One factor that makes cognitive psychology such a difficult topic to study is that people have many ways of approaching the same problem. A student trying to solve a geometry problem might attempt to remember a formula related to that problem or to think of another problem similar to the one being solved at that moment or to draw a diagram. To make matters more difficult, the same person may try many different strategies when solving a set of problems (or even within a single problem).
But, this flexibility is also interesting. What processes enable us to switch between strategies? Clearly, there are benefits to being able to use many strategies to solve problems. Are there costs as well?
A paper by Ryan Hamilton, Kathleen Vohs, Anne-Laure Sellier, and Tom Meyvis in the May, 2011 issue of Organizational Behavior and Human Decision Processes explores the costs of switching strategies.
These authors point out that we have many broad mindsets that we can use to solve problems. For example, in other blog entries, I have talked about construal level. Sometimes we solve problems by thinking about them abstractly, while at other times we solve problems by thinking about them concretely. They argue switching between abstract and specific ways of thinking about problems requires self-control resources.
Research on ego depletion by Roy Baumeister, Kathleen Vohs, and their colleagues suggests that when you exert a lot of self control at one time, it can make it more difficult to exert self-control again later. The idea is that self-control is a limited resource that takes time to rebuild.
So, to explore whether switching problem solving mindsets involves self-control resources, Hamilton, Vohs, Sellier, and Meyvis put people in a situation in which they had to switch strategies and then looked to see whether that affected later situations that would require self-control.
One study used construal level as a mindset. Some people were asked to answer a series of questions about why they would carry out a series of actions. Research by Antonio Freitas, Peter Gollwitzer, and Yaacov Trope shows that answering why questions makes people think abstractly about the reasons and goals related to actions. Other people were asked to answer a series of questions about how they would carry out a series of actions. These how questions make people think specifically about what is required to achieve a goal. A third group answered a group of why questions and a group of how questions, and so they had to switch mindsets during the study.
After answering questions, people did what they thought was an unrelated study that was focused on testing a bitter but healthy drink that participants were told is popular in Japan. People earned a nickel for each small cup of the drink they finished. Because the drink had an unpleasant taste, it took some self-control to drink it. The participants who answered only how or why questions drank about three times as much of the drink as those who had to switch between how and why questions. This result suggests that switching mindsets required self-control.
An impressive aspect of this research paper is that the experimenters present five studies. Each one uses a different type of mindset. For example, another study had bilingual participants either answer questions in one language or switch between languages. A third experiment had people try to perform a task by maximizing the number of points they gained, minimizing the number of points they lost or switching between maximizing points gained and minimizing points lost.
The measures of self-control used later involved things like maintaining physical exertion, or keeping a straight face while watching a funny video. In each study, people who had to switch between mindsets led to worse performance on the later self-control task compared those who could maintain a single mindset.
This work suggests that there is a mental consequence to hard thinking. When you spend a day working on hard problems you are likely to have to switch the strategies you use many times. Each of those switches carries a cost with it. You are taxing a resource that may be limited. Over time, your ability to switch strategies itself may be affected, because you will have tapped out that resource.
If you have been working on hard problems all day, and you find yourself stuck, it may be a good idea to walk away from the problem for a while. There are many good reasons to let a problem rest when you reach an impasse. This research suggests that giving yourself a break may help you to recoup the self-control resources that you spent on earlier thinking.
Finally, remember that after a long day of hard thinking you should try to avoid other stressful situations. When your self-control is depleted, there is lots of evidence that you may react more aggressively towards others than you might if your self-control is intact. So, be aware that after a long hard day of thought you might be grouchier than normal.