The effects of social desirability response bias on STAXI-2 profiles in a clinical forensic sample.

OBJECTIVES: This study investigated the proposition that the 'State-trait anger expression inventory' (2nd ed.; STAXI-2) is susceptible to impression management (IM) and Self-Deceptive Enhancement (SDE) in clinical forensic populations. It was hypothesized that individuals engaging in IM would report significantly lower levels of trait anger, external expression of anger, and internal expression of anger on the STAXI-2. Those reporting above average SDE were predicted to claim higher levels of anger control.
DESIGN: A between-groups design was used, comparing STAXI-2 scores of individuals who reported high levels of IM and SDE to those who did not.
METHOD: One-hundred and fifty-nine male patients of a community forensic mental health service, referred for assessment of stalking behaviours, completed the STAXI-2 and Paulhus Deception Scales (PDS). Individuals engaging in high levels of IM and SDE were compared to low scorers in regard to STAXI-2 scales using Mann-Whitney U tests.
RESULTS: Individuals engaging in IM had significantly lower levels of reported trait anger, outward expression of anger, and inward expression of anger, and higher levels of anger control. Similar results were found with the SDE scale, although the magnitude of the effect was smaller and not apparent on all subscales.
CONCLUSIONS: The STAXI-2 was vulnerable to social desirability response bias in this sample of forensic clients. Where the STAXI-2 is used as a basis for treatment recommendations and decisions, it should be administered and interpreted in conjunction with a recognized measure of such bias to improve validity.