Slow and Steady Does Not Always Win the Race: Investigating the Effect of Processing Speed across Five Naming Tests.

OBJECTIVE: This retrospective study investigated the effect of processing speed on confrontation naming performance via five naming tests with varying time components.

METHOD: The effect of processing speed, as measured by the Wechsler Adult Intelligence Scale-Fourth Edition Processing Speed Index (PSI), and cognitive impairment were examined using Boston Naming Test, Neuropsychological Assessment Battery Naming Test, Visual Naming Test (VNT), Auditory Naming Test (ANT), and Woodcock-Johnson III Rapid Picture Naming (RPN) performance among a mixed clinical sample of 115 outpatient veterans.

RESULTS: PSI scores accounted for 5%-26% of the total variance in naming test performances. Comparison of cognitively impaired versus unimpaired participants found significant differences and medium to large effect sizes (η(2) = .08-.20) for all naming measures except ANT tip-of-the-tongue responses. After controlling for the effect processing speed, VNT tip-of-the-tongue responses also became non-significant, whereas significant group differences remained present for all other naming test scores, albeit with notably smaller effects sizes (η(2) = .06-.10).

CONCLUSIONS: Confrontation naming test performance is related to cognitive processing speed, although the magnitude of this effect varies by the demands of each naming test (i.e., largest for RPN; smallest for VNT). Thus, results argue that processing speed is important to consider for accurate clinical interpretation of naming tests, especially in the context of cognitive impairment.