Home Court Advantage

Ah, but the courts aren't the same. Basketball is a visual game. The geometry of lighting and bleachers and building architecture surrounding the floor is not part of the court that is regulated by the rules of the game, but it nonetheless makes up the background visual field. Players may not realize they use this in their play. But I suspect they do.

Side story: I once had a cat that enjoyed running around the room, taking a flying leap off the back of a loveseat, and then onto the top of a bookshelf. One day, it did this after I had vacuumed, and obviously had not oriented the loveseat exactly in its former position. The cat's leap peaked about three inches short of the top of the bookshelf, against whose side the cat fell, and thence to the floor, in great embarrassment. It wasn't that the leap was too far, or that the cat couldn't see where it needed to leap. The cat easily made the leap a bit later, because it paid attention. But that cat's brain held an old map of the room. And the map isn't the territory. ;-)

Traditional NBA "wisdom" has held that the discrepancy is most explainable by variation in the way officials call the game, favoring the home team. This view is frequently supported by stats that show significant discrepancies in fouls called and free throw attempts between the two sites in a playoff series. However, Rick Carlisle, newly hired coach of the Dallas Mavericks, on ESPN radio this morning argued that this traditional wisdom is incorrect, pointing to the detailed and comprehensive evaluation of officiating now conducted by the NBA, which essentially now evaluates and grades EVERY call, and vigilantly seeks to ensure that calls are consistent from player to player, quarter to quarter and venue to venue.

It is indeed a fascinating issue, and I think the brain-map idea of the familiar home floor and basket suggested by Russell is a good one. It correlates with the shooting woes experienced by NCAA tournament players in large arenas with very different backdrops to the basket than normally experienced. If accurate, there should be some shooting percentage data to bolster the case.

I think you would also have to look into which calls the referees choose to make and which they let slide and if there's any disparity in how this affects the home and visiting teams.

There's a sport psychology book (Cox, 1994) that presents a good summary of research on the home court advantage.
One of the more interesting hypotheses presented is by Varca (1980).

He proposed a hypothesis similar to yours, in which the audience induces two types of play in the home team and visiting team. According to the hypothesis, the audience induces an increased state of arousal in both the home and visiting teams. However, for the home team, increased arousal results in functional aggressive behavior. For the visiting team, increased arousal results in dysfunctional aggressive behavior.

Using collegiate basketball archival data, Varca's hypothesis was supported when he showed that home teams had more steals, blocked shots, and rebounds, while the visiting team had more fouls. There were no differences in field goal percentages, free-throw percentages, and turnovers, which do not involve aggressive interactions between players.

Also,since rebounds, steals, and blocked shots involve gross motor skills, and, gross motor skills are known to improve with very high levels of arousal, this further facilitates home team player's physical performance. While attempting to deal with this audience-induced, motor performance advantage, the visiting team experiences an increased level of frustration, which triggers the dysfunctional aggressive behavior that ultimately leads to more personal fouls--all entirely consistent with the frustation-aggression hypothesis.

References

Cox, R.H. (1994). Sport psychology: Concepts and applications (3rd ed). Dubuque, Iowa: Brown and Benchmark Publications.

Varca, P.E. (1980). An analysis of home and away game performance of male college basketbal teams. Journal of Sport Psychology, 2, 245-257.

Wow, thanks so much for these responses! I'm definitely going to read that Varca paper.

It's probably multiply determined but I think conditioning may play a factor. Shepard Siegel has argued that drug tolerance is learned. He gave rats repeated doses of morphine (among other drugs) in one particular room (placebo in another room), and they developed tolerance. After tlerance developed, administer the drug in the placebo-associated room and they substantially lose the tolerance. Drug histories are identical--drug-opposite responses are triggered by the drug-associated room but not by the placebo-associated room.

Athletic training is similar to drug tolerance: run and get exhausted; continue to do it and you "develop tolerance" to that dose, so you increase it--run faster or farther. (Ditto for weight-lifting.) Play basketball in one room and get exhausted; but if it's a room we often play in, we produce responses that oppose the effect of the "drug," that bring us toward homeostasis. So at the end of the game the home team is less exhausted. And they win.

I just wanted to say that this conditioning hypothesis was suggested to me by a student who moved from Albany to Utica NY for school. He said he lifted weights in Albany, and when he came to Utica, he felt that the same weights were heavier. (I've tested this--unfortunately not well enough or long enough--and it didn't work, but I think conditioning is involved, anyway.)

When at home you own it all, the floor, lights, goals and
even the boundary lines. most of all the air you breath and
most of the fans who breath your air. when you do heroics
to catch a loose ball going out of bounds, its your people
who save the body from trauma. when you own the night and
everyone in the light, you own the game. it's mostly in the
heart.

A little correction there - home teams are 20-1 only in the semifinal second round so far. There were plenty of road wins in the first round: Orlando handily dismantled Toronto on their own court, Utah won multiple times in Houston, San Antonio veritably embarrassed Phoenix at home and Philadephia stunnered the veteran Detroit squad at the Palace on the first game of the series.

But to the mystique of home court advantage, I think what it does is give second tier players, rookies and such a boost of confidence. I'm skeptical Kobe or Garnett or LeBron play significantly better at home, even without the numbers in front of me. However, maybe someone like Delonte West or Luke Walton can heat up with that boost from the home fans, sleeping in their own bed the night before and having a sense of familiarity about them in their pregame routine. Once you get on the court, my thought is all that advantage priming is over with.

Teams do hire psychologists: They're called coaches.

to lish:

and that's where it counts.

Using collegiate basketball archival data, Varca's hypothesis was supported when he showed that home teams had more steals, blocked shots, and rebounds, while the visiting team had more fouls. There were no differences in field goal percentages, free-throw percentages, and turnovers, which do not involve aggressive interactions between players.

The neat thing about the NBA playoffs and 7 game series is that the best team will win no matter who has home court advantage. You may have an argument in the finals when two very evenly matched teams face each other, but when those two teams face each you have an argument in itself as to which team is the best. But the best team will win in a 7 game series.