He was trained in medicine at Heidelberg and became a physiologist, but he soon began collecting data on behavior as well as on structure. In 1873 he published his Principles on Physiological Psychology. This book of 870 pages eventually became three volumes totaling 2,317 pages in the sixth edition of 1908–1911. These six editions were, in effect, the history of experimental psychology's first 40 years. From 1875 until 1910, Wundt taught at Leipzig. There he established the world's first psychology laboratory (1875) and founded its first journal of psychology (1881). Wundt's laboratory research concentrated on two topics:(1) sensation and perception and (2) the measurement of reaction times. To study these, he used the technique of introspection, in which human subjects reported exactly what they experienced upon being presented with a stimulus (e.g., light). Despite the primitive conditions of this early laboratory remarkably little that Wundt did has been totally rejected, and the research he conducted created the basic character of modern experimental psychology.