FACTOR-ANALYSIS AND THE CEREBRAL HEMISPHERES - UNLOCALIZED FUNCTIONS

Previous factor analyses have employed lateralized task tapping proces ses (functions) whose localizations are thought to be known at the lev el of the cerebral lobe or finer. Here nine tasks are introduced to fa ctor analysis whose underlying processes have unknown localization. A new function identified as auditory emotional is found to be independe nt of asymmetry in a visual emotion judgment task, suggesting that lat eralized emotion judgments depend on modality specific processes. A se cond new function identified as visual temporal is found to be indepen dent of asymmetries in visual language recognition, posing constraints on theories that link lateralized language processes to processes dea ling with temporal sequencing. Another important finding is that the r ecognition of dichotic syllables relies on a previously identified pro cess, indicating that the process is better labelled auditory linguist ic than auditory lexical and suggesting that lexical status may be irr elevant to auditory language asymmetries. Also, a word naming task is found to produce visual field asymmetry because of a stimulus encoding (visual lexical) process, with no clear evidence found of influence f rom asymmetric response processes. Taken together, the full set of lat eralized processes appear to show high degrees of modality specificity and mutual independence (modularity). Copyright (C) 1996 Elsevier Sci ence Ltd.