Effects of retinal eccentricity on the lateralized processing of categorical and coordinate spatial relations.

Kosslyn's (1987) hypothesized cerebral hemispheric asymmetries for processing categorical and coordinate spatial relations were explored, using stimuli presented at varying degrees of retinal eccentricity. Thirty-three adult males performed hemifield reaction-time tasks requiring categorical or coordinate judgements. The hypothesized asymmetries were observed when stimuli were presented at 3 degrees of visual angle, but not at 1 or 9 degrees. Nevertheless, correlational analyses supported the existence of separate neural subsystems for categorical and coordinate processing. The results suggest that the model accurately predicts performance asymmetries only under specific conditions.