For more than a century, scientists have understood that three factors control pupil size: light, focus distance, and cognitive processes like emotions or mental effort. Now, researchers at Karolinska ...

Two heads are better than one, as the saying goes, and sometimes two instruments, ingeniously recombined, can accomplish feats that neither could have done on its own.

Forecast issued at 4:50 am EST on Thursday 20 February 2025.