The best time to ask someone for a favour is at least several weeks in advance, a new study suggests. The research finds that people consistently over-commit because they expect to have more time in the future than they do right now.

Previous studies have shown that people generally “value things less in the future than now”, says Gal Zauberman, a consumer-behaviour researcher at the University of North Carolina in Chapel Hill, US. For example, many people prefer to pay for something in a week’s time rather than today – even if it costs slightly more.

Now, Zauberman and colleague John Lynch at Duke University in Durham, North Carolina, have found that this tendency is even stronger for time than for money.

“When asked to do something far in the future, we usually say ‘yes’. Sure, I’ll be happy to help you write a paper or move apartments,” Zauberman said. “People always like to delay things, but they are more optimistic about changes in time than in money.”

The researchers came to their conclusions after giving groups of students a range of questionnaires. In one questionnaire, for example, the students were asked how much spare time and spare money they had that day and how much they expected to have in a month. The students believed both resources would be more available in a month’s time, but they believed more strongly that they would have more time in the future.

That suggests people gauge their financial situations better than their schedules. “Barring some change in employment or family status, supply and demand of money are relatively constant over time, and people are aware of that,” the researchers report.

More here.