[The development of psychophysiological measurement,1850-1865].

Toward the end of the 1840s, Hermann von Helmholtz (1821-1894) began to investigate experimentally the propagation of stimuli within nerves. Helmholtz's experiments on animals and human subjects opened a research field that in the following decades was intensively explored by neurophysiologists and experimental psychologists. Studying the concrete experiemental settings and their local contexts shows how deeply the work of Helmholtz, Adolphe hirsch (1830-1901), Franciscus Donders (1818-1889) and others was embedded in the history of culture and technology. In particular, the rapidly growing technologies of electromagnetism, which gave rise to telegraphy and electric clocks, facilitated the time measurements of 19th-century physiologists and psychologists. However, the transition from frogs to human beings as model organisms confronted the time-measuring psychophysiologists with a whole range of experimental parameters that were difficult to control (temperature, attention etc.). It is no wonder then that it took some 20 years before this branch of research stabilised.