Early History of Reaction Time Research

Reaction time is measured in a variety of psychological experiments. The history of reaction time in the 1800s is discussed by Christopher D. Green in this mini-documentary.

What were some of the reasons for differing reaction time measurements among researchers? Could this occur today? How? Does the apparatus used by Wilhelm Wundt diminish his impact on the field of scientific psychology? Why or why not? What is a complication experiment?