People with larger pupil size bad decision makers

People with larger pupil size tend to be inconsistent in their decisions, says a study.

Once the relevant information was presented, a larger pupil size indicated poorer upcoming task performance owing to more variability in the decisions made.

Pupil size gives a good indication of how responsive a person is at any given moment, with larger pupils correlating with increased responsiveness.

When hyper-responsive, decision making appears to be less reliable and will more likely lead to undesirable outcomes, the findings showed.

"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," said co-researcher Peter Murphy from Leiden University in the Netherlands.

The results were obtained by measuring the pupil size size of 26 volunteers before each segment of a visual choice-based task began and monitoring each participant's subsequent performance in deciding which direction a cloud of dots was moving in.

These results were then combined with a simple mathematical model that described how people make decisions.

The results were obtained by measuring the pupil size of 26 volunteers as they performed a visual choice-based task designed to mimic the kinds of challenging perceptual decisions that are frequently encountered in everyday life.

Critically, the findings also open up areas for future research aimed at improving the precision with which we make decisions, to help us achieve better outcomes from the choices that we make.

The study appeared in the journal PLOS Computational Biology.