A New-Dominant Hand: Can Forensic Document Examiners Correctly Associate the Dominant-Hand Writing to the Non-Dominant-Hand Writing of the Same Person?

Use of the non-dominant hand is a method sometimes employed by those trying to disguise their natural handwriting. However, intentional disguise is not the only reason a person may use his or her nondominant hand to write. The number of service members and civilians who have lost the use of their dominant hand due to injury and/or illness has risen steadily over the years. For those people, writing with their non-dominant hand is not done as a means of disguise but, rather, as a necessity. What was once their non-dominant hand must now become their new-dominant hand. As their population increases, forensic document examiners (FDEs) are more likely to be faced with a situation in which they must examine and compare writing from a person’s dominant hand to the writing from that same person’s non-dominant, or new-dominant, hand. In this study, fifteen FDEs performed comparisons between dominant-hand writing and non-dominant-hand writing of both printed and cursive samples. The FDEs were able to identify the dominant and non-dominant-hand writing of the same person with 93.75% accuracy for cursive writing (6.25% error rate) and 87.22% accuracy for handprinting (12.78% error rate). Nine laypeople (LP) performed the same examinations with much lower accuracy rates. Laypeople scored 81.02% accuracy for cursive writing comparisons (18.98% error rate) and 74.07% accuracy for handprinting comparisons (25.93% error rate). This study not only shows that FDEs can identify the non-dominant-hand writing of a person given only that person’s dominant-hand writing, but also that they do so with more accuracy than do laypeople.