The impact of individual characteristics on the attitudes and performance of students in a college psychology course using the guided design approach was examined. With this teaching method students work in groups to solve problems, gaining experience in the cognitive processes of concept reorganization, symbolic translation, data interpretation, and prognostication and in presenting and defending their ideas. Subjects consisted of 44 male and 41 female students enrolled in a general psychology course. Scores on the intuitive, feeling, sensing, and thinking dimensions of the Myers-Brigg Type Indicator, Form G, were used to divide students into three groups: sensing/thinking types, intuitive/feeling types, and mixed group. After completing the guided design project, students answered questionnaires. A group proficiency score was generated by comparing the groups' decisions with a preferred decision or ranking. Results include the following. The homogeneous groups performed better than the mixed group. The sensing/thinking types responded most favorably to guided-design activities. Only the sensing/thinking group tended to want to spend more time in guided-design activities. (RM)