Mirror writing in typically developing children: A first longitudinal study

•At age 4 years, children rarely produce reversals when copying digits and letters.•At age 5, the same children frequently reverse dictated left-oriented characters.•An implicit right-writing rule explains this reversal of single characters.•The rule depends on the direction in which the child writes (usually left–right).•Complete mirror writing of names seems to begin as soon as writing begins.

The present study examined the development of mirror writing in typically developing children using a longitudinal design involving 166 children initially aged 4–5 years. The children were tested three times, with approximately one year between tests. The main predictions were that: (i) mirror copying of characters at T1 (4- to 5-years old) will be less frequent than mirror writing from memory at T2 (5- to 6-years old), (ii) an implicit right-writing rule—which holds that children orient single characters toward the right and hence most frequently reverse the left-oriented characters (e.g., 3, J)—explains well both character reversal at T2 and T3 and changes between T2 and T3 (6- to 7-years old), and (iii) name-mirror writing is possible as soon as children start learning to write.