German psychologist and philosopher regarded as the guiding force behind the experimental study of thought processes identified with the Würzburg school of psychology.

Külpe's early academic interests vacillated between history and psychology. After completing a dissertation on feeling for Wilhelm Wundt (Wundt, Wilhelm), the founder of experimental psychology, at the University of Leipzig (1887), Külpe spent eight years at the Leipzig laboratory. During most of that time he acted as Wundt's assistant. In 1888 Külpe became Privatdozent (lecturer) at the university. He wrote Grundriss der Psychologie (1893; Outlines of Psychology), in which he defined psychology as a science concerned with experiences dependent on the experiencing individual and outlined the findings of experimental psychology.

In 1894 Külpe was appointed professor at the University of Würzburg, and under his inspiration and direction the institute published some 50 experimental studies before his departure for the University of Bonn in 1909. Best known is his research on the effects of attitudes and tasks on perception and the course of recall and thought.

In 1913 Külpe took a post at the University of Munich. At the time of his death he was writing another systematic treatment of experimental psychology. Die Realisierung, 3 vol. (1912–23; “Realization”), considered to be a valuable contribution to the theory of knowledge, was his last published work.