Eyeballing Behavior

Speed reading? How about speed COUNTING?

This is Sandra Tsing Loh with the Loh Down on Science.

Lights out! The pupils of your eye immediately widen to capture EVERY bit of light. But did you know your pupil size can still change even if the lighting remains consistent? Could it be changing based on HOW MANY objects you see?

Elisa Castaldi from the University of Pisa in Italy and team wondered. 

They had fifteen people look at either eighteen or twenty-four dots. Sometimes, the dots were connected by lines to form dumbbell shapes. This made it seem like there were HALF as many objects. Researchers then measured how much pupil size changed in response to the dots observed.

And? Twenty-four single dots produced almost TWICE the change in pupil size compared to eighteen connected dots. So, the pupil size DID get bigger with more perceived dots! 

In short, – more dots, bigger pupils! The researchers think this simple test could help identify math learning disabilities in very young children! 

My, what big eyes you have….the better to count with!

Reference: Castaldi, E., Pomè, A., Cicchini, G. M., Burr, D., & Binda, P. (2021). The pupil responds spontaneously to perceived numerosity. Nature Communications, 12(1). https://doi.org/10.1038/s41467-021-26261-4