Key points are not available for this paper at this time.
*Department of Psychology, University College London, Gower Street, London WC1E 6BT, U.K. **United Medical and Dental Schools of Guy's and St. Thomas' Hospitals, St. Thomas' Hospital, London SEI 7EH U.K. Submitted August 1, 1985; accepted August 23, 1985.
Vincent et al. (Wed,) studied this question.