An evaluation of an MMPI response consistency measure.

Response inconsistency as an index for invalidating MMPI protocols was investigated by measuring the number of inconsistent responses given to 14 pairs of identical items by brain-damaged and nonbrain-damaged schizophrenic, alcoholic, neurotic and normal patients (n = 22 in each of the 8 groups). In addition the patient's number of inconsistent responses were correlated with the usual MMPI validity measures (?, L, F and K). Although all the response consistency scores of the groups were high it was found that the brain-damaged were more response inconsistent than the nonbrain-damaged patients (regardless of psychiatric diagnoses). The correlations between response inconsistency and the MMPI validity measures were significant but low. Because of the over-all high level of response consistency found for all the groups, it was concluded that MMPI protocol validity should be based on the validity scale measures, rather than upon response inconsistency.