Hold a pen at arm's length, focus on it for five seconds, then look at an object approximately 10 feet away for another five ...

Article Google Scholar Jude EB, Ryan B, O'Leary BM, Gison JM, Dodson PM . Pupillary dilation and driving in diabetic patients. Diabetic Med 1988;15:143–7. Article Google Scholar Watts P ...

Dilation and constriction of the pupils reflect not only changes in light intensity but also ongoing mental activity. The response is a measure of interest, emotion, thought processes and attitudes ...

For example, using alcohol, marijuana, or cocaine can cause dilated pupils, and opiates can cause pupillary constriction or dilation. These effects are usually symmetrical, but they may be unequal.

It directly contradicts the old belief that pupils are largest during inhalation and smallest during exhalation. According to the researchers, the processes of dilation and constriction overlap ...