The text was the first 3,200 words of The Case of the Velvet Claws, a detective novel by Erle Stanley Gardner. Seventy-three undergraduates read it alone at a computer, one word at a time, pressing the space bar to bring up the next. Four times a screen interrupted to ask whether, just before it appeared, their attention had been on the story. At the end came eight questions about the plot.
The reading was the second half of the study. The first half was about errands.
Each student had been randomly assigned to one of three groups. In the first, they described two important tasks or errands they needed to finish in the next few days, ones that weren’t part of their routine and that they didn’t yet know when, where or how they would do. The second group described the same kind of tasks and then made plans for them, in detail: how, when and where. The third group described two tasks they had already finished.
Four students guessed that the two halves were connected and were left out, leaving 69.
The students with unfinished tasks reported being more distracted by thoughts of those tasks while they read. They also answered fewer plot questions correctly: 6.13 out of 8 on average, against 6.93 for the group whose tasks were done. Among them, 65.2 percent reported their mind wandering at least once, compared with 33.3 percent of the students who had made plans.
The planners were the surprise. Their errands were just as undone as the first group’s. Yet they reported no more intrusive thoughts than the students whose tasks were finished, and they answered 6.94 questions right.
The psychologists behind the study, E. J. Masicampo and Roy Baumeister of Florida State University, ran the same idea several ways and published the results in 2011. In one study, 97 students were told in advance about a brainstorming task they would do at the end of a session. Those who had committed to a specific plan for it solved more anagrams in an unrelated task beforehand, 9.55 on average, than those who knew about the task but had no plan, who solved 6.55. The effect depended on how earnestly the plan was made. “Those who ultimately executed their plans,” the authors reported, “were those who also exhibited no more intrusions.”
“Once a plan is made,” they wrote, “the drive to attain a goal is suspended.” The errands were still waiting. They just had a time and a place now.