FORM-SPECIFIC PRIMING AND FUNCTIONAL BRAIN ASYMMETRIES IN PERCEPTUAL IDENTIFICATION

Word form representations in intact cerebral hemispheres were studied by a lateralized perceptual identification priming task. During the st udy phase, word forms were primed by displaying words visually in uppe rcase or lowercase letters. During the test phase, perceptual identifi cation of non-studied baseline words and studied words (presented in s ame or different lettercase as studied) was tested by displaying targe ts in the left or right visual field. Experiment 1 showed that the hem ispheric pattern of priming effects was dependent on the lettercase at test. For uppercase test items, only the left visual field/right hemi sphere was sentitive to study-test changes in lettercase, replicating an earlier result obtained in word-stem completion (Marsolek, Kosdyn a nd Squire, 1992). However, lowercase test items did not reveal any asy mmetries in the form-dependent priming component indicating that in so me conditions form-specific representations are computed in the left h emisphere also. No asymmetries were found in the abstract, form-indepe ndent component of priming. Experiment 2 revealed that use of explicit memory in the perceptual identification task eliminated the form-spec ific priming effects and suggested that the results of Experiment 1 we re uncontaminated by explicit memory.