Roy Wallis in his book _The Road to Total Freedom_ mentions a third study done by John Colbert, "An Evaluation of Dianetic Therapy", Thesis for the degree of Master of Science in Education, School of Education, The City College, New York, 1951.

This was a pilot study, and did not use a control group. His findings were that "fifteen individuals were believed to have undergone changes that tended in the negative direction, but these changes were in all but one case not unequivocally negative." Of the remainder of the sample of 24, six were believed to have undergone no change while the pattern of change in the remainder was in doubt. In short, Colbert felt the effect was either none or detrimental.