A validity scale sign calling for caution in the interpretation of MMPIs among psychiatric inpatients

Three expert MMPI judges classified 100 psychiatric inpatients as psychotic or non-psychotic on the basis of their MMPIs. Validity scale data, as well as clinical scale scores, were included for 50 of the profiles, while the validity scale scores were withheld from the judges for the remaining 50 profiles. Within each of the above two groups, half had a "positive" validity scale sign (a defensive validity scale configuration defined as L or K greater than or equal to 70, or both greater than or equal to 60) and half had a negative validity scale sign, indicating a lack of defensiveness. Using actual diagnosis as the external criterion, results indicated that the majority of defensive psychotic patients produced clinical scale configurations which appeared nonpsychotic to the judges. Conversely, the majority of nondefensive nonpsychotics produced psychotic-appearing clinical scale configurations. These two types of test misses suggest that K corrections on MMPI scales relating to psychosis are not optimal for psychiatric inpatients. Guidelines were developed for interpreting defensive profiles.