Shortly afterwards, a German neurologist, Carl Wernicke, identified another part of the left hemisphere primarily concerned with language comprehension. The only direct tests for speech lateralization are too invasive to use on healthy people, so most of what we know in this area comes from clinical reports of people with brain injuries or diseases. The more one knows about the neurological mechanisms underlying language abilities, the more complicated these issues become. Most people in our society define handedness as the hand you use for writing. Within the scientific community, the vagueness of this term has led to much debate.
Researchers define handedness based on different theoretical assumptions.
Some think there are two different kinds of ambidexterity. Some think that handedness should not be lumped into 2 or 3 or 5 categories, but rather measured along a scale of a continuum. My work attempts to resolve some of these issues. We are still trying. Test was introduced in the 1960s.