William R. Harrison

MMPI Overreporting by Vietnam combat veterans

The MMPI-PTSD scale is the only psychometric measure that has been cross-validated on Vietnam veterans for the determination of PTSD. Despite this, there may be problems with this scale related to symptom exaggeration. Three groups of Vietnam inpatients (N = 75) were defined carefully by both clinical and actuarial methods--PTSD combat, Non-PTSD combat, and Non-combat. This study applied symptom exaggeration methods based on the MMPI obvious/subtle items and on the F scale to these groups. Results show that all the items of this scale are either obvious or neutral, that a carefully distinguished PTSD group differentially responds to these obvious and neutral items relative to other inpatient Vietnam groups, and that the F scale is exaggerated by the PTSD group. In addition, a separate analysis on an independent sample of 50 combat and 50 non-combat Vietnam veterans showed that the combat group endorsed the obvious items on selected scales by 20 T score points at higher rates than other groups. Caution in the use of the MMPI-PTSD scale is discussed.

MMPI F-K index among hospitalized Vietnam veterans.

The F-K index of the MMPI has been used as a marker of symptom overreporting. One population for which previous research has shown this pattern is Vietnam in-country veterans with PTSD. This study assessed the F-K index on 515 inpatients: 329 Vietnam in-country and 186 Vietnam-era patients. Normative data on psychiatric inpatients were presented. Also, a special MMPI subscale (MMPI-PTSD), a measure to identify PTSD among these veterans, was used. Results showed that all Vietnam veterans, especially in-country veterans, overreport symptoms to a high degree. The overall mean for in-country vets was 7.3. Also, when the special MMPI-PTSD subscale was used, a vast majority of in-country veterans who were in the PTSD range had high F-K index scores. Dissimulation as a symptom of PTSD was discussed.

Congruity of rotational and pharmacological taste aversion (TA) conditioning within strains of selectively bred TA prone and TA resistant rats

Abstract Rotationally induced (motion sickness) taste aversions (TAs) were studied within strains of rats that had been selectively bred as efficient or inefficient learners of cyclophosphamide induced TAs to a saccharin solution. As hypothesized, rotation following saccharin ingestion produced reliable TAs within the TA prone strain, but had no comparable effect on TA resistant rats. Pseudo-conditioning- and restraint-control procedures supported a conditioning (associative) based interpretation of strain differences in TA acquisition. These results confirm that strain differences in TA conditionability are not restricted to the cyclophosphamide-induced TAs that were the selection bases of strain development. The rotational stimulation was delivered via a multisubject rotational apparatus that fulfills the design objectives of providing an efficient and inexpensive nonpharmacological approach to TA conditioning.

A multisubject rotational stimulator for taste-aversion induction

A new multisubject rotational apparatus for the induction of motion-sickness-induced taste aversions (TAs) in rats is described. This easily constructed device rotates up to 4 subjects that are individually restrained in plastic cylinders to minimize locomotion while providing consistency of rotational stimulation. The multisubject rotational apparatus, which fulfills the design objective of providing an inexpensive and efficient nonpharmacological approach to TA conditioning, can be modified for use with a variety of small animals and may also be applicable to other areas of motion-sickness research.

MMPI Scales and Subscales: Patterns of Older, Middle-Aged, and Younger Inpatients.

There has been virtually no research on the relationship of age and MMPI subscales, such as the Harris and Lingoes, Wiggins, Subtle/Obvious, and other specialized subscales. One hundred younger (less than or equal to 39), middle-aged (40-49), and older (greater than or equal to 50) psychiatric inpatients were compared on the basic 13 MMPI scales and 77 MMPI subscales. Results showed that, as a whole, older patients tended to respond more conservatively to these scales, to show less pathology, and to endorse fewer subtle/obvious items than the other age groups. They responded, however, lower on Dominance, on Hostility, and on Social Maladjustment. Later-life patients also endorsed differentially many of the Harris and Lingoes 4 and 6 subscales in the less pathological direction than did the other groups.

Interest patterns among Vietnam-era veterans.

The relationship between interest themes and posttraumatic stress disorder (PTSD) and its symptoms is virtually unknown. This study addressed three issues: (a) the relationship of interest themes to PTSD symptoms, (b) comparison of PTSD versus nonPTSD veterans on interest themes, and (c) a determination of those psychiatric symptoms and interest themes that differentiated PTSD from nonPTSD veterans. Vietnam-era veterans represented PTSD (n = 40) and nonPTSD (n = 35) groups. These subjects were administered a battery of psychological tests including the Strong-Campbell Interest Inventory and the MMPI (Scales 2, 4, 7, 8, and MMPI-PTSD Scale were used). Demographic/background variables were also obtained. Analysis shows no significant relations between PTSD symptoms and interest themes, no differences between groups on interest themes and, relative to psychiatric problems, occupational themes contribute in only a minor way to a PTSD/nonPTSD distinction. Discussion focused on the lowered interest patterns for these veterans and their generalized psychiatric problems.