The 'Reaction experiment with Hipp chronoscope' is one of the classical experiments of modern psychology. This paper investigates the technological contexts of this experiment. It argues that the development of time measurement and communication in other areas of science and technology (astronomy, the clock industry) were decisive for shaping the material culture of experimental in psychology. The chronoscope was constructed by Matthaus Hipp (1813-1893) in the late 1840s. In 1861, Adolphe Hirsch (1830-1901) introduced the chronoscope for measuring (...) the 'physiological time' of astronomical observers. Hirsch's observatory at Neuchatel (Switzerland) served to control the quality of clocks produced in the nearby Jura mountains. Hipp provided the observatory with a telegraphic system that sent time signals to the centers of clock production. Time telegraphy constituted the stable surroundings of the reaction time experiments carried out by both astronomers and psychologists. This technology permitted precise measurements of short time intervals and offered to Hirsch, as well as to Wilhelm Wundt (1832-1920), a useful metaphor for conceptualizing their respective 'epistemic objects'. But time telegraphy also limited the possibilities of the experimental work conducted within its framework. In particular, noise from outside and inside the research sites at Neuchatel, Leipzig and elsewhere disturbed the precise communication of time. (shrink)