Abstracts

Rationale: Practice effects are a concern in cognitive assessments of patients with epilepsy, who frequently must undergo repeated testing to evaluate changes related to the disease or to inteventions. However, practice effects occurring between two similar tests administered during a same testing session have received little attention. We explored effects occurring between two naming tests (the Boston and Auditory Naming tests), and between two tasks that used the same unfamiliar faces but assessed different functions (learning vs. discrimination). We also modified the Victoria Stroop test by exchanging the condition of naming the ink color of non-color words for a condition in which color-name words that are written in colored ink must be read, and we compared performance on the modified (MNI) version to the original. We predicted between-test practice effects for the two naming tests and for the two face tasks, and we expected reduced within-test practice effects in the modified Stroop compared to the original.Methods: 41 healthy volunteers were assigned at random into one of two groups such that the groups were matched on gender, age and years of education. The two groups performed the two naming and two face tests in an opposite order from one another. One group was given the Victoria Stroop, and the other group the MNI Stroop.Results: Prior experience with one naming test did not influence performance on the other. However, prior experience with the face discrimination test led to significantly better scores on the first trial of the face learning test, and prior experience with the face learning test resulted in significantly faster performance of the face discrimination test. Finally, significantly more subjects made errors on the interference condition of the MNI Stroop than on the original Victoria Stroop.Conclusions: Practice effects were not observed on the naming tasks. This finding supports the notion that the Boston Naming Test and the Auditory Naming Test assess different functions and is consistent with reports that performance on the two tests is disrupted differentially by anterior vs. posterior resections from the left temporal lobe. Prior experience with each face task did improve performance on the other. It is not surprising that the learning task should facilitate the discrimination task, but it is interesting that the reverse was also true; the finding demonstrates that experience with specific stimuli can influence a learning task even when the stimuli are seen in a different context. Finally, the Stroop results confirm that naming the ink color of non-color words in the Victoria Stroop does provide practice that reduces the desired effect in the final interference condition; thus the revised task should provide a more sensitive measure of susceptibility to interference. Taken together, these findings show that within-session practice effects can occur with some stimuli, and interpretation of clinical results from patients should be made with this knowledge in mind. Supported by Canadian Institutes of Health Research