Yerkes

Yerkes is a surname of English-language origin. Notable individuals include Robert M. Yerkes, an American psychologist who helped pioneer standardized testing for the U.S. military and is associated with the Yerkes–Dodson law, which describes how arousal affects performance; and Charles Tyson Yerkes, a Chicago financier whose philanthropy funded scientific research, most notably the construction of Yerkes Observatory.

Yerkes Observatory is an astronomical research facility in Williams Bay, Wisconsin. It was established in 1897 with a gift from Charles Tyson Yerkes and named in his honor. The observatory housed one of the largest refracting telescopes in the world at the time—a 40-inch (1.02 m) refractor built by Alvan Clark & Sons—along with other instruments used for stellar spectroscopy, variable star work, and related studies. For much of the 20th century it served as a major center for astronomical research and graduate training and remains a site of historical significance and preservation efforts.

The Yerkes–Dodson law, named after Robert M. Yerkes and John D. Dodson, states that performance increases with physiological or mental arousal but only up to a point; when arousal becomes too high, performance declines. The law is commonly cited to describe optimal levels of stress or alertness for tasks of varying difficulty.