The achievement of informed consent from patients and potential research participants is considered a basic requirement in clinical care and clinical research, but ethicists have paid little attention to the psychological processes and social factors involved in sharing information between individuals. Although many studies on consent have provided useful results, they are rarely informed by basic research in the social sciences. As a result, there are a large number of methodological and conceptual issues which have not been adequately addressed. The purpose of this paper is to illustrate how the work of cognitive and social psychologists can provide insights that are both relevant and valuable to the process of attaining consent. Research in these areas within psychology has indicated that there are important individual differences in how much information people require and that patients' current state of mind can affect estimates of probability, thus making analogue studies misleading. Collaboration between psychologists and ethicists would be of great value in identifying likely areas of mutual interest, particularly the choice of language in consent forms and information sheets, the design of consent forms, the amount of information provided, and the specification of risks and benefits. Copyright (C) 1996 Elsevier Science Ltd