A recent episode of CBC's Quirks and Quarks featured a segment on curveballs. Despite a right-off-the-bat gaffe (Bob McDonald equates "breaking ball" with "curve ball"), it's an interesting segment that is unlike anything I've read in the online research community. Wanna hear about it?
The research comes from Dr. Howard Shapiro, a vision scientist and psychologist at American University in Washington D.C.
The basic idea of the research is that batters falsely perceive curveballs as having a "hump". As opposed to a fastball, the straightest pitch, and other types of off-speed pitches, which, although not as straight as fastballs still appear to travel in a fairly straight line, a curveball looks like it takes a precipitous dive at the last second. We're all familiar with the idea, even just from watching TV.
(By the way, a stat I've never seen before: curveballs apparently spin at about 1500 RPM. Obviously now I want to know whose curveball spins the fastest. Get on that, Fangraphs!)
In reality, this isn't the case. A curveball's trajectory is not a straight line, but its parabolic path is much smoother and straighter than batters perceive. The reason they see this sudden change in direction is related to vision - namely, central vs. peripheral vision. A curveball has two important components of motion: it's dropping and spinning. We can perceive both of these motions when we're looking directly at the ball, but when we switch to peripheral vision our brains can't handle them. It tries to combines them, loses some info in processing, and we perceive the ball as traveling at some angle relative to what we see with central vision.
To see this concept in action, check out the demo over at Quirks and Quarks' website.
"So", you say, "just keep your eye on the ball!" It's a good point! Why bother using your peripheral vision if it's just going to screw everything up? Unfortunately, it's unavoidable. As the ball gets closer and closer to the plate, the batter starts to perceive it with both central and peripheral vision simply because of its proximity.
In addition to that, batters don't, in fact, keep their eye on the ball. About halfway through a 0.6s pitch the batter's eye shifts from where the ball is to where he thinks it will be as it crosses the plate, so he can get his swing ready. This means, of course, he's only using peripheral vision to see the ball, and it's at this precise moment, when the ball's perceived trajectory abruptly shifts, that the batter sees a "hump". Shapiro claims that this last 0.3s in which the batter is perceiving a skewed trajectory results in an approximately 1-foot discrepancy between the ball's actual and observed location as it crosses the strike zone. Obviously batters have figured this out, so there's a great deal of guesswork involved in hitting a curveball. But even those who are great at it would admit that the less guesswork, the better.
Okay, so can batters learn anything from this? First, if they're able to track the ball for a longer period of time before switching to peripheral vision, the magnitude of the perceived break would be diminished. Second, says Shapiro, "practice makes perfect". It may seem like generic and obvious advice; obviously batters practice hitting curveballs all the time. It's a pretty important skill. He didn't really elaborate on this point, but I think the idea is that batters may be practicing the wrong things. Instead of practicing predicting the end location of a curveball, perhaps batters should be practicing letting it travel farther before taking their eye off the ball because of the diminished perceived break, even if it means leaving the batter with less time to get his swing ready.
"Dr. Shapiro, thank you very much!" No, thank YOU, Bob McDonald!
https://www.battersbox.ca/article.php?story=20101128234201107