The aim in this study was to develop and validate a set of scales to measure subject motivation and behaviour in psychological experiments. This was achieved by factor analysing the responses by 140 subjects to 60 statements concerning the feelings aroused and the behaviour adopted when a subject in a psychological experiment, and attitudes towards psychology, psychological research, science, and scientific method. Seven factors were obtained: I Attitudes towards psychology and psychological research II Evaluation apprehension III The good-negativistic subject role IV Volunteering V The faithful subject role VI Awareness of deception and VII Attitudes towards science and scientific method. The validity of each factor was studied by considering its relationship with other psychological variables and the other factors, using a sample of 96 psychology students. Reliability estimates were also obtained from test-retest scores for 31 subjects, as well as from item-total correlations. The limitations and usefulness of the scale are discussed, and suggestions for further research are made.