Performance of normal adults on the Luria-Nebraska Neuropsychological Battery, form I.

To examine three problems in the interpretation of the Luria-Nebraska Neuropsychological Battery (LNNB), the normal participants from four different studies were pooled to form a sample of 241 LNNB profiles. The first problem addressed was the LNNB's false positive rate. All five yes/no decision rules were applied simultaneously. Each individual rule had a 0% to 8% false positive rate: combining the rules in four different ways increased the false positive rate by 0% to 6%. When divided into over and under 65 years old groups, each rule applied to the younger group had a 0% to 5% false positive rate: combining them increased the rate to 6-8%. When applying the rules to the older group, each rule had a 0 to 27% false positive rate: combining all rules but the one with the highest error rate produced a false positive rate of 27%. The false positive rate for the entire sample was 12%. To solve the second problem of interpretation, making qualitative item analyses easier, the difficulty level (i.e., percentage of normals missing the item) for each item was calculated. The third problem was the LNNB's malingering formula's accuracy. The formula was applied to the sample: as expected, the normal profiles had an inaccuracy rate of 26%. The few mildly impaired profiles had a 6% inaccuracy rate. When applied to the entire sample of normals and using the appropriate interpretive guidelines, the formula had a false positive rate of 1%.