Diagnostic overshadowing and mental retardation: a meta-analysis.

Clinicians who minimize the significance of emotional disorders in persons with mental retardation may be displaying the diagnostic overshadowing judgmental bias. A meta-analysis of the existing literature on this bias was conducted to determine its reliability, the size of its effect, and its potential clinical significance. Results show the effect to be reliable across studies; the size of the effect was small to moderate. Interpretation of the clinical significance of these results is clouded by the absence of in vivo studies. Additional concerns include insufficient attention given to clinician and situational variables moderating the presence of diagnostic overshadowing.