Cerebral lateralization during handwritten and typed word generation: A
functional transcranial Doppler ultrasound study in left- and
right-handers.
Abstract
The neural underpinnings of written language, similarly to the neural
underpinnings of oral language, are left-lateralized. However, cerebral
lateralization for written language has only been studied using
handwriting tasks; the cerebral lateralization of keyboard typing, a
popular alternative means of writing, has not been explored. Therefore,
it remains unanswered whether handwriting and keyboard typing follow
similar cerebral laterality patterns. The aim of the present
preregistered study was to investigate cerebral laterality during typing
versus handwriting and to further examine the presence of handedness
differences. We hypothesized that: i) cerebral lateralization will not
differ between the two methods of writing after movement correction
(i.e., after subtracting the control condition from the main task); and
ii) cerebral lateralization of both handwriting and typing will be
weaker in left-handers compared to right-handers. In order to assess
cerebral laterality, we employed functional transcranial Doppler (fTCD)
ultrasound, which allows for a reliable assessment of cerebral
laterality during language production tasks and is unaffected by
movement, such as the movement generated during typing and handwriting.
Twenty-four left-handers and 30 right-handers underwent fTCD while
performing written word generation either by handwriting or by typing on
a computer keyboard. We found evidence of an absence of a difference
between the two methods of writing after movement correction. However,
we did not find conclusive evidence for either a difference or an
absence of a difference in the cerebral lateralization during either
method of writing between left-handers and right-handers.