Defence mechanisms were measured by using the TAT (thematic apperception task) The participants were shown the pictures and then must tell the story, which is then analysed. Each story was scored by a trained coder looking for three defence mechanisms.
Results: The results of the correlations were: denial 0.80, projection 0.85, and identification 0.78. It was found that the personality correlations were the same for both genders,
Conclusion: Diffused identity status gives the lowest self-esteem, moratorium gives fairly low self-esteem. The study helped to demonstrate what level each personality characteristic relates to the use of defence mechanisms.
A strength of the study was that care was taken to measure the concepts. The interpretation of the TAT stories was carried out by experienced coders. There was a high level of correlations between two sets of coding, thus the study has high reliability.
A further strength was that, the researchers were able to check that the Q-sort measured what it was meant to measure because they could look at factors that should go together.
On the other hand, a weakness of the study is that assumptions about the measures and their validity have to be made because defence mechanisms are unconscious processes, and are therefore not measurable.
Also, there were differences between people in the four categories; yet they were put into one of the four identity personality categories. Categorising people in this way means ignoring differences in data.
Therefore the conclusions may not be valid.