The stability of tachistoscopic measures of hemispheric specialization

Two-week test-retest reliabilities were determined for two tachistoscopic tasks, consonant-vowel-consonant trigrams and dot location, in 48 right-handed university students. Both visual field and laterality scores were examined. Analysis of variance showed no significant main effects or interactions of session for either task, indicating stability of mean performance and laterality scores. Likewise, grouping subjects as "high" or "low" by median laterality scores showed concordance across sessions for both tasks. Test-retest correlations were moderately high for all verbal task measures and for visual field scores for the dot location test. However, laterality indices for dot location showed low stability despite comparable within-session reliabilities of laterality scores for the two tasks. These findings suggest stability of group means and subgroups for verbal and dot location tachistoscopic measures. However, the degree to which individual scores are predictable from one session to the next differs between the two tasks.