During hypnotic trance, it is easy to drive subjects to hallucinations with concrete form and features, and to give orders to be carried out both during and after trance. A possible hallucinatory order is age regression to a previous period of life. The aim of this study was to investigate through a Rorschach test and a test of intelligence the range of mental abilities both in basal conditions and in hypnosis with age regression. The purpose was to ascertain whether age regression is a real phenomenon, and to what extent it is able to modify the perception of reality. The study was conducted on 10 highly hypnotizable volunteers. Each participant was tested three times, in three different sessions (in basal conditions, in hypnotic regression of age, and in neutral hypnosis), in the frame of a Latin-square protocol. Heart rate, systolic, diastolic, and mean blood pressure, cardiac index, and total peripheral resistance were constantly monitored. The test of intelligence used was that of the progressive matrices of Raven. As evidence of age regression, each patient underwent a test of Rorschach in order to reveal features of infantilism associated with regression. The test of Rorschach carried out during age regression showed in all subjects a sharp increase in those variables that are typical of an infantile approach and a drop in those that are typical of an adult approach. This result confirmed the experimental hypothesis that patients were regressed to infantile age. The Raven matrices revealed a decrease in efficiency during hypnotic age regression in comparison to standard conditions (anagraphic age). The results demonstrated that age regression is real and measurable, and that in age regression conditions--but not in neutral hypnosis--subjects show a modified behaviour revealing a lower level of maturity. [ABSTRACT FROM AUTHOR]