Abstract

The magnitude of Stroop interference has been used as an indicator of the efficiency of the inhibitory process (Dempster, 1992), an aspect of frontal lobe functions. Comalli, Wapner, & Werner (1963) found that the amount of interference begins to increase in the 65- to 80-year-old group in healthy adults. This study was conducted to examine the efficiencies of four interference indexes of Stroop test, such as Interference score, Interference ratio, CW correct response, and CW correct rate. First, the Korean-Stroop Neuropsychological Screening Test (K-CWST) was administered to 393 healthy older adults (age range: 50-83, mean age=66.57&#x00B1;6.20). After controlling the effect of education using ANCOVA, significant age effects were found in Interference score, Interference ratio, and CW correct response, not in CW correct rate. Second, 96 dementia patients and 132 healthy elderly whose age and education level were matched to the dementia patients were given the K-CWST. There were significant differences in all four indexes between two groups. Discriminant analysis, however, showed that CW correct response is the most efficient index to classify dementia patients and normals. The severity of dementia was the most highly correlated with CW correct rate (r=-.49, p<.001). These results suggest that although all four indexes are efficient measures of the inhibitory process, the best index for a specific study should be chosen according to the purpose of the study.