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Tuesday, June 23, 2015

Watch: The optical illusion that makes it so hard to hit a curveball

Right when a curveball crosses the plate, the spinning of the seams tricks a hitter’s brain into thinking the ball is diving at a steeper angle than it really is. In the video above, you can see the same illusion at work — the circle is dropping straight down the screen, but its spin makes it seem like it’s moving to the left.

This is a well-known phenomenon called the curveball illusion. In a recent paper, a group of University of Rochester cognitive scientists conducted some tests to propose a new model of how the human brain uses motion to estimate the location of an object — and explain why it can sometimes be tricked.

They did so by carefully tracking the eye positions of study participants who watched videos of the curveball illusion and the related phenomenon of “peripheral slowing” (in which the circle about 1:10 into the video appears to spin more slowly when you’re not looking directly at it).

They argue that both these illusions — which only occur when an object enters your peripheral vision — are caused by assumptions your brain makes about position when it doesn’t have good data and can’t see the object clearly. In essence, it uses what’s called a Kalman filter: an algorithm that involves collecting a bunch of noisy data and making the best possible estimate based on all of it.

RoyalsRetro (AG#1F) Posted: June 23, 2015 at 02:43 PM | 19 comment(s) Login to Bookmark
  Tags: bats are afraid, curveball, science

Reader Comments and Retorts

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   1. Leroy Kincaid Posted: June 23, 2015 at 04:45 PM (#4984522)
I thought it did curve a little: Magnus Effect
   2. snapper (history's 42nd greatest monster) Posted: June 23, 2015 at 04:48 PM (#4984524)
I thought it did curve a little: Magnus Effect

It does curve. Just not as much as it appears to.
   3. the Hugh Jorgan returns Posted: June 23, 2015 at 05:15 PM (#4984544)
Well you can take all your illusionary trickery and pipe down. No matter how good the curve is, if you still throw a hanger it'll get crushed(see Bryant against Kershaw video for reference)
   4. Bhaakon Posted: June 23, 2015 at 05:20 PM (#4984548)
So the key to hitting a curve ball is mediocre eyesight. If you can't see the stitches moving, then you can't be fooled by the optical illusion.
   5. canoe Posted: June 23, 2015 at 05:46 PM (#4984559)
The optical illusion they highlight is an interesting enhancement, but it isn't what makes a curveball "drop off the table." If you look at the side view of the super slow-mo attachment, and envision the line of sight of the hitter, you can see from that perspective that almost all of the "drop" happens in the last 20-30 feet. This is based only on the arc of the ball's path. Dr. Adair covered this fully in The Physics of Baseball.

"Hanging" curveballs are just higher trajectory pitches that don't result in that same perspective.
   6. cardsfanboy Posted: June 23, 2015 at 06:29 PM (#4984576)
"Hanging" curveballs are just higher trajectory pitches that don't result in that same perspective.


I'm not really seeing what you are saying that is different with what the video showed. The point of the video is that as you use more of your peripheral vision, the more pronounced the motion is going to appear. Your example of a hanging curve basically agrees with that point.
   7. It's regretful that PASTE was able to get out Posted: June 23, 2015 at 06:41 PM (#4984579)
The hell it don't curve.
   8. salvomania Posted: June 23, 2015 at 06:56 PM (#4984580)
The optical illusion they highlight is an interesting enhancement, but it isn't what makes a curveball "drop off the table."

I always thought that a batter can only track a ball up until the last 10-15 feet, after which it moves into his peripheral vision, and if viewing a spinning object in your peripheral vision exgaggerates the effect, then this might explain the "dropping off the table."
   9. dlf Posted: June 23, 2015 at 07:12 PM (#4984586)
It's been far, far too many years since I took a physics class, but shouldn't the ball break more at the end simply due to the acceleration of gravity?
   10. Jim Wisinski Posted: June 23, 2015 at 07:16 PM (#4984588)
So that's why Jesus has trouble with it.
   11. Just drawing conclusions on the wall Posted: June 23, 2015 at 07:19 PM (#4984590)
It should be a rule that in any discussion of the physics of the curveball Dizzy Dean should be quoted. “Stand behind a tree 60 feet away and I’ll whomp you with an optical illusion!”
   12. cercopithecus aethiops Posted: June 23, 2015 at 07:26 PM (#4984594)
So the key to hitting a curve ball is mediocre eyesight. If you can't see the stitches moving, then you can't be fooled by the optical illusion.


You don't need good enough eyesight to "see the stitches moving" in order to perceive that the ball is spinning. If your vision isn't good enough to tell that the ball is spinning, then you probably can't hit fastballs, much less breaking stuff.
   13. TR_Sullivan Posted: June 23, 2015 at 08:36 PM (#4984639)
A movie titled "Trouble With the Optical Illusion" just doesn't work
   14. Steve Parris, Je t'aime Posted: June 24, 2015 at 12:13 AM (#4984806)
A movie titled "Trouble With the Optical Illusion" just doesn't work

Neither did "Trouble with the Curve"
   15. Jack Sommers Posted: June 24, 2015 at 12:18 AM (#4984807)
#11, believe it or not thats the first time I ever heard that. too funny.
   16. bjhanke Posted: June 24, 2015 at 03:47 AM (#4984823)
RE: #8 - Just thinking this through (I'm to a physicist), it seems to me that, during the last 10-15 feet of the ball's movement, the hitter is probably already into his swing. Your neck not being completely independent of your shoulders, being in the middle of your swing might keep your eyes from being completely focused on the ball at that time.

Also, cardsfanboy - We root for the same team, so I'm going to take the liberty of complaining about your idiom. The only absolutely correct Latin grammar idiom involving "different" is "different from." "Different than" started showing up over a decade ago, and there's currently a fad for "different to." But "different with?" I've never seen that one before. I'm well aware that living languages move, and I don't gripe too much about "different than", but "different to" still grates on me, while "different with" is, well, I'd mark it if I were proofreading (which I have done for a living). - Brock Hanke
   17. Bote Man Posted: June 24, 2015 at 11:03 AM (#4984947)
One way to test this is to gather a number of really great hitters (say, at something like, oh I don't know, an All-Star Game??) and start by having the best curveball pitcher hurl a number of curve balls to them, recording the results.

Then repeat the exact same test using balls that are colored completely white including the stitches and record the results. There would be almost no evidence of the ball's rotation on the all-white balls so the hitter would have only the trajectory of the ball to determine motion. The coloring should not disturb the stitches or else it would hamper the break of the curveball in flight, but I'm confident it could be done.
   18. Hysterical & Useless Posted: June 24, 2015 at 01:38 PM (#4985100)
Brock, "different" is notoriously promiscuous in the prepositions with which it will mate. I've gotten acclimated to "different to;" that's the default setting for all the Brits I work with, so I assume it's a Briticism. But I have to agree with you on "different with." Never seen it before. So either we never see it again, or we make it a meme.
   19. SandyRiver Posted: June 26, 2015 at 08:33 AM (#4986540)
"Hanging" curveballs are just higher trajectory pitches that don't result in that same perspective.


I think it's the same ballistic principle as sighting in a hunting rifle to make it shoot "flatter". One sets the sights so the bullet hits 2-3" high at 100 yards, and it will strike dead on at some distance 200-250 yards (depends on velocity) and only 6" or so low at 300 yards, thus close enough to aim directly at a deer-sized quarry throughout the entire range rather than having to aim high. Set the rifle so that it's dead on at 100 and it will strike low by 15"+ at 300 yards (thus, a miss), and be descending at a sharper angle than when the recommended sight-in method - the "hanging curve" - is used. A curveball has about one-twentieth the velocity of that rifle so everything is compacted in distance, plus it has spin to accelerate downward motion at greater than just gravity.

re: grammar. "Differing with" I've seen often, and though not as clear as "differing from", it's at least less weird than "different with".

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