Posts Tagged ‘sports psych’

Return of the “hot hand” in basketball?

October 10th, 2011

Just noticed a new study on a very old debate: the “hot hand” in basketball. There was a very famous study back in 1985 that concluded that our belief that players have hot streaks and cold streaks is simply an example of the “clustering illusion.” Think of it this way: if you flip a coin over and over, you’ll occasionally have streaks of six or seven heads in a row — but the probability of the next toss is still 50-50. What Gilovich, Vallone and Tversky found when they analyzed NBA game data was the same pattern: the probability of hitting a given shot was independent of whether the player had hit or missed his previous attempts.

Of course, most people simply refuse to acknowledge this sort of result that conflicts with what seems “obvious.” As Tversky noted:

I’ve been in a thousand arguments over this topic, won them all, but convinced no one.

After all, we can all remember, say, Michael Jordan taking over a game in the fourth quarter and pouring in basket after basket. But part of this may be because, with the game on the line, he starts taking more shots. And we tend to forget all the nights when he didn’t manage to take over the game, despite presumably making the same effort. This is one of those issues when we can really only trust the cold, hard data.

Anyway, the new study (full text freely available here; press release here) takes advantage of the Moneyball era of statistical abundance to revisit this question with a larger data set. The researchers, from Yale, looked at every free throw taken in the five seasons between 2005 and 2010 — a staggering total of 308,862 free throws — and tried to determine whether the patterns in the data could truly be explained by considering each shot as an independent event. And indeed, they found some evidence that — according to the press release, at least — supports the existence of the hot hand.

The key result they found is that, when players were taking two foul shots, they had a slightly greater chance of hitting the second shot when they hit the first (~76%) compared to when they missed the first (~73%). There are two possible ways to explain this:

  1. Players have periods when they’re “hot” and “cold.” The success of the first free throw is an indicator of which of those zones (if any) they’re in for the second throw.
  2. The outcome of the first throw causally influences the outcome of the second throw. For example, if you hit the first, you relax, feel confident, and drain the second; if you miss the first, you tense up, feel the pressure, and (become infinitesimally more likely to) miss.

The researchers argue against that second explanation, for the following reason. When they analyzed the individual data, some players shot better after hitting the first throw, while others shot better after missing the first throw. This is to be expected: since the supposed effect is psychological, different players will react differently to hitting/missing the first throw. But when they drilled deeper and broke the data down into individual seasons, they found that players who shot better after hitting the first shot in one season had a 50-50 chance of showing the opposite pattern the next season. That suggests that the connection between the first and second shots isn’t actually causal.

So what does this all mean? Well, in a sense it makes a fairly obvious point. It would be ludicrous to imagine that pairs of free throws are totally uncorrelated — consider, say, a pair of throws taken late in an insignificant game where the outcome is already decided, just after returning from a prolonged injury and having sustained a hard foul that hurts your shooting hand, the night after a coast-to-coast flight that was delayed by weather for seven hours, during which you got hammered because one of your teammates was celebrating his 21st birthday. The probability of both those throws will be slightly lower than a pair of throws under optimal conditions — and that leaves the kind of statistical footprint detected in this paper.

In a sense, of course, that’s precisely the point: under those conditions, you might say the player has a “cold hand.” But that’s not usually what we think of when we talk about hot and cold hands — we’re usually referring to time frames that are longer than two back-to-back free throws (it usually takes more than two shots before announcers start pulling out the “hot hand” trope), but far shorter than game-to-game variations. So in the end, I’m going to keep believing that the hot hand doesn’t exist until better evidence emerges.

New explanations for runner’s high

February 17th, 2011

Gretchen Reynolds has an article in the New York Times about recent research into the origins of “runner’s high,” suggesting that endocannabinoids rather than endorphins might be responsible — in other words, the body’s internal version of marijuana instead of morphine:

But perhaps the most telling experiment was published last year by researchers in France who had bred mice with no functioning endocannabinoid receptors. Mice usually love to run, but the genetically modified animals, given free access to running wheels, ran about half as much as usual.

Reynolds is usually an excellent reporter, but I was a bit disappointed in the lack of context offered in this article. She dismisses the role of endorphins as follows:

Endorphins, however, are composed of relatively large molecules, “which are unable to pass the blood-brain barrier,” said Matthew Hill, a postdoctoral fellow at Rockefeller University in New York. Finding endorphins in the bloodstream after exercise could not, in other words, constitute proof that the substance was having an effect on the mind.

This is true, but German researchers published a study back in 2008 that was very widely reported (including in the Times by Reynolds’s colleague Gina Kolata) that directly measured the increase of endorphins in the brain after a two-hour run. Both Reynolds and Hill are undoubtedly familiar with this study, so it seems disingenuous to pretend that we don’t know anything about the link between exercise and endorphins in the brain.

Ultimately, the runner’s high is such a nebulous, ill-defined thing, meaning different things to different people, that it’s probably a combination of several different effects — endorphins, endocannabinoids, and perhaps other factors, including some straightforward psychological ones. So it seems silly to dismiss the “old” theory in favour of a new one when there’s no reason the two can’t coexist.


Training three times a day: it’s mental

October 4th, 2010

It was a good day at the pool for Canadian swimmers today. More specifically, it was a very good day for swimmers who train with coach Randy Bennett at the Victoria Swim Academy in B.C. Not only did Ryan Cochrane pick up the country’s first gold, in the 400m free; clubmates Julia Wilkinson and Stefan Hirniak picked up bronzes in the 200m IM and the 200m butterfly, and two others from the same group swam in finals — all this on the first day of competition at the Commonwealth Games in Delhi.

So what’s the secret? Hard work, obviously — but not just of the physical kind. After the race, Hirniak talked about a five-week stint of three swim workouts a day over the summer, and how the benefits were as much mental as physical:

I don’t think I would have paid much attention to that kind of comment a few years ago. But the more I read about the latest research into the nature of fatigue and limits of human performance, the more inclined I am to think Hirniak is right on the money with what he says here.

On an unrelated note, I was chatting with one of the Swimming Canada officials about the sports science team they’ve brought with them to Delhi. It’s an impressive contingent, including a couple of physiotherapists, a couple of physiologists, and a couple of biomechanics experts who are filming every lap of every race and producing a rush analysis for the swimmers and coaches every evening. I’m hoping to have a chance to hang out with some of these guys over the next week and find out more about what they’re doing.

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The psychology of choking

September 21st, 2010

I interviewed University of Chicago psychologist Sian Beilock for this Globe and Mail article about “attentional focus” and athletic performance last year. She’s an exceptional researcher — her name comes up repeatedly when I’m interviewing other researchers, usually along the lines of “You should talk to Sian Beilock, she’s a genius and her research is fascinating.” She’s the one who did the study showing that expert golfers putt better when they’re distracted, while novices putt better when they focus — a finding that has been replicated in a wide variety of tasks.

I mention all this because Beilock’s new book, Choke: What the secrets of the brain reveal about getting it right when you have to, was released today. She’s widely considered the world’s foremost expert on choking — and, needless to say, her research has a lot to say about how not to choke. I’m looking forward to reading the book. And in the meantime, she’s also blogging on the topic for Psychology Today.

“Defensive pessimism” and athletic performance

September 21st, 2010

When I first started competing in running races, I used to look around at the other runners while I was warming up and think, “Oh man, that guy looks fast… and that guy too… and that guy…” Gina Kolata has an article in yesterday’s New York Times about this kind of thinking as she and her husband tried their first ever bike race:

The way we started thinking when we saw the other cyclists is a strategy called defensive pessimism, said John S. Raglin, a sports psychologist at Indiana University. He explained that it consisted of “downplaying your ability and expectations.” That way, if you do poorly you are not crushed, and if you do better than you expected, “you get this payoff,” Dr. Raglin said.

He has done studies of track-and-field college athletes who employ the defensive pessimism strategy, comparing them with optimists who think they’ll do well. The pessimists performed just as well as the optimists.

I’d like to read more about this, because it’s a tactic I’ve made heavy use of (to the point that teammates sometimes didn’t like being around me before big competitions because I was such a downer!). On the other hand, recent research by people like Samuele Marcora emphasizes the role of the brain in determining how far you can push yourself, so you’d think positive thinking would be pretty important.

As Kolata points out, these kinds of thoughts aren’t relevant only in competitive settings:

On the other hand, the type of anxiety we felt when we saw the other riders is also a reason many people steer clear of competitive sports altogether — even a reason many avoid walking into gyms, said Ralph A. Vernacchia, director of the Center for Performance Excellence at Western Washington University.

“What you are looking at is a social comparison,” he said.

Like just about anything, I suspect there’s an optimal level of “defensive pessimism” beyond which it becomes truly counterproductive. These days, when I’m feeling nervous before a race, I try to turn these pessimistic thoughts into a joke to minimize their power — or at least, I say them out loud so that it’s obvious how silly they sound. “That guy looks really fast… and so does that little girl… and so does that old guy pushing his grandchildren in the jogging stroller…”

(I realize, of course, that there are many little girls and old guys pushing their grandchildren in strollers who really are very fast. My point is just that it’s silly to judge and get scared based on appearances alone. And the true peace of mind, especially in a recreational setting, comes when you understand that it’s okay if the little girl does beat you — the point is to go as fast as you can, and not worry about what others are doing. But that’s sometimes easier said than done.)

Jockology: training for soccer

June 24th, 2010

This week’s Jockology column rounds up a bunch of research on the optimal preparation and training for soccer: the mechanics of kicking, the physiology of repeated short sprints, the psychology of penalty kicks, the optimal warm-up and nutrition, rapid direction changes, etc. It’s in the form of a big infographic, put together by Trish McAlaster, the talented artist I often work with at the Globe. (We’re currently working a pretty cool graphic for the next column — stay tuned!)

Most interesting bit of info in the current column, for me, was this: when you run a short sprint, you get about 20% of the ATP you need from aerobic processes, and 80% from anaerobic processes. But if you keep sprinting (as you would for a soccer game), the third sprint is already 50% aerobic/50% anaerobic, and the “Nth” sprint is 75% aerobic/25% anaerobic. So if you want to be fast late in the game, you need to fuel yourself like an endurance athlete.

(This info comes from Stuart Phillips‘ chapter in the book Sports Nutrition: From Lab to Kitchen. And I actually simplified the info a bit for the column by combining the contributions from phosphocreatine with other anaerobic sources. The actual split for aerobic/anaerobic/phosphocreatine is 20/30/50 for the first sprint, 50/20/30 for the third, and 75/5/20 for the Nth.)


Crossing your fingers boosts performance (touch wood)

June 16th, 2010

Amby Burfoot points out a pretty neat study by German researchers in Psychological Science showing that superstition really does boost performance. The researchers point out that, despite their irrationality, superstitions are surprisingly prevalent across cultures, with famous examples such as Michael Jordan wearing his old UNC shorts under his NBA uniform for his entire career. And they’re particularly common in two groups “whose members regularly engage in performance tasks–namely, athletes and students.”

But do they work? The researchers did four studies that suggest they do. The first was a simple test: take ten putts on a golfing green and sink as many as you can.

[W]hile handing the ball over to the participants, the experimenter said, “Here is your ball. So far it has turned out to be a lucky ball” (superstition-activated condition) or “This is the ball everyone has used so far” (control condition).

Sure enough, the lucky ball group hit 6.42 putts, while the neutral ball group hit just 4.75.

The other three experiments involved motor dexterity, memory and anagrams, and the participants were primed with superstitions like keeping their fingers crossed or having a lucky charm present — all without realizing that the true purpose of the experiment was to test superstitions (anyone who figured it out was excluded from the analysis).

The upshot of the experiments is that superstition’s power appears to mediated through “self-efficacy” — basically, a positive superstition makes you believe you’ll perform better, and that confidence enables you to do so. The researchers point out that this is different from, say, bouncing the ball three times and exhaling loudly every time you take a foul shot. Those sorts of rituals serve to focus attention and trigger well-learned motor sequences, rather than boosting self-efficacy.

And, with respect to truly outstanding performances, [the authors conclude,] the present findings suggest that it may have been the well-balanced combination of existing talent, hard training, and good-luck underwear that made Michael Jordan perform as well as he did.

Soccer science

June 14th, 2010

When I went out for my run this morning, Sydney seemed like a ghost town: empty sidewalks, tumbleweed blowing down the streets, etc. The only signs of life were in the pubs, which had been open since 4 a.m. for the Socceroos’ Monday-morning World Cup debut. Inside, people were huddled quietly over their empty schooners, absorbing their 4-0 loss to Germany.

In that spirit, a couple of good recent articles on the science of soccer:

- Ross Tucker of The Science of Sport has started a series on the physiology of soccer. The first installment offers a good profile of what it takes to play a full game: running 10 to 15 km, including between 80 and 110 sprints, and so on. I had a chance to chat with Ross for a couple of hours last week for an upcoming article — a very interesting guy with lots of insight, as you can gather from the blog.

- A very thorough round-up of recent research on the psychology of the penalty kick, by Andrew Keh of the New York Times. As I write this, Ghana has just taken the first penalty kick of the tournament, scoring to defeat Serbia — but we’ll be seeing a lot more of these when we reach the elimination rounds. One of the most interesting observations:

Kick takers in a shootout score at a rate of 92 percent when the score is tied and a goal ensures their side an immediate win. But when they need to score to tie the shootout, with a miss meaning defeat, the success rate drops to 60 percent.

“This to me is the key finding of all our studies,” said Geir Jordet, a professor at the Norwegian School of Sport Sciences in Oslo who has analyzed shootouts with fervor. Jordet also found that shooting percentages tend to drop with each successive kick — 86.6 percent for the first shooter, 81.7 for the second, 79.3 for the third and so on.

“It demonstrates so clearly the power of psychology,” he said


Pacing, “deliberate practice,” and Jerry Schumacher

May 13th, 2010

In a post last month, I mentioned having a chance to chat with Simon Whitfield about his recent training camp in Portland with the Nike running groups coached by Alberto Salazar and Jerry Schumacher. This week’s Jockology column in the Globe and Mail explores some of the ideas Whitfield talked about — in particular the fact that the Portland groups are very precise in monitoring their training paces, and how that relates concepts in sports psychology like “deliberate practice”:

… The group Mr. Whitfield trained with in Portland included Simon Bairu of Regina, who earlier this month smashed the Canadian record for 10,000 metres by 13 seconds at a race in Palo Alto, Calif., running 27:23.63. Chris Solinsky, another member of the group, broke the U.S. record in the same race, and a third member of the Portland group also dipped below the old U.S. record.

“They’re so precise about their pacing,” Mr. Whitfield says. “We came home with the message that when a tempo run is supposed to be, let’s say, 3:05 [per kilometre] pace, then 3:03 pace is not a success. That’s a fail.”

Such precision may be daunting, but it’s a hallmark of “deliberate practice,” a concept advanced by Florida State University cognitive psychologist Anders Ericsson and popularized in recent books like Malcolm Gladwell’s Outliers: The Story of Success. The best way to master an activity is not simply to repeat it mindlessly over and over again, Dr. Ericsson argues, but to set specific goals and monitor how well you meet them.[READ THE FULL ARTICLE]

I also chatted to Lex Mauger, the lead author of a recent study on pacing in a 4-km cycling time-trial. The study showed that getting accurate pace feedback during a hard effort really does lead to better performances — something many athletes would have told you intuitively, but which had never been shown. In particular, pace feedback seems to be crucial in the early stages of a race, before you’ve settled into a rhythm.

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The science of home-field advantage

February 18th, 2010

In celebration of a couple of Canadian gold medals in Vancouver, this week’s Jockology looks at the science behind home-field advantage:

The biggest edge gold medalists Maëlle Ricker and Alexandre Bilodeau had over their Olympic opponents may have been from their brain chemistry rather than the roar of Canadian spectators at Cypress Mountain.

A series of studies over the past decade has debunked the long-held theory that home advantage stems primarily from external factors such as an enthusiastic crowd, a familiar venue, travel-weary opponents and officials whose calls are swayed by the crowd. While these factors can play a role, a more basic biological imperative may be at work, as athletes display an evolutionarily driven desire to protect their territory. [read on...]

There are a bunch of interesting studies on the topic, which dissect the role of crowds, stadiums, refs and so on. There’s a sidebar to the piece that doesn’t appear in the online version (not sure if it’s in the paper version), so I’ll reproduce it here:

Can fans influence the game?
A new study shows that sports teams have a “home advantage” even if there’s no one in the stands. But that doesn’t mean crowds don’t have an impact. A 2002 study in the journal Psychology of Sport & Exercise asked qualified soccer referees to make calls on games they watched on video, with the sound either turned on or off. The refs who could hear crowd noise called 15 per cent fewer fouls against the home team than those watching in silence.