At Thaler’s suggestion, they called the part of the brain that wants to do something “the planner” and the other part “the doer.” The “planner-doer” model became a highly influential way of approaching economics, and would later be credited with substantially helping to increase the rate at which Americans save.
Thaler and Shefrin’s fascination with behavioral economics had different origins for each of them. Thaler, who taught in the University of Rochester’s business school, became intrigued after a dinner party at his home, when guests implored him to take away some cashew nut hors d’oeuvres, lest they spoil their dinner. The classically trained economist in him wondered, “‘Well, if you’re rational, you simply choose to stop eating,’” at some optimal point, Shefrin explains. But guests felt helpless to do so. So Thaler “asked the question, ‘What’s going on in our heads, and why is it that people don’t behave rationally in these kinds of situations?’”
Shefrin, then in the economics department at Rochester, had his own “aha moment” as his wife, a dental hygiene faculty member, was working on a research project which sought to help people with eating disorders make better health care decisions. Shefrin started thinking about eating disorders as an extreme example of people not acting in their own long-term best interest, and decided he wanted to study how nonrational behavior played out in economics.
Before long, he and Thaler found each other and began a 15-year collaboration, which continued even as Shefrin moved to Santa Clara University in 1978 and Thaler moved on to Cornell University. One such collaboration was a 1986 study of Santa Clara University MBA students, designed to investigate how individuals think about money differently based on how they acquire it.
The study’s central question: Is the way a person spends or saves money dependent on the source of the money—a paycheck vs. a home or investment vs. a windfall inheritance—or is the total value of their wealth all that matters? The students in the survey were presented with three scenarios, all of which were equivalent from a financial perspective but differed in how those finances were described. The survey results showed that even though acquiring money in each scenario increased their wealth by precisely the same amount, students were much more willing to spend certain kinds of wealth (especially from their paychecks) and inclined to save a far greater portion of certain other types of wealth (especially future wealth from an inheritance).
“Our Santa Clara students were the first to provide evidence in a systematic way that said it really matters in what form you get your wealth,” said Shefrin. The power of that concept—a special case of a phenomenon called “mental accounting”—loomed large in the Nobel Prize committee’s praise for Thaler.