With reference to W. R. Bion's theory about individual's reactions to group stimuli the main hypothesis was formulated thus: individual's Valency (V) and Productivity (W) undergo changes in certain (definable) directions under the influence of longterm group psychotherapy. The main hypothesis was refined into seven sub-hypotheses. These were measured by four projective tests: Reaction Group Situation Test (RGST), Self Perceptual Q-sort (SPQ), Q-SORT(overt) and Q-SORT(covert). 48.0% of the total number of modalities, 120 out of 252, developed in a predicted and eligible direction. 29.0%, 74 modalities out of 252, remained unchanged whereas 23.0%, 58 modalities out of 252, developed in an opposite to predicted and non-eligible direction. Group members' Productivity (W) developed most of all the modalities in a predicted (eligible) direction. Group members' Valency and Productivity pattern (VP) changed least of all the modalities. The group members Valency (V) for the basic assumption Dependency (baD) developed most of all the modalities in an opposite to predicted, i.e. non-eligible direction.