The hand-lateralization of spatial associations in working memory and long-term memory

Spatial-numerical and spatial-positional associations have been well documented in the domains of numerical cognition and working memory, respectively. However, such associations are typically calculated by directly comparing (e.g., subtracting) left- versus right-hand responses; it remains an open question whether such associations reside in each hand individually, or are exclusively localised in one of the two hands. We conducted six experiments to investigate the hand-lateralization of both spatial-numerical and spatial-positional associations. All experiments revealed that the spatial associations stemmed from left-hand responses, irrespective of the handedness of the subjects, but with the exception of the magnitude comparison task (Experiments 5 and 6). We propose that the hemispheric lateralization of the tasks in combination with the task-relevance of spatial associations can explain this pattern. More generally, we suggest that the contributions of left and right hands require more attention in spatial-numerical and spatial-positional research.