Some Observations and Questions on Handedness

Humans have had a long and storied relationship with tools. From rocks and sticks to pocket knives and sonic screwdrivers, we have depended on tools to make our lives easier and more efficient. But a recent study shows that our use of tools might also have a lot to do with how we use our hands. A study from the University of Sussex shows that our (humans’) penchant for right-handedness has a lot to do with what part of our brain thinks about how to manipulate tools. Our left hemispheres do most of the heavy lifting when it comes to how we interact with tools. This is how humans and their close cousins came to be right-hand dominant species. This also could help explain how humans developed speech, as the constant working of our left hemispheres — the side responsible for speech — caused them to get stronger.  However, the study shows that this dominance only manifests when the subjects were dealing with inanimate objects. When dealing with animate objects — like other animals or themselves — no real dominance was shown.

There are a lot of studies about handedness in humans — how it affects their personalities, relationships, careers, etc. From what I found, there really aren’t many on just how many people are left-handed. Perhaps that has to do with the fact that they don’t pass out a lot of grant money for just counting stuff. However, there seems to be a general consensus that about 10% of humans are left-handed. By left-handed, of course, I mean left-hand dominant. Many people fall somewhere in the middle along the Edinburgh Handedness Inventory.  I’m right-hand dominant, and very much so. I do everything I can think of as a righty, though I’ve been told I sweep like a lefty when curling. I know many people, and you may too, who switch it up, though. They may write and eat left-handed, but throw and bowl and play pool right handed. They may use their right to pick up the phone, but their left to open a door. Again, a lot of it comes down to what we’re interacting with. This is the point when I talk about actual baseball.

This started — like a lot of baseball writing, trust me — with an incorrect hypothesis. It seemed to me that there were less switch hitters than there were even a few years ago. So I ran the numbers, and I was wrong. Pretty badly wrong. So I expanded it out a little. I looked at the percentage of plate appearances that went to batters that the Retrosheet database defined as switch hitters from 1961 to now, commonly known as the expansion era.


This is more interesting. It seems as if there were very few switch hitters in the early 60s, and their heyday fell between the mid-80s and mid-90s.  They’ve tapered off a bit since then, but are still in higher numbers than even the early 80s. So, if all these plate appearances are going to switch hitters, from whom are they taking them?


It looks like they are taking them from right-handed hitters. In fact, there has been a pretty steady decline in right-handed batters since 1961, an almost 12% drop in fact. But why? If 90% of the population is right handed, why do right-handed batters only get half of the plate appearances? Are there just fewer righties in the league? Well, maybe.

Available data does not include what hand a player defines as their dominant hand. We can only deal with game data. Because of this, we have to make some assumptions. One of those assumptions I’m going to make is that the hand a player uses to throw is their dominant hand. It seems like a fair assumption, accounting for all but the truly ambidextrous. With that in mind, there seems to have been a slight drop in overall righties in the league.


But that’s only about a 5% drop, so it must be something else. Perhaps this is an indication that more naturally-right-handed players are focusing on switch hitting or hitting lefty. This makes a little bit of sense. Right-handed pitching has seen a bump over the past 20 years or so.


So it seems reasonable that GMs and managers are looking for players that can hit from the other side. However, right-handed throwers — that is to say, players that catch with their left hands — are still preferred or required in many positions such as third base, shortstop, and catcher. So a righty that can hit lefty might have an advantage.


Since 1961, pure right-handers have been in decline while right-handers who can hit from the other side have risen — though the exact way this hashes out has fluctuated. Are righty-righty players discriminated against? Do righties who can hit from the other side have a better shot of reaching the big leagues? Are young right-handers being taught to hit switch or lefty to help their chances in getting drafted or getting a scholarship to college? These are all questions I don’t have answers to, hence the title of this article. But it does seem that baseball players are continuing to break their natural inclination to use their right hands to manipulate tools. But is batting “left-handed” even a pure form of left-hand dominance? I mean, both hands are on the bat. Is it easier to get a right-hander to bat from the other batter’s box than it is to, say, teach them to write or eat or throw left handed? Man, it’s days like today I wish I were a neuroscientist.

The truth probably lies somewhere in the middle of all these questions. Natural lefties may be looked on more favorably. Natural righties may be learning to hit left handed. This issue — like a player’s clubhouse contributions or a managers true effect on a team — deals with sociology, psychology, and biology in a way we can’t boil down with simple game data. Maybe humans are evolving into some super race that can use both hands at will, and baseball is at the forefront. Or maybe the fact that we don’t make anything by hand anymore has led to a reduced need to rely on our left hemispheres. Whatever the case, we can put this in the bin where a lot of baseball research goes. We know that something is happening. We’re just not sure why.

David G. Temple is the Managing Editor of TechGraphs and a contributor to FanGraphs, NotGraphs and The Hardball Times. He hosts the award-eligible podcast Stealing Home. Dayn Perry once called him a "Bible Made of Lasers." Follow him on Twitter @davidgtemple.

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jim S.
10 years ago

I read somewhere that since a person’s eyes are of different strength, learning to bat LH (after beginning as a RH batter) might lead to a considerable improvement. I wish I could remember why, but I can’t. But I think it had something to do with the right eye (as a lefty batter) picking up the ball first. I began switch-hitting when I was 15 and my average went up 100 points.

Stuck in a slump
10 years ago
Reply to  jim S.

This is true, when I first joined the military they had me shooting right handed because I identified as a righty. Eventually as my shooting got worse one of my instructors asked which eye was better, my left or right. When I answered my left he had me shooting from that side and while it took a little bit of adjustment, I still shot better right off the bat.

I also had friends and family wondering what I was doing when I first picked up a pool cue and started shooting left handed when I was 7 or 8. I didn’t even know why, it just felt more natural. Given my early childhood problems with my right eye though, I wonder if I wasn’t just naturally adjusting.

10 years ago
Reply to  jim S.

I remember reading that Ted Williams regretted that his left eye was his stronger eye, since he would have had much more success if his right eye was stronger (as the lead eye).

Now imaging adding 100 points to his average….

Sam Horwich-Scholefield
10 years ago
Reply to  jim S.

I think you may be right. While about 20% of hitters are naturally left handed, less than 15% of switch hitters throw left handed (min. 450 PA in 2013). Smoak, Beltran, Nava, Swisher, and Melky are the only major league regulars I can think of.

‘ve done some research on BB/K splits for switch hitters, and although the sample size is small for natural lefties, it appears that being a being a switch hitting righty is generally more advantageous for this stat than being a switch hitting lefty, at least when comparing to league average. If we take BB/K rate to be a proxy for knowledge of the strike zone, then you could make an argument that hitting from the left side gives a batter a ‘better look’ than hitting from the right side. Natural left handers may see less of an advantage to switch hitting than their right handed counterparts.

10 years ago

Beltran throws righty, but that furthers your point

Ian R.
10 years ago

Perhaps rather than Beltran, you were thinking of Lance Berkman? I realize he didn’t get 450 PA this year, but he’s a very notable lefty-throwing switch-hitter.

Sam Horwich-Scholefield
10 years ago
Reply to  Ian R.

yes you’re right I meant Berkman. Beltran is a switch hitter who throws right handed.

10 years ago

Smoak and Swisher (partially) are 1Bs, where having the glove on the right hand (who cares about 1B throwing?) is an advantage. FWIW, Smoak claims to be a natural RH batter despite apparently being a natural lefty in some other ways.

Jim Price
10 years ago
Reply to  joser

But a lefty 1B does have a throwing advantage–not a big deal but its much easier for the throw to 2nd base.

10 years ago
Reply to  jim S.

Eyes work differently than the rest of the body when it comes to brain hemisphere. Per Wikipedia:

“Visual input follows a more complex rule: the optic nerves from the two eyes come together at a point called the optic chiasm, and half of the fibers from each nerve split off to join the other. The result is that connections from the left half of the retina, in both eyes, go to the left side of the brain, whereas connections from the right half of the retina go to the right side of the brain. Because each half of the retina receives light coming from the opposite half of the visual field, the functional consequence is that visual input from the left side of the world goes to the right side of the brain, and vice versa. Thus, the right side of the brain receives somatosensory input from the left side of the body, and visual input from the left side of the visual field—an arrangement that presumably is helpful for visuomotor coordination.”

Batting left handed means that the left half of each eye is picking up the ball which goes to the left hemisphere of the brain which controls the right hand. If having one eye being stronger than the other affects batting potentially that much than maybe eye dominance plays as big a role as hand dominance in determining which side of the plate a batter will be more successful from.

FanGraphs Reader
10 years ago
Reply to  jim S.

Could you please provide a link to the article that shows that your “average went up 100 points”?

10 years ago


Another FanGraphs Reader
10 years ago

Who cares? Batting average is a meaningless stat. I’d like to know how much his wOBA improved. And did he take park effects into consideration? What about the strength of competition before and after?

Some Other Fangraphs Reader
10 years ago

Clearly we’re dealing with SSS effects….