> It was previously known that some people can change their pupil size at will, but by using indirect methods. > For example, researchers already knew that jus

> It was previously known that some people can change their pupil size at will, but by using indirect methods. > For example, researchers already knew that just thinking about the sun could constrict the pupils and that thinking of a dark room or mentally calculating something could dilate them, […] Apparently, it is about changing the pupil’s size without any physical or mental stimulus.