In right handed people, which hand is better at mirror writing? Are there any differences between unimanual and bimanual conditions?
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Mirror writing is a phenomenon which can be deliberate, spontaneous, or involuntary. It has been anecdotally reported that mirror writing is easiest when simultaneously writing forwards with the dominant hand. A study carried out by McIntosh and Della Sala on a mirror writing artist named KB, found that their results concurred with this, and that mirror motor movements were being used when KB mirror writes with the left hand while simultaneously writing forwards with the right, in a motor congruent condition. KB’s unimanual left hand mirror writing was also the most similar script, in terms of writing style, to his normal right hand forwards writing. The present study was conducted to investigate whether these same homologous mirror movements are used by naïve participants when they are asked to mirror write. The results concurred with the anecdotal claims, and the left hand mirror writing had fewer letter reversal errors when the right hand was also writing forwards, than any other mirror writing sample, under any condition. However the writing style of participants mirror writing was not statistically similar to their right hand forwards script under any conditions. This suggests that although a skilled mirror writer such as KB can mirror write by using the same learned motor movements of the right hand to write backwards with the left, that normal people are more likely solving the mirror writing task perceptually, drawing on a picture of how the word should look.