75 and 87 mph in virtual reality.	The difference in the ball location and batter’s head location at bat-ball contact was the most important determinant of hitting efficiency. Predictive saccades were not mentioned.
Fogt, Kuntzsch, Zimmerman (2019)	Fourteen non-expert batters calling out the number and color of the number written on tennis balls. Balls were thrown by a pneumatic pitching machine at 77 mph. Bat swing was not permitted.	The batters’ eyes were kept close to the ball primarily with head movements. Predictive saccades were not reported.
Kishita and colleagues (2020a)	Six professional players (three from top teams, three from farm teams) swinging at pitches thrown by former professional players at speeds between 59 and 80 mph.	Batters kept their eyes close to the ball primarily with head movements combined with eye movements opposite to the head. Predictive saccades occurred on every pitch. The location of the bat at bat-ball contact was correlated with head location for all of the batters, and with head and eye location for two of the farm batters. Batting efficiency was not related to eye and head movements.
Kishita and colleagues (2020b)	Nine college batters swinging at pitches thrown by a pitching machine at speeds from 50 to 87 mph	Batters kept their eyes on the ball early in the pitch primarily with head movements in the direction of the ball. Eye movements early in the flight of the pitch were either very small (faster pitches) or directed opposite to the head (slower pitches). Predictive saccades along with quick head rotations in the direction of the ball occurred on every pitch. The timing of predictive saccades was not based on the pitch speed or the distance of the ball from the batter. Batting efficiency was not related to eye and head movements.

 

Hubbard and Seng (1954)

In 1954, Hubbard and Seng published their classic paper on eye and head movements in baseball batting.18 They observed head movements of college and major-league players in games, and made movies of major leaguers taking batting practice. Hubbard and Seng reported that head movements and eye movements in the direction of the ball were uncommon when batters swung at the ball, but eye movements were more common than head movements. The eye movements that did occur stopped about 8 to 15 feet in front of the plate. Hubbard and Seng suggested that eye movements were either too slow to follow the pitched ball at near distances, or alternatively that there was no reason to look at the ball at very close distances since at that point the swing could not be changed.

Bahill and LaRitz (1984)

In 1984, Bahill and LaRitz published the second classic paper on eye and head movements of baseball batters.19 The batters included university graduate students who were presumably non-expert baseball batters, college baseball players, and one major-league player. The methods available to measure eye and head movements were much more quantitative than they had been in the 1950s. The batters viewed a ball that was pulled toward them using a pulley system at 60 to 100 mph. Vertical movement of the ball was minimized, so the motion of the ball was not the same as that of a pitched ball in a game. Very little data were gathered (for six pitches eye and head movement data were gathered over the entire pitch and for 15 pitches data were gathered only for a portion of the pitch), but many of the findings from this study are consistent with those from more recent studies.

Bahill and LaRitz found some differences between the major leaguer and the other batters, in that the major leaguer tracked the ball with both eye and head movements while some of the other batters tracked the ball using mostly head movements. Still others used mostly eye movements. The big-leaguer had very fast smooth pursuit eye movements, reaching velocities as high as 120 degrees per second. Combining these exceptionally high-velocity eye movements with head movements allowed him to track the ball until it was about 5.5 feet away. The other participants were only able to track the ball until it was about 9 feet away. One of the batters in the study showed a unique eye movement strategy. Instead of tracking the ball as long as possible, this batter took his eyes off the ball part way through the pitch and rapidly looked at a location ahead of the ball. The rapid eye movement is termed a predictive or anticipatory saccade, because the eyes are placed at or near a location that is expected to be occupied by the ball at some future instant.

As mentioned, saccades can reach velocities far greater than those of smooth pursuit eye movements, but the downside to saccades is that vision is blurred during the brief period of eye movement. Predictive saccades have been reported in many different sports, such as cricket, tennis, and table tennis. The purpose of predictive saccades is not entirely known, but Bahill and LaRitz suggested that predictive saccades could allow batters to see the ball hit the bat, and this would help them to predict the location of pitches in subsequent at-bats.

Fogt and Zimmerman (2014); Fogt and Persson (2017, 2020); Fogt, Kuntzsch, and Zimmerman (2019)

After Bahill and LaRitz published their study, 30 years elapsed before the issue of eye and head movements in baseball batting after pitch release was examined again. In 2014, Fogt and Zimmerman published a study in which 15 college batters tracked tennis balls projected at them by a pneumatic pitching machine.20 This was the first of several studies from this group in which a wearable eye tracker mounted on a frame and synchronized with one or two head-tracking devices was used.

These head-tracking devices included an inertial sensor and magnetic tracking technology. The velocity of the balls was about 76 mph. Batters were not permitted to swing the bat. The tennis balls had either black or red numbers written on them in several locations. The batters’ task was to call out the number and the color of the number on each pitched ball. While there was some variability between the batters, they generally followed the ball with their head and moved their eyes relatively little until the ball was very close. Batters tended to keep their eyes on the ball using these head movements, and predictive saccades did not occur. In follow-up studies from the same laboratory, two former college players swung at pitches and deliberately “took” pitches from the same pitching machine used in the original study.21

The investigators assessed horizontal eye movements for both the “swing” and “take” conditions in one paper and they looked at vertical eye movements only in the “swing” condition in the other paper.22 In the “swing” condition, for both the horizontal and vertical directions, the eyes were relatively close to the ball until the ball was about 5 feet from the batters. Once again, head movements were primarily responsible for keeping the eyes near the ball and eye movements were relatively small. There was no clear evidence for predictive saccades. Although there were minor differences between the eye and head movements of the two batters, both batters were very successful in hitting the ball. In the “take” condition, large horizontal head and eye movements occurred that allowed the eyes to be pointed at a location near the ball when the ball arrived at the plate. The behavior in taking a pitch may indicate that looking at the location where the ball is expected to cross the plate can help in predicting the location of future pitches, just as Bahill and LaRitz previously suggested. Finally, in 2019, these same investigators published a paper in which 14 non-expert baseball batters were required to call out numbers and the color of these numbers on tennis balls thrown at 77 mph from the same pitching machine used in previous studies from this group.23 The batters did not swing at the pitches. Head and eye movements of the non-expert batters were similar to those of college players: Head movements were larger than eye movements. Head movements kept the eyes close to the ball throughout much of the pitch.

Higuchi, Nagami, Nakata, and Kanosue (2018)

In 2018, Higuchi and colleagues published another study on eye and head movements.24 Six college players hit baseballs thrown from a pitching machine equipped with a mechanical arm at speeds of about 72 and 91 mph. In agreement with the results of several of the studies described above, Higuchi concluded that batters moved the head more than the eyes in tracking the pitch. Some of the batters stopped moving the head when the bat swing began, while others continued to track the ball. One batter tracked the ball all the way to bat-ball contact. Although there were differences in the head-tracking strategies between batters, batting efficiency was similar.

Nakamoto and Mann (2018)

Nakamoto and Mann also published the results of a study in 2018.25 The study was published as an abstract in the book of abstracts from the 2018 meeting of the North American Society for the Psychology of Sport and Physical Activity. These investigators studied two professional baseball players as they batted balls in a virtual reality setting. The ball speed was either 87 mph (fastballs) or 75 mph (changeups and curveballs). Batting accuracy was correlated with both the difference in locations between the ball and gaze (the location of the eye as determined by both the eye and head) and the difference in location between the ball and the head. The difference in the ball and head location at bat-ball contact was the most important determinant of hitting efficiency.

Kishita, Ueda and Kashino (2020a and 2020b)

Finally, Kishita and colleagues published two studies in 2020. In one, six batters from the Nippon Professional Baseball league in Japan batted baseballs thrown by former professional pitchers at speeds ranging from 59 mph (curveball) to 80 mph (fastball).26 Three of the batters played for top teams and three played on farm teams.

Overall, batters moved their heads in the direction of the ball throughout much of the pitch, while the eyes at first moved opposite to the head, perhaps because of the rotational vestibulo-ocular reflex. During the early part of the pitch, the head and eye rotations combined to keep the eyes close to the ball. At some point (80–220 milliseconds prior to bat-ball contact), a predictive saccade occurred, directing the eyes near the location of bat-ball contact. Predictive saccades occurred later in the pitch for batters in the top league. Predictive saccades also occurred later for fastballs when the batter knew that the pitch was going to be a fastball, compared to the situation where the batter was not informed whether the pitch was going to be a fastball or curveball. The location of the bat at bat-ball contact was correlated with head location for all of the batters and was correlated with head and eye location for two of the farm batters, but the influence of these correlations on batting efficiency is unclear.

In a second study, Kishita and colleagues studied nine college baseball batters.27 The players hit baseballs thrown from a pitching machine at speeds from about 50 to 87 mph. The results were similar to the first study, in that head movements in the direction of the ball were common, eye movements early on in the pitch were either very small (faster pitches) or directed opposite to the head and the ball (slower pitches), and predictive saccades along with “quick head rotations” in the direction of the ball occurred at a time after the ball was released. In tracking a moving object with the eyes, saccades can be triggered to get the eyes back on the object when the velocity of the object exceeds the capabilities of the ocular pursuits. However, the batters in the Kishita and colleagues study made predictive saccades before the ball reached velocities exceeding that of the pursuit system, suggesting that these saccades were associated with prediction rather than the speed of the pitched ball. These predictive saccades also occurred before the ball arrived at a distance from the plate at which the batter would be forced to make a saccade in order for the eyes to arrive ahead of the ball’s future location.

The idea that the timing of predictive saccades is based on something other than when the ball’s speed exceeds some value or when the ball arrives within some distance of the batter is further supported by the fact that the time at which the predictive saccades began was correlated with the time of bat-ball contact and the batter’s hip rotation, rather than the speed or distance of the ball from the batter. Finally, batting efficiency was not directly evaluated or related to eye and head movement patterns in this study.

SUMMARY OF EYE AND HEAD MOVEMENT STUDIES

In summary, with the exception of Hubbard and Seng’s study, these studies consistently show that head movements in the direction of the ball are common. These head movements, in combination with minimal eye movements, or eye movements opposite to the head, allow batters to keep their eyes on or near the ball at least until a predictive saccade is made. On the other hand, the occurrence of predictive saccades has not been consistent across these studies.

WHY MOVE THE HEAD IN THE DIRECTION OF THE BALL?

There have been attempts to address why batters move the head and eyes as observed in these studies. Moving the head in the direction of an approaching ball is seen not only in baseball batting but in other sports. For example, Mann and colleagues found that cricket batters make head movements in the direction of the ball.28 Shinkai and colleagues showed that table tennis players also make such head movements.29 The fact that these head movements have been found in multiple sports suggests that there is some advantage to this behavior. One potential explanation for this pattern of head movement was proposed by Mann and colleagues.30

These investigators suggested that head movement when striking approaching objects allows the ball to be maintained in the same direction relative to the head. Since batting a ball is based on computing the ball’s direction relative to the head and body (called the “egocentric” direction), turning the head with the ball and keeping the egocentric direction constant could save valuable time for the batter in determining where the ball will arrive at the plate.

ADVANTAGES OF THE CONTINUOUS TRACKING STRATEGY vs. THE PREDICTIVE SACCADE STRATEGY

Batters keep their eyes on the ball at least through the early portions of ball flight. The advantage of this strategy is that maintaining one’s eyes near the ball presumably helps in assessing early ball-flight information. This information includes the pitch’s launch angle, the rate of angular expansion of the approaching ball, and the ball’s vertical angular velocity, all of which are thought to help the batter to determine when and where the ball will arrive near the plate.31 After the early portion of the pitch, some studies found predictive saccades while others did not. The following section discusses the potential benefits of differing eye movement strategies.

PREDICTIVE SACCADES vs. CONTINUOUS TRACKING

As mentioned before, predictive saccades may be useful for predicting the trajectory of subsequent pitches.32 In addition, predictive saccades may shorten the time required by batters to program the bat swing.33 That is, since eye position can inform the brain about where the bat needs to go in order to hit the ball, placing the eyes at the predicted location of bat-ball contact may facilitate more rapid swing planning. Still another potential benefit of predictive saccades is derived from the finding that the onset of predictive saccades is correlated with the time of bat-ball contact and the batter’s hip rotation.34

This latter finding suggests that there may be an overall timing sequence involving eye movements, head movements, and body movements. It is possible that disruption of the timing of any of these movements could reduce batting efficiency. While predictive saccades may provide all of these benefits, published results suggest that predictive saccades are often made quite late in the pitch.35 In those cases, there is likely not enough time to change the bat swing based on eye position information after the saccade. In cases where predictive saccades occur relatively early in the pitch, pitch trajectories tend to be less predictable. This suggests (although it doesn’t prove) that predictive saccades are intended primarily to help batters predict pitch trajectories in future at-bats.

It should also be pointed out that predictive saccades may have additional or different benefits (compared to baseball) in sports such as cricket and tennis, where the ball bounces prior to being struck. In those sports, predictive saccades to the predicted location of ball bounce may allow the eyes to track the ball after the bounce even when the ball bounces in an unexpected direction.36 On the other hand, since batting is likely under online control, if batters want to swing at the ball, then they would want to continuously track the approaching ball in order to adjust the swing as the pitched ball approaches. Support for the continuous tracking strategy when hitting (compared to the predictive saccade strategy) comes from the results of studies demonstrating that estimates of when an approaching object will arrive are better when gaze is maintained on the approaching object compared to when gaze is maintained at the location where the object is expected to arrive.37 Similarly, estimates of where an approaching object will arrive are also better when the observers follow the object with the eyes.38

At this point, in agreement with Bahill and LaRitz, it appears that in baseball, the primary function of predictive saccades is to inform batters about future pitch trajectories. At least from a theoretical point of view, maintaining gaze on the ball is the best strategy when batting the ball, and predictive saccades are perhaps best used in learning new pitch trajectories.

EYE AND HEAD MOVEMENTS AND BATTING PERFORMANCE

While there are proposed advantages of particular eye-tracking and head-tracking strategies in baseball batting, there is only modest evidence thus far to suggest that any particular pattern of eye and head movements leads to better hitting. For example, by showing that eye- and head-tracking patterns were different between a major-league batter and lower-level batters, Bahill and LaRitz provided some indirect evidence that batting could be influenced by these patterns.39 Similarly, Kishita and colleagues showed that batters at higher levels make later predictive saccades than batters at lower levels, and that head location correlates with bat location for players at higher levels but head and eye location correlate with bat location for some players at lower levels.40 To date, Nakamoto and Mann have provided the most direct evidence of a relationship between head- and eye-tracking and batting.41 In their small study, these investigators demonstrated that batting efficiency correlates with alignment of the head and the ball at bat-ball contact. This latter result suggests that moving the head with the ball can directly impact hitting performance, at least in virtual reality.

CORRELATIONS BETWEEN BATTING METRICS AND EYE MOVEMENTS OUTSIDE THE BATTING CONTEXT

There is another aspect of this story that must be mentioned. There are studies that show that saccadic eye movements (measured outside of batting) are faster and more efficient in high-level baseball players.42 Pursuit eye movements (also measured outside of batting) have also been found to be better in these players.43 Better eye movements have also been correlated with better batting metrics.44 How can these studies be reconciled with studies in which batters’ pursuit or tracking eye movements are relatively small when hitting? There are several possibilities. It may be that while better eye movements and better batting metrics occur together, faster or more efficient eye movements may not be directly responsible for improved batting. Another possibility is that control of predictive saccadic eye movements may be associated with better batting, and this could partially explain some of the correlations between eye movements and batting.45 Finally, the neural circuitry in the brain that controls tracking eye movements overlaps substantially with the circuity that is responsible for combined eye- and head-tracking movements.46 This may explain why eye movements correlate with batting success even though batters’ head movements are usually larger than their eye movements, at least prior to a predictive saccade.

SUMMARY AND FUTURE DIRECTIONS

After the flurry of research activity in this area over the last 10 years, are we any closer to answering the question of whether and how baseball batters keep their eyes on a pitched ball? We believe that we are. In all but one of these studies, the eyes are aimed at the ball at least until a predictive saccade occurs. What is surprising is that when the eyes follow the ball, tracking is primarily accomplished by head movements rather than eye movements.

On the other hand, there are unanswered questions that will need to be addressed in future studies. For example, there are potential sources of variability that have not been fully considered, but that could affect the eye- and head-tracking results. Most of the tracking studies have included relatively few batters, and more studies are needed to determine whether individuals differ in their use of eye and head movements. In addition, for an individual batter, eye and head movements could vary depending on the distance of the ball in front of the plate when bat-ball contact is made, and depending on where the pitch arrives (for example, inside or outside).

Probably the most significant question that has not yet been answered in the area of eye- and head-tracking of pitched balls is whether a particular pattern of eye and head movements directly impacts batting. All of these aforementioned questions will best be answered by testing under game or game-like conditions where the predictability of the pitch is varied.

If it is found that particular patterns of eye and head movements directly impact batting, then it may be possible to train batters to emulate those behaviors that lead to batting success. Clinical trials assessing the efficacy of various forms of vision training for baseball batting have shown some positive effects on batting performance. In a 2021 review paper, Laby and Appelbaum listed seven such clinical trials, two of which included some form of eye movement training (termed oculomotor training).47 One of these latter trials included one Division I college baseball team.48 The other included 24 players from two Division I college teams.49 There is clearly a need for more clinical trials with larger numbers of participants to establish whether and which vision training methods lead to better in-game performance. Further, if it can be established that batting performance is better with a particular pattern of eye and head movements, these clinical trials could incorporate new training methods to teach batters to make use of these patterns.

While more clinical trials are needed to understand whether vision training methods lead to better baseball batting performance, it should be pointed out that these trials are difficult for many reasons. Accessing baseball players to participate in clinical trials, particularly players at the college and professional levels, is difficult.50 Players often have very limited time, and researchers may be in geographic locations that are not conducive to working with these players. Collaboration between everyone interested in improving baseball batting performance, including but not limited to researchers, sports vision practitioners, coaches, athletic trainers, and baseball teams, can help in facilitating the successful completion of future clinical trials, which may in turn lead to better batting performance in games. 

MASON CLUTTER is a student in the combined Doctor of Optometry and Master of Science program at the Ohio State University.

NICK FOGT grew up in western Ohio during the Cincinnati Reds’ “Big Red Machine” era. He is a professor at the Ohio State University College of Optometry, combining his baseball interests with his work in eye and head movements.

 

NOTES

1 Nick Fogt and Jacob Terry, “Survey of visual and predictive aspects of batting and eye care utilization in baseball players,” Journal of Sports and Performance Vision 5, Issue 1 (2023), e1–e15.

2 Alfred W. Hubbard and Charles N. Seng, “Visual movements of batters,” Research Quarterly. American Association for Health, Physical Education and Recreation 25, Issue 1 (1954): 42–57.

3 A. Terry Bahill and Tom LaRitz, “Why can’t batters keep their eyes on the ball?,” American Scientist Vol. 72, Issue 3 (1984): 249–53.

4 Andrew J. Toole and Nick Fogt, “Review: Head and eye movements and gaze tracking in baseball batting,” Optometry and Vision Science 98, Issue 7 (2021): 750–58.

5 Nick Fogt, Lawrence Gregory Appelbaum, Kristine Dalton, Graham Erickson, Rob Gray, “Guest editorial: Visual function and sports performance,” Optometry and Vision Science 98, Issue 7 (2021), 669–71.

6 Dan Aucoin, “How do batters see the ball? A review of gaze research in batting,” Driveline Baseball. February 25, 2019. Accessed February 8, 2024: https://www.drivelinebaseball.com/2019/02/batters-see-ball-review-gaze-research-batting/.

7 Kyung-Ah Kwon, Rebecca J. Shipley, Mohan Edirisinghe, Daniel G. Ezra, Geoff Rose, Serena M. Best, and Ruth E. Cameron, “High-speed camera characterization of voluntary eye blinking kinematics,” Journal of the Royal Society Interface 10, Issue 85 (2013), 20130227.

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