1873 doctoral dissertation at the University of Bonn; 1873-1880 studies and work as tutor at several universities in England and France; 1880-86 lecturer at the University of Berlin; 1886-94 ausserordentlicher Professor at Berlin; 1890 co-founder and editor of the Zeitschrift für Psychologie und Physiologie der Sinnesorgane; 1894-1909 professor at the University of Breslau; established laboratories at the Universities of Berlin and Breslau and also taught at Halle.