Obtained his PhD degree in psychology after school and university experience in Germany, France and England. Having worked as a psychologist during the Second World War at the Mill Hill Emergency Hospital, he was appointed Professor of Psychology in the University of London, and Director of the Psychological Department at the Institute of Psychiatry (Maudsley and Bethlem Royal Hospitals). He lectured in many countries, and was Visiting Professor at the Universities of Pennsylvania and of California. Known mainly through his experimental researches in the field of personality, he wrote hundreds of articles in technical journals. He advocated the highest degree of scientific rigour in the design of psychological experiments and was very critical of much loose thinking current during his lifetime under the guise of 'psychology'.