Hemispheric Semantics: Effects of Pictorial Organization on Patients with Unilateral Brain Damage

Abstract

Memory for incongruous scenes (violating “knowledge-of-the-world”) versus unorganized (jumbled) arrays was tested in war veterans with unilateral penetrating missile wounds of the brain in order to assess hemispheric differences in semantic schemas in long-term memory. Left brain-damaged (LBD) patients were selectively impaired in remembering unorganized scenes compared to right brain-damaged (RBD) patients. There was no significant LBD-RBD difference in remembering incongruous scenes. The results confirm the presence of hemispheric asymmetry for semantic schemas in long-term memory, even in pictorial material. However, some features in the organization of semantic schemas are common to both hemispheres and suggests presence of similar knowledge systems. The asymmetry is discussed in terms of intact left hemisphere specialization for assigning meaning to a visual scene when obvious meaning appears to be absent.

Key Words:

• left hemisphere
• right hemisphere
• hemispheric asymmetry
• implicit knowledge
• semantic memory
• hemispheric memory