• Send to a friend
  • Print

One Bird, One Stone

Why You Might Use Something More When It Accomplishes Less

Research by Ayelet Fishbach

Ayelet Fishbach is associate professor of behavioral science and 2007–08 David W. Johnson Professor at the University of Chicago Graduate School of Business.

How do we choose the means—that is, the actions, objects, or other resources—with which we attempt to achieve our goals? New research suggests that these choices are partly determined by the extent to which available means are only good for the specific goal we hope to accomplish.

It seems obvious that it is always best to be able to do more, rather than less. Assuming that you have something that is useful for one purpose, it should be desirable to also make it useful for another purpose. Isn’t it always better to kill two birds with one stone?

Not always, according to recent research by University of Chicago Graduate School of Business professor Ayelet Fishbach, and coauthors Ying Zhang of the University of Texas and Arie W. Kruglanski of the University of Maryland. Yes, people often place a higher value on actions, objects, or other resources to the extent that those things can be used to satisfy as many goals as possible. However, that value is not necessarily what determines whether they will actually use those actions, objects, or resources to accomplish a particular goal.

In their recent study “The Dilution Model—How Additional Goals Undermine the Perceived Instrumentality of a Shared Path,” Fishbach and colleagues suggest that in order to anticipate what means people will use to achieve a goal, one must understand how instrumental people believe those means to be—that is, how effective they believe the means will be for achieving the goal. This turns out to involve more than just understanding whether a given means “works” for achieving a goal, since there may be many ways of accomplishing a goal that all get the job done. The study’s new insight is that we also care whether our desired goal is the only goal that the means can serve.

For example, consider a person who only rides a bicycle every morning for recreation. What happens if that person starts to work in a building along her daily bicycle route, such that her morning bicycle ride also doubles as her commute? It is hard not to think of the morning bicycle ride as especially valuable, because it now serves two important purposes in the rider’s life. Still, the next time the rider wants to get out “just for fun” on a weekend, is a bicycle ride going to have the same appeal as before? Will it be as effective for recreation, or will the bicycle’s new function as a commuting vehicle reduce its recreation potential?

Previous research has shown that people do indeed assign a higher value to a means that serves multiple goals because, in some circumstances, people get more “bang for their buck” from a particular action, object, or resource. They can use it to make progress toward all goals at once, like using a bicycle for commuting while having fun. However, the study finds that increasing the number of goals served by a single means can also reduce perceptions of the means’ effectiveness with respect to serving each individual goal. A bike ride used for recreation and commuting will thus be perceived as less effective for recreation than a bike ride only used for recreation, and will similarly be seen as less effective for commuting than a bike ride only used to get to work. Accordingly, when a person only wants to pursue one goal, he or she is likely to see the path that can only achieve the desired goal as more effective—and thus more appealing— than the “more valuable” paths which serve a wider range of goals.

Fishbach explains: “You may go to the gym to stay in shape, but the gym may also be a place to meet people, relax, or even watch television. Then, if all you want to do is stay in shape, you’re less likely to go to the gym, because the gym serves these other goals. Instead of going to the gym, you’re more likely to go jogging outside.

“The results are counterintuitive, because people should want the means that achieve the most goals and adding more functions to an object should make it more attractive,” notes Fishbach. “There’s no reason not to kill two birds with one stone, but our study suggests that people prefer to use a particular stone associated with a particular bird.”

The Dilution Effect
Previous research on human motivation has shown that as the number of goals attached to a single means increase, people are less likely to link that particular means to each individual goal. On the basis of this assumption, the authors propose a “dilution model” of goal pursuit, whereby adding goals to a single means reduces (or “dilutes”) its perceived effectiveness for meeting each goal, thus reducing the likelihood that a person will utilize the means when they are looking to achieve any one of the goals. The extent of the dilution depends on how different the goals are. The more different the goals, the more likely each one is to undermine the other’s association with the shared means. More similar goals are less likely to interfere with each other.

In their studies, the authors measure dilution by looking at how long it takes people to recognize that a means and a goal go together—that is, to recognize that one can be used to achieve the other. According to the dilution model, adding a goal to a given means makes it harder for people to recognize that the means can still be used to accomplish the original goal.

Fishbach and colleagues tested their model in six experiments, manipulating the number of goals connected to a given means and the goals’ distinctiveness, as well as directly manipulating the strength of the connection between the means and additional goals. The first two experiments showed the basic effect: When people see a given means as linked to more than one goal, people report that the means is less effective for accomplishing each individual goal. For example, participants in the first experiment considered articles about health benefits for aerobic exercise. The results show that when the means (exercise) was described as serving two goals (preventing heart disease and maintaining healthy bones), rather than one, it was seen as a less effective tool for achieving either one of the goals. The second experiment showed that the same effect can be obtained when people generate goals for a given means themselves, rather than having those goals given to them. For example, those who listed two goals for attending college (e.g., getting a good education and making friends), thought their college experience was less effective at achieving each of these goals compared with those who listed only one goal.

The third experiment showed that the perceived distinctiveness of goals affects the degree of the dilution effect. Participants in this study were asked to read a scientific essay describing two benefits of eating organic food: reducing consumption of chemicals and increasing nutrition from the food, and they elaborated on what made the two goals either similar or different. Those who considered the differences between these benefits believed organic food is less effective for achieving each one, compared with those who considered the similarities between these benefits.

The fourth and fifth experiments showed that as an additional goal becomes associated with a given means, people become slower to link the means to its original goal.

“When we measured the strengths of association between means and goals, we found that when we added more goals, the means just doesn’t bring the original goal to mind,” explains Fishbach. “Adding goals slows down the time for recognizing the connection between the means and the goals.”

It is this slower, weaker association that explains the dilution effect—it is what reduces the extent to which people think of the shared path as effective for achieving the original goal. Thus, when a recreational bicycle becomes a commuting vehicle, seeing the bicycle is less likely to quickly remind you of “having fun,” because your mind also has to remind you that the bicycle can be used to get to work. As a result, the bicycle’s “fun” powers are diluted.

In the sixth experiment, the authors measured actual means choice by allowing people to choose a regular office pen or a combination laser pointer/pen for the goal of writing. As expected, the pen that served two goals (writing and laser pointing), rather than one, was less likely to be chosen. The laser pointer function for the combination pen diluted the perception that the pen was instrumental for the single goal of writing, making it less likely to be used than the regular pen.

“We found that people don’t choose to use objects that serve more than one goal if they only have one goal in mind,” says Fishbach.

What Will People Really Use?
Zhang, Fishbach, and Kruglanski’s study indicates that contrary to conventional belief, the preference for a given action, object, or resource may not always rise with the number of goals it serves.

“People often choose a particular object that does it all, but then use an object that is only good for a very specific goal,” says Fishbach. “My guess is that if I could buy two pens, one with two additional functions and the other that was only a regular pen, I would buy the multifunctional pen, and then discover that I’m less likely to write with it. There is a discrepancy between what we think will be useful and what we actually use.”

If you need something to satisfy multiple goals at once, such as needing a pen that you can use as a pointer while giving a PowerPoint presentation, multifunctional means may indeed be best. If, however, you’re looking to satisfy just one primary need at a time, Fishbach suggests that you avoid the temptation of multipurpose items and keep it simple. You are likely to get more use out of the things that do less.

“The Dilution Model: How Additional Goals Undermine the Perceived Instrumentality of a Shared Path.” Ying Zhang, Ayelet Fishbach, and Arie W. Kruglanski. The Journal of Personality and Social Psychology, 2007.