My research is concerned with the study of social change, from the structural processes founding social influence (power, norms, interdependence, etc.) to the cognitive and motivational mechanisms that determine individual change. This work is intended to show that it is possible to introduce a change in all human activities and structures, and to show which are the specific processes -- in particular conflicts -- that underlie specific forms of change. This programme has been applied to five domains of human activity: perception, reasoning, motivation, learning, and attitudes.