Louvain, Librairie Universitaire 1925 292pp., text in English, in the series "Etudes de psychologie publiées sous la direction de A. Michotte" volume II fasc.1, 25cm., original softcover, pages still uncut, very good, rare, [from the preface: "The experiments reported in this monograph were performed in the Laboratoire de psychologie expérimentale, at the University of Louvain, and this work was approved as a these d'agrégation to the Institut Supérieur de philosophie of that University"], P94339