A tale of two constructs: confirmatory factor analysis of performance and symptom validity tests.

Background: Performance validity (PV) and symptom validity (SV) tests assess biased responding that impact scores on neuropsychological tests. The extent to which PV and SV represent overlapping or unique constructs remains incompletely defined, especially among psychiatric patients in a non-forensic setting. The current study investigated this question using confirmatory factor analysis.

Method: Eighty-two inpatients with mood disorders were administered the Word Memory Test, and its primary indices formed a latent variable of PV. From the Minnesota Multiphasic Personality Inventory-2 the Fake Bad Scale (FBS), Response Bias Scale (RBS), and Henry-Heilbronner Index (HHI) were employed as a latent SV variable. Two models of the relationship between PV and SV were compared. One freely estimated the shared variance between SV and PV latent constructs. The other assumed the relationship between SV and PV was homogeneous, and covariance was fixed to 1.0.

Results: In the freely estimated model, covariance between PV and SV was -0.18, and model fit was excellent (CFI = 0.098; TLI = 0.096; SRMR = 0.08). For the fixed model, the RBS, HHI, and FBS achieved low loadings on the SV construct, and model fit was poor (CFI = 0.66; TLI = 0.43; SRMR = 0.42).

Conclusions: PV as indexed by the WMT and SV measured by the MMPI-2 are not overlapping constructs among inpatients with mood disorders. These data imply that PV and SV represent distinct constructs in this population. Implications for practice are discussed.