Handedness is related to memory via hemispheric interaction: evidence from paired associate recall and source memory tasks

Strongly right (SR)-handedness is associated with poorer memory performance than nonstrongly right (nSR)-handedness (e.g., Propper, Christman, & Phaneuf, 2005). The hemispheric interaction theory states that the nSR memory advantage occurs because nSR handedness, compared with SR, is a behavioral marker for greater interaction of the cerebral hemispheres. The hemispheric interaction theory predicts that the nSR advantage should be observed exclusively on memory tasks that require hemispheric interaction. The authors tested that prediction by comparing middle-aged and older adults on two memory tasks thought to depend on hemispheric interaction (paired associate recall, source memory) and two thought not to (face recognition, forward digit span). An nSR advantage was more robust for middle-aged than older subjects and, consistent with the hemispheric interaction theory, was found only on the tasks that depend on hemispheric interaction.