Understanding why this is the case can illuminate a range of experiences, including something as far removed from voluntary calorie restriction as the ordeal of outright poverty.

Imagine that you are attending a late-afternoon meeting. Someone brings in a plate of cookies and places them on the other side of the conference table. Ten minutes later you realize you’ve processed only half of what has been said.

Why? Only half of your mind was in the meeting. The other half was with the cookies: “Should I have one? I worked out yesterday. I deserve it. No, I should be good.”

That cookie threatened to strain your waistline. It succeeded in straining your mind.

This can happen even with no cookie in sight. Dieters conjure their own cookies: psychologists find that dieters have spontaneous self-generated cravings at a much higher rate than nondieters. And these cravings are not the dieters’ only distraction. Diets force trade-offs: If you eat the cookie, should you skip the appetizer at dinner? But that restaurant looked so good!

Many diets also require constant calculations to determine calorie counts. All this clogs up the brain. Psychologists measure the impact of this clogging on various tasks: logical and spatial reasoning, self-control, problem solving, and absorption and retention of new information. Together these tasks measure “bandwidth,” the resource that underlies all higher-order mental activity. Inevitably, dieters do worse than nondieters on all these tasks; they have less bandwidth.

One particularly clever study went further. It tested how dieters and nondieters reacted to eating a chocolate bar. Even though the bar provided calories, eating it widened the bandwidth gap between dieters and nondieters. Nondieters ate and moved on, but dieters started wondering how to make up for the calories they had just ingested or, even more fundamentally, pondered, “Why did I eat the bar?”

In other words, diets do not just strain bandwidth because they leave us hungry. They have psychological, not just physiological, effects.

The basic insight extends well beyond the experience of calorie counting. Something similar happens whenever we make do with less, as when we feel that we have too little time, or too little money. Just as the cookie tugs at the dieter, a looming deadline preoccupies a busy person, and the prospect of a painful rent payment shatters the peace of the poor. Just as dieters constantly track food, the hyper-busy track each minute and the poor track each dollar.

As Prof. Eldar Shafir at Princeton University and I argue in our new book, “Scarcity: Why Having Too Little Means So Much” (Times Books), a similar psychology of scarcity operates across these examples but with varying degrees of force. If a cookie can tax our mental resources, imagine how much more psychological impact other forms of scarcity can have.

Take the case of poverty. In a paper published last month in Science, with Profs. Anandi Mani at the University of Warwick and Jiaying Zhao at the University of British Columbia, Professor Shafir and I waded into politically charged territory. Some people argue that the poor make terrible choices and do so because they are inherently less capable. But our analysis of scarcity suggests a different perspective: perhaps the poor are just as capable as everyone else. Perhaps the problem is not poor people but the mental strain that poverty imposes on anyone who must endure it.

One of our studies focused on Indian sugar cane farmers, who typically feel themselves to be both poor and rich, depending on the season. They are paid once a year at harvest time. When the crop is sold, they are flush with cash. But the money runs out quickly, and by the time the next harvest arrives they are stretched thin: they are, for example, 20 times as likely to pawn an item before harvest as after it. Rather than compare poor and rich farmers, we compare each farmer to himself: when he is rich against when he is poor. This kind of comparison is important because it addresses valid concerns that differences in psychological tests merely reflect differences in culture or test familiarity.

Sendhil Mullainathan is a professor of economics at Harvard.

Article source: http://www.nytimes.com/2013/09/22/business/the-mental-strain-of-making-do-with-less.html?partner=rss&emc=rss