A recent poll on a Facebook page about left-handedness asked people to choose a picture that  best describes their left-handed position while writing. In reality, there are 4 different writing postures…straight and inverted left-handed writing and straight and inverted right-handed writing. These 4 postures are illustrated below. A large number of left-handers weighed in on this poll choosing either the first or second picture as representing their writing behavior.

A popular theory of the 1970’s claimed that writing hand posture revealed the hemispheric location of the speech center in the brain. Writers with straight posture have speech located in the hemisphere opposite to the writing hand…left-handers in the right hemisphere and right-handers in the left hemisphere. Writers with an inverted posture have a speech center in the hemisphere on the same side as the writing hand…left-handers in the left hemisphere and right-handers in the right hemisphere. Unfortunately, more direct study of the relationship between the writing hand and the location of the brain’s speech center did not support the theory and it eventually disappeared from the scientific literature.

I conducted a survey of over 1,000 people and asked each person to choose a picture, like those above, that best described his/her writing hand position. Only 8% of right-handers chose the inverted position while 50% of left-handers indicated an inverted handwriting style.  Percentage wise, why are so many left-handers inverted writers?

The technical aspects of producing cursive writing with the left hand may answer this question. When a left-handed writer uses the inverted position, the hand is positioned above the line of writing. A left-hander can pull rather than push the pen across the paper, avoid smudging ink and see what is being written. When the left-handed straight position is used, the hand moves across the line of print, smudging ink and hiding the words on the page. Photos of stained left hands caused by using the left hand in the straight position to write or draw are common posts on Facebook pages. Cursive script with a rightward slant is also more easily produced by a left-hander using the inverted writing posture. Interestingly, when right-handers are asked to write with a leftward slant, they switch from the more common right-handed straight writing position to one that is inverted.

The observed frequency of the inverted writing posture also varies with sex and age. Males and younger people are more likely to write with the inverted position than females and older adults. However, the causes of these rate variations are unclear. Rates of handwriting inversion also increase among children of parents who write in this style, a fact that suggests children may model the handwriting style they see being used by a parent.

Several former Presidents of the United States are or have been left-handed. The photo below shows the left-handed inverted and straight writing postures as one might see them in the real world rather than in diagrams.