Unresolved questions concerning the effectiveness of psychological assessment as a therapeutic intervention: comment on Poston and Hanson (2010).

In a recent article in this journal, Poston and Hanson (2010) reported a meta-analysis of 17 studies on the use of psychological assessment as a therapeutic intervention (PATI) and concluded that "psychological assessment procedures-when combined with personalized, collaborative, and highly involving test feedback-have positive, clinically meaningful effects on treatment" (Poston & Hanson, 2010, p. 203). Although extant data suggest that PATI can sometimes exert positive effects, Poston and Hanson's (2010) meta-analysis may overstate the magnitude of these effects because the authors (a) included several studies that combined assessment with treatment components that are irrelevant to PATI, sometimes rendering it impossible to attribute any observed effects to PATI per se and (b) excluded numerous nonsignificant results. Moreover, the studies Poston and Hanson (2010) reviewed neglected to rule out Barnum effects as alternative explanations for client improvement, raising the possibility that PATI works for reasons other than those proposed by its advocates. We conclude that Poston and Hanson's (2010) review leaves a number of lingering questions concerning the treatment utility of PATI unanswered.