Research suggests people underestimate numerical guesses when leaning left

To test for such an odd thing, the team enlisted a group of 91 volunteer undergraduate students and asked each of them to make estimations about some random things they didn’t actually know the answers to, while standing atop a Wii balance board.

In the first such experiment, a subset of the volunteers were asked to make estimations based on things they could envision in their mind, such as building height or a city population. The second group were asked to make guesses about more fuzzy type things such as how many grandchildren did Queen Beatrix have, using a scale of 1 to 10.

While making their estimates, the volunteers were asked to stand on a Wii balance board and to maintain a straight posture as indicated by a crosshair on a computer screen. What they didn’t know was that the posture meter had been rigged so that some were pushed slightly left, others slightly right, with the rest standing straight up and down. For both experiments the groups were split into six groups with the only changes being the order of the questions asked and the induced posture.

After the experiments were concluded, the volunteers were all asked to complete another questionnaire to find out if they actually knew any of the answers or if they were aware that their posture had been altered. As it turned out, none knew any of the answers, which means all the answers given were true estimates, and none caught on to the fact that their posture had been altered.

After studying the results, the research team found that virtually every answer given by those leaning left was smaller than those leaning right or standing straight upright. As an example, those leaning left gave estimates of the height of the Eiffel Tower that were 12 meters shorter on average than the other two groups.

The study shows, the team reports, that our bodies impact our minds in ways that most of us are completely unaware of and as a result decision-making might be skewed in ways that might surprise us.

More information: Leaning to the Left Makes the Eiffel Tower Seem Smaller, Psychological Science, Published online before print November 28, 2011, doi: 10.1177/0956797611420731

Abstract
In two experiments, we investigated whether body posture influences people’s estimation of quantities. According to the mental-number-line theory, people mentally represent numbers along a line with smaller numbers on the left and larger numbers on the right. We hypothesized that surreptitiously making people lean to the right or to the left would affect their quantitative estimates. Participants answered estimation questions while standing on a Wii Balance Board. Posture was manipulated within subjects so that participants answered some questions while they leaned slightly to the left, some questions while they leaned slightly to the right, and some questions while they stood upright. Crucially, participants were not aware of this manipulation. Estimates were significantly smaller when participants leaned to the left than when they leaned to the right.

Journal reference: Psychological Science

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