Effects of blurring and stimulus size on the lateralized processing of nonverbal stimuli.

Right-handed subjects indicated whether two novel, nonlinguistic stimuli were physically identical or not. In Experiment 1 blurring these stimuli impaired performance when stimuli were projected to the right visual field but not when stimuli were projected to the left visual field. This lateralized effect of blurring is similar to earlier findings in letter-matching experiments and indicates that such effects do not depend on hemispheric differences in verbal mediation. Experiment 2 examined the lateralized effects of stimulus size using the same task as Experiment 1. The pattern of results from this experiment suggests that both visual spatial frequency and stimulus perceptibility contribute to interactions of stimulus clarity and visual field and that neither factor by itself may be the sole determinant of the lateralized effects of input variables.