Where has your willpower gone?

New Scientist Jan. 28 - Feb. 3, 2012
"Where has your willpower gone?" by Roy F. Baumeister

Children with stronger self-control at age 4 grew up to be more successful in school and work, and to be more popular.

Research has shown repeatedly that after people exert self-control, they tend to perform relatively poorly on a subsequent seeming irrelevant test of self-control. It appears that "energy" was consumed and depleted during the first test, leaving less for more challenges.

In a study of German adults who wore beepers, for a week, and reported what they were doing when the beepers went off, it was found that people spend 3 - 4 hours a day on average just resisting temptations and desires.

"as the day wears on, the more often the person exercises self-control to try to resist what they desire, the more likely they are to give in to whatever temptation comes along: it's not the time of day that matters, but the cumulative exertion that saps your willpower."
"after exerting self-control, people perform worse on the next self-control task without being given glucose between tasks."
"In order to resist tempting foods, we need willpower but to have willpower, we must eat."

They also mentioned a study of parole judges in Israel:

http://economix.blogs.nytimes.com/2011/04/14/time-and-judgment/

April 14, 2011, 10:00 am

Up for Parole? Better Hope You’re First on the Docket
By BINYAMIN APPELBAUM

A new paper finds that experienced parole judges in Israel granted freedom about 65 percent of the time to the first prisoner who appeared before them on a given day. By the end of a morning session, the chance of release had dropped almost to zero.

After the same judge returned from a lunch break, the first prisoner once again had about a 65 percent chance at freedom. And once again the odds declined steadily.

The reason offered by the authors suggests the broader significance. They write that making successive decisions depletes a limited mental facility, just like curling a dumbbell wears out your arms. As people get tired, they look for shortcuts, and one of the easiest shortcuts is to uphold the status quo –- in this case, denying parole.

[...]

“I don’t think this is at all unique to judges,” one of the authors, Jonathan Levav of Columbia University, said in a radio interview with the PRI program “The World.” “I think you would find the same thing with doctors or with admissions officers or with funding decisions. In fact the interesting thing is that pilots have all these checks and balances, they have all these checklists that they use exactly in order to overcome fatigue. So some fields have a sensitivity to the fact that people can get tired on the job, whereas in other fields it seems like the expert is just there, you know, in a room for 12 hours in a row and break be damned.”

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