Your Pupil Size Can Predict the Precision You Use to Make a Decision

How well do you make decisions? Do you may good or bad ones? Now, scientists have found that the precision with which people make decisions can actually be predicted by measuring their pupil size before they're presented with any information about the decision.

"We are constantly required to make decisions about the world we live in," said Peter Murphy, one of the researchers, in a news release. "Researchers have long known that the accuracy and reliability of such everyday decision making can be tremendously variable for different people at different times."

In order to investigate decision making a bit further, the researchers recruited 26 volunteers and measured their pupil sizes as they performed a visual choice-based task. This task was designed to mimic the kinds of perceptual decisions that are encountered in everyday life. In the end, they found that pupil size gave a good indication of how responsive a person was at any given moment.

"In this study, we show how precise and reliable a person is in making a straightforward decision about motion can be predicted by simply measuring their pupil size," said Murphy. "This finding suggests that the reliability with which an individual will make an upcoming decision is at least partly determined by pupil-linked 'arousal' or alertness, and furthermore, can potentially be deciphered on the fly."

In fact, the researchers found that a larger pupil size indicated a poorer upcoming task performance due to more variability in the decisions made once the relevant information was presented. In addition, certain individuals with the largest pupils overall tended to be the least consistent in their decisions.

"This new information could prove valuable for future research aimed at enhancing the precision of decision making in real time," said Murphy.

The findings are published in the journal Computational Biology.