Thirty-three patients in long-term individual therapy were referred to one of three weekend groups: two experimental (affect-arousing, gestalt therapy) groups and one control (meditation-Tai Chi) group. The impact of the weekend group experience (WGE) on individual therapy was examined six and 12 weeks later. At six weeks the patients in the experimental groups showed, on some measures, a significantly greater improvement in their individual therapy than did controls. By 12 weeks, there were no demonstrable differences. The WGE was not without risk: even though the group leaders were highly trained, responsible clinicians, two patients suffered considerable psychological damage. The control (meditation-Tai Chi) group offered a relatively innocuous experience; there was no risk, but few members found the specific procedures useful in their lives. Intense affect arousal in the WGE was not related to positive change in subsequent individual therapy. Those expressing the greatest affect in either experimental group were no more likely to have had a measurable positive impact on their subsequent individual therapy than patients expressing little or no measurable affect.
Yalom, I. D., Bond, G., Bloch, S., Zimmerman, E., & Friedman, L. (1977). The Impact of a Weekend Group Experience on Individual Therapy. Archives of General Psychiatry, 34(4), 399–415. https://doi.org/10.1001/archpsyc.1977.01770160033002