Proceedings of the Annual Meeting of the Cognitive Science Society

Increased left-handedness and atypical lateralization in individuals with neurodevelopmental and psychiatric disorders point to a deep yet unresolved connection between handedness, hemispheric asymmetry, and normal brain functioning. Most handedness-lateralization research has either excluded left-handers due to their higher variability, or failed to control the degree of handedness. The discrete categorization based on arbitrary criteria or cut-offs has made it challenging to address inter-individual variations in the lateralization of cognitive functions. In this study, capturing responses from across the handedness continuum in tasks of the divided visual half-field paradigm, we explored the lateralization patterns in different stages of visual processing of orientation, global-and-local, faces and words. We found that the degree of handedness significantly affects lateralization in all tasks except orientation. Notably, even though the direction of hemispheric preference did reverse in left-handers for visuospatial attention like in global-local processing, the same was not for word and face processing. Our results substantially evidence that handedness differentially influences the lateralization of visual processes. The observed relationship between the dominant hand and global-local processing significantly points to the action-dependent modulation of visual attention. We conclude that the degree of left-handedness is potentially a critical factor in lateralization, and a continuum approach would be beneficial to control for the individual variations in laterality research.