Two studies concerned effects of sex of Ss, sex of E, positive vs negative reinforcement (i.e., attention vs inattention), and time trends, on the conditioning and extinction of participation in structured and unstructured small group discussions. Previous results indicated reinforcement is effective only when administered by an E of the same sex as Ss. Present results did not support this expectation and also were not consistent with each other. Exp. I was partly consistent with expectation only when E was male; no conditioning was obtained by female Es. For Exp. II only the female E produced conditioning. Extinction effects in both experiments were inconsistent with expectation. In an earlier study (Cieutat, 1962) and in both Exps. I and II the same four factors were evaluated with some design modification, and were found to interact complexly and significantly ( p < .01, < .10, < .10, respectively). These interactions between sex of E, sex of Ss, reinforcement, and time, though significant in three independent evaluations, were so because of different trends in each case. These differences are discussed in terms of uncontrolled personality differences between Es and Ss.
