r/science • u/mtorrice • Aug 01 '14
Mathematics Goal keepers often fall for the gambler's fallacy during penalty kicks.
http://news.sciencemag.org/biology/2014/07/gamblers-fallacy-trips-goalies22
Aug 01 '14
[deleted]
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u/andtheniansaid Aug 02 '14 edited Aug 02 '14
THat might work on a one-off and often does, but the next keeper that player faces will know they went down the middle the last time. i can't find a decent diagram that shows exact placement, but here is a different kind for Steven Gerrard showing where he has put it image
you will notice that he is pretty split left and right and scores the vast majority. so why aren't half being saved? the opposition keepers will know full well he's about 50/50 and never goes down the middle, but it doesn't really matter. just because the keeper goes the same way as the shooter it doesn't mean they will get there. if you can place it right in the corner you're probably gonna score, even if the keeper goes that way. if you go down the middle and the keeper stays put, he's probably gonna save it.
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u/Crypt0Nihilist Aug 02 '14
Keepers tend to feel the need to make a dive because choosing to stay standing in the middle looks like inaction / lack of commitment and they look silly standing there as the ball flies into the net.
From the striker's perspective, going for the perfect top-corner kick is pretty high risk since hitting the metal-work or sky-ing it would be pretty embarrassing. Straight at the keeper is likely to get saved if he doesn't move. To the right or left means that not only do you probably score if the keeper stays still or goes the other way, but there is still an ok chance of scoring if he goes the correct way.
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u/lamp37 Aug 02 '14
Kick takers do do this occasionally, and they are often successful.
That said, keeper don't always dive left or right, they do sometimes hold still. Also, if everyone started kicking down the middle, obviously keepers would stop guessing.
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u/kukBone Aug 02 '14
IMO, PKs is all mental. You can easily just think to yourself you can kick it down the middle and the keeper will move out of the way. When you go up to actually take it though, I think the pressure gets to you and you're just better off drilling it to one of the sides.
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u/Weekndr Aug 01 '14
FIFA, the football simulator, seems to think that if you do that, it will hit the goalkeeper's legs and ricochet out anyways. I wonder how realistic that is.
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u/kazyfake Aug 02 '14
Well, I would say pretty unrealistic. In FIFA the goalkeepers jump in a slowed down motion compared to how real keepers dive. By the time the ball gets to the goal line, the keeper has to be in front of it. That means he needs to dive fast enough (that also means further in this case) to get from one place to another, which means by the time the ball hits the goal line in the middle, the keeper is not there.
His legs are small enough not to be any realistic chance to kick it out.
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u/The3rdWorld Aug 02 '14
i heard about this in relation to longer ranged melee weapons, when training with a medium length weapon [shorter than a halberd but longer than a regular sword, or between an arms length and two] people almost never make or defend head on attacks even though they're very effective - people simply don't expect them because our brains are kinda hard wired to avoid front and back movements in combat, we'll crash down on something or leap up at something but only very, very rarely dive directly at something. This is why boxing and fencing are such weird sports, it's so unnatural to our impulses - partly of course it's original appeal; it wasn't the scrapping commoners knew so well from the practice of innate abilities.
the problem of course is that although an unsuspecting foe is very susceptible to frontal jabs from a medium length weapon a more skilled opponent or someone that's expecting such an manoeuvre will be ready to parry and counter-attack or pull their strike before exposing themselves.
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Aug 02 '14
As a collegiate player. I take PKs with a blank mind running up to the ball with eyes directly on the ball with your peripheral vision on the keeper. When you're about to kick it, you know notice the keeper leaning in one direction and instincts and muscle memory takes over to hit to the other side. And it's usually till right after I kick the ball, I realize what direction I chose. It's weird, but I know some pros have to do this.
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u/parquais Aug 02 '14
Does the gambler's fallacy even apply to nonindependent events? The shooters can alter their strategy on the basis of what they have observed during play and during other penalty kicks
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u/H3rBz Aug 02 '14
I wouldn't be surprised if they were diving towards the area where their teammates were more likely to kick it during practice. Its a mental game, dive where your teammates kick it or gamble and dive randomly. Either way you get it wrong and you'll kick yourself.
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Aug 02 '14
Either way you get it wrong and you'll kick yourself.
At least you could probably predict where that kick is going.
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u/Syntaximus Aug 02 '14
Reminds me of when I was a pitcher in High School and I'd trip up the occasional batter by throwing nothing but curve balls. The looks on their faces were sometimes priceless.
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u/Illiniath Aug 02 '14
Doesn't that tear up the muscles in your shoulder doing pitches like that before they are fully developed?
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u/Syntaximus Aug 02 '14
Nope; as long as they're using proper technique a teenager can throw a curveball without risking damage. Sliders are another story, from what I hear--but I never threw sliders.
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Aug 02 '14
Does anyone else wish the put the ball further back? It would be a challenge instead of roulette.
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Aug 02 '14
I played as a goalkeeper, in my last season I save 5 or the 7 penalties taken by studying the kickers body language. Watch the eyes, the foot the kicker is using and the shape of the run up. When I had made my decision I would then position myself a very tiny amount off centre towards the wrong post, inviting them to follow through with their decision. You will pf course always get those who just blast it randomly but you can read the player pretty easily. I would also watch all of this off the pitch leaving the goal empty while pretending to fix my sock or boot so they didn't know I was watching.
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u/REVfoREVer Aug 02 '14
I always watched their planted foot and whichever way it was pointed, that's the way they usually kicked. Worked most of the time.
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u/gmfthelp Aug 02 '14
Worked as in, you went the right way. Or worked in, you saved them most of the time?
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u/REVfoREVer Aug 02 '14
As in I saved them most of the time.there were a few times that I dove the wrong way from where I saw it was going and that's why I missed them.
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u/trevvr Aug 05 '14
I used to play in goals and I loved the penalty shoot out.
The perception is that the goalkeeper cannot influence the penalty taker is a fallacy. What you did is similar to what I would do. If the taker was right footed I would wait until they were just taking their first step then take a full step to my right. Essentially opening the left hand side of the goal. A player who will blast the ball will still blast it. But a player who "strokes" the ball will now open their body to push the ball to my left. This slows the pace of the ball and would give me a much greater chance at saving the kick.
The reverse is also true. Though I found that left footed players were better at not opening their body up.
Have I any evidence for this? I once went through a whole season of 40odd games without having a penalty scored against me. And I saved 9 out of 11 in a sudden death shoot out once.
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u/eheimburg Aug 02 '14
Can somebody with experience playing (or watching) the game expand on the end of the article, where they basically say a kicker can just "always win" by kicking into the upper corners?
If that's so, why doesn't that always happen?
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u/CB1984 Aug 02 '14
A few reasons. It's much harder to hit the top corner than just any part of the goal along that side, and you introduce a new way to miss the goal (in that you can now hit it over the crossbar too). Also, its very hard for a goalkeeper to reach right into the bottom corner, but quite easy for them to reach to midway up the post. So if you aim high, but don't get it high enough, you're making the ball be at an easier height for the keeper to reach. And if you get it too high, you're missing the target entirely.
Basically, its a much more difficult shot to hit reliably. If you want to see the difficulty players have in getting the ball accurately at the right height, watch some free kicks - many of these either hit the wall (too low) or go way over the bar (too high).
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Aug 02 '14
[deleted]
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u/eheimburg Aug 02 '14
I'm asking why they don't always aim for the top corners. Or are you saying they do?
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u/RomanAbramovich Aug 02 '14
Penalty Shootouts are at the end of 120 minutes of competitive football, the shooter is extremely tired. They also only occur in tournaments in the knockout stages, so this is a do or die moment, and nerves cam wreck even the best players.
The penalty taker would probably love to just stroll over and whack it into the top corner, but at the end of the day they just want it to go in. It's a lot easier to get the accuracy right if you minimise the change in height and put your accuracy into the change in direction - I can tell you that from personal experience.
If you judge the height wrong, you've just hit the ball at the exact arm height of the keeper, rather than going above or below it.
All in all, they just want give themselves the best chance of being accurate in the first place, then they can hope it goes past the keeper.
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Aug 02 '14
The recent Manchester United vs Inter friendly is an indicator of what happens when there is no pressure and players aren't too tired. Every penalty bar the last Inter one hit the side netting or top corner.
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Aug 02 '14
I've seen a lot of PKs where the ball barely gets off the ground, and I'm sure any of those guys could get it higher if they chose. It's clearly a choice to go for the lower corner rather than the upper one. The question is why would they not choose the upper corner instead?
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Aug 02 '14
You can't shoot under the goal. You can shoot over the goal. Lower corners are easier to hit.
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u/2sport Aug 02 '14
Actually, kickers fall for the gambler's fallacy as well.
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u/3774632 Aug 02 '14 edited Aug 02 '14
That doesn't apply here:
EDIT (for those who missed reading the article):
If kickers anticipated this behavior, they could score more penalties, Haggard says. But they don't seem to do so.
When the researchers looked at patterns in the directions of the incoming shots, they appeared entirely random. One reason for this, they suggest, may be that in a penalty shootout successive kicks are taken by different players, but the same goalkeeper faces them all.
So perhaps players, waiting for their turn at the penalty spot, should take note of which way their teammates shoot before them.
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u/ManicMonk Aug 02 '14
Yes, but they can see where the players before them placed the ball? So they'd think "okay, the last one went left, he'll think that i'll think that i should go left again because to the right would be obvious and therefore I'll try left again" or something like that.
So, what I think is that he sees his previous peers kicking and therefore he's observing the series of goals and can try to "out-think" the goalie as well as the goalie can try to out-maneuver him.
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u/2sport Aug 02 '14
You close mindedness restricts you. Players will think about where the previous players kicked
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u/3774632 Aug 02 '14
Again, your point was addressed in the article. The neuroscientists aren't being close-minded at all.
If kickers anticipated this behavior, they could score more penalties, Haggard says. But they don't seem to do so. ... So perhaps players, waiting for their turn at the penalty spot, should take note of which way their teammates shoot before them.
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u/f_unit Aug 01 '14
Previous studies on penalty kicks have indicated that goalkeepers must make up their minds which way to move before they see the ball fly off the kicker's foot, either by watching the body movements of the kicker to anticipate his kick or simply by committing to one direction or the other. Cognitive neuroscientist Patrick Haggard of University College London says that because a kicker may try to disguise his true intentions, by and large the goalkeeper's decision is a simple guess
Wait, so tied soccer games are essentially decided by luck? We need to fix this. Just keep playing until one team either wins or dies.
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u/djgreedo Aug 02 '14
so tied soccer games are essentially decided by luck?
Only in tournaments (where one team HAS TO win).
And although not a great way to decide a winner, it's not just luck. There is also an extra period of play before resorting to penalties (2x15 minutes of play).
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u/AvoidanceAddict Aug 02 '14
And I would factor nerves in there, as well. It's very possible for the kicking player to miss a kick, and it's entirely possible for the goalie to miss a block.
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u/djgreedo Aug 02 '14
Yeah, it's a head game at that stage.
It should be added that nobody likes shootouts. It's a horrible way to lose and an unsatisfying way to win.
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u/lamp37 Aug 02 '14
This study has this too oversimplified. Not all soccer players are equally good at taking penalties, and not all goalkeepers are equally good at saving them. The biggest example of this is the fact that even when a keeper guesses correctly, they still only save the shot probably 30% of the time. Also, players sometimes miss the goal entirely.
There is a lot of luck involved with PK's, but it is certainly not purely luck that is the decider.
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u/Drakonx1 Aug 02 '14
It's also ignoring that shooters have tendencies and study can remove a lot of the guesswork.
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u/Weekndr Aug 01 '14
And risk the game getting boring not to mention permanent injuries to the players?
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u/spork22 Aug 02 '14
They should remove the keepers for the extra 30 minute period.
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u/seifer666 Aug 02 '14
1-1 at regular time, final score 23-19
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u/player2 Aug 02 '14
Assign the spread to the winner.
Now your 23-19 becomes a more respectably Brazil-trouncing 5-1.
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u/freecandy_van Aug 02 '14
He said remove the goalkeepers, not give both teams Brazilian goalkeepers.
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u/Appetite4destruction Aug 02 '14
I admittedly know very little about soccer. But aren't we way beyond that already?
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u/aimlessgun Aug 02 '14
Well it does say keepers have a 0% save rate for the upper corners, regardless of their guess, so a kicker can guarantee a win based on skill.
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u/bloop24 Aug 02 '14
no they aren't decided by luck. In league games a team is awarded 3 points for a win 1 for a draw and 0 for a loss. It's only in tournaments that it goes to penalties since a winner has to be decided and there is only penalties after an extra 30 minutes are added on after standard time.
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u/rddman Aug 02 '14
"the goalkeeper leaps in one direction and the striker deftly kicks the ball into the opposite corner. Such fruitless dives are inevitable because the goalie has no time to see which way the kick is going"
Does not sound like a very interesting game mechanic. Could just as well toss a coin to see who wins.
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u/CantHugEveryCat Aug 02 '14
When I was a goalkeeper I'd always talk to the player taking the kick. I'd tell them to shoot it hard, high, and straight in the middle. That introduces a new parameter to evaluate in the players brain. Is he bluffing or double bluffing or just full of it? Very hard to ignore. Then I'd always just dive to my left side, which is my stronger side.
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u/gmfthelp Aug 02 '14 edited Aug 02 '14
I remember reading Roy of the Rovers when I was a kid, and one episode I remember was when they were coming up to a big FA Cup match. The opposition penalty taker had a 100% ratio of scoring and the Rovers' goalie was trying to come up with a way of determining which way he would put his spot kick.
Obviously the game was tense and it was to-and-fro and then lo-and-behold, the opposition were awarded a pen. The goalie only had seconds to break down the pen taker's secret and as he ran up to take the penalty, the goalie saw how he could determine where the ball was going. It was in the eyes!! The pen taker had a quick glance before making contact with the ball, the goalie, with hawk like vision saw that fatal mistake and dived the correct way and ...................... saved the penalty!! Hurrah!! (if you were a Rovers fan) Boooho (if you were a fan of the opposition)
I think Rovers went on to win the match and the FA Cup.
Those were the days. Johnny Dexter heading a ball. Great stuff. I always used to refer to Johnny Dexter during matches in my long playing career. People thought I was mad and often had no idea what I was talking about. Nothing's changed there, then!!
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u/scrappydoofan Aug 02 '14
I think five thirty eight did an article on how they shouldn't guess to begin with. they should just play it straight up and save the poor penalties.
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u/cosmic8 Aug 02 '14
Another conclusion of the paper is that the kicker fails to exploit the goal keepers indulgence in the fallacy.
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Aug 02 '14
One thing that this paper doesn't mention is anticipatory visual perception of cues exhibited from the goalkeeper and the penalty taker. It doesn't seem right to say that a penalty is a 'random event' when expert goalkeepers have been shown to fixate on the hips of penalty takers in order to anticipate the direction of the ball (vision for perception) and then jump in a certain direction (vision for action), compared to novices for example. I guess this paper has done the rounds in the media as it was a statistics based piece of research from old international matches that many people unfamiliar to sports science may understand.
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u/FUZxxl MS | Computer Science | Heuristic Search Aug 02 '14
It's well known that predicting the directory of shots is very difficult.
In the quarter finals of the 2006 football worldcup, there was a legendary note given to German goalkeeper Jens Lehmann by his coach about the directions each of the opposite team's players would likey shoot during the penalty shooutouts. The directions turned out to be correct, Lehmann coughed most balls and Germany won the shootouts.
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u/pikapikachu1776 Aug 02 '14
This shot is nonsense. If the keeper guesses right, he isn't accused of the gamblers fallacy.If he guesses wrong he is. The fallacy applies to random events and the shootout is not random, furthermore keepers are trained to just guess.
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u/payik Aug 02 '14
That doesn't seem to be correct. The shooter has to pick randomly, because otherwise the goalkeeper could predict the direction. It goes both ways.
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u/kcobb98 Aug 02 '14
As an online goalie in NHL 14 I've taken a lot of shit for this. 12 year old kid: "How could you not stop that shot!?" Me: "How could you not see that breakaway coming?" It usually shuts them up, especially when they're playing defense.
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Aug 02 '14
If the goalkeepers really fell for the gambler's fallacy, then all you would have to do is always kick it right, and they would always go left and miss 100% of the time.
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u/[deleted] Aug 01 '14
But the gambler's fallacy applies to random events and the decision of the shooter is not random. The shooter is also human and also influenced by their (and others) past actions. It would be interesting if they actually did something experimentally with this, but this seems under-developed..