Measuring Change in Psychic Structure: The Scales of Psychological Capacities (SPC)

Since comparative psychotherapy research has advanced to evaluate long-term psychotherapy, there is an increasing demand to measure mode-specific effects. Structural change is one of the psychoanalytic concepts to grasp the effects beyond symptoms of psychoanalytic psychotherapies. The Scales of Psychological Capacities (SPC) are an attempt to measure this construct on an empirical basis. Inter-rater reliability and test-retest reliability (stability) of the instrument was prooven using a sample of depressed patients. The mean Intra Class Correlation Coefficient was 0.82, indicating good reliability. The mean stability coefficient (SPC total score=0.88) was very satisfying. Construct validity of the instrument was proven by discriminant and convergent validity with well established construct-near and construct-distant measures (validity study I). Additionally a known-groups approach was administered using different diagnostic groups (validity study II), and diagnostically specific constructs like impulse-/affect control and mood regulation. Both validity studies gave good evidence that the SPC measure beyond symptoms and are a valid measure of psychic structure. Sensitivity to change was investigated by means of a pre-post comparison of the effects of psychoanalytic long-term psychotherapy as an intervention supposed to bring about structural change, again using a sample of 42 patients with a depressive disorder. The data clearly revealed a very satisfactory sensitivity to change of the SPC for depressive patients, showing a mean effect-size of 1.84. This result was also clinically significant (using the reliable change index), when compared with 60 healthy controls. In summary, there is empirical evidence that the Scales of Psychological Capacities are a measure to grasp reliably and validly structural change as one construct underlying mode-specific effects of psychoanalytic psychotherapies and that they are a suitable instrument for psychoanalytic process-outcome research.

Key words

Scales of Psychological Capacities (SPC) - psychic structure - psychometric qualities