Lateral preference patterns as possible correlates of successfully switched left hand writing: data and a theory.
Left-handers often have had to contend with pressure to switch their preferred writing hand and shift attempt reports are common, especially among older adult left-handers. Three groups of left-handers can be defined by combining two variables, writing hand side and the report of a rightward hand preference shift attempt. The three groups are, first, right hand writers who report a rightward shift (successfully shifted left-handers); second, left hand writers who report a rightward shift attempt (unsuccessfully shifted left-handers); and, finally, left hand writers who do not report a rightward shift attempt. The underlying mechanisms that determine the success or failure of a handwriting shift attempt remain unclear. The present study examined the history of attempts to switch the preferred writing hand in a sample of 1277 adults aged 65 to 100 years of age. Older adults are well suited to participate in such a study because pressure to switch hand preference was especially severe for those who grew up in the early part of the 20th century; reports of rightward shift attempts are more common in this age group than among younger adults. Our results suggest that the three groups of left-handers, distinguished by the presence or absence of a shift history report and writing hand side, can also be distinguished from each other on the basis of their overall lateral preference profiles (the sides of hand, foot, eye, and ear preferences). Left hand writers, with and without reports of a rightward shift history, showed stronger left side lateralisation patterns when compared to right hand writers who reported a rightward switch (the successfully shifted left-handers).