In most (97%) right-handed people language is controlled by the left hemisphere. Left-handers have a more even distribution of language in both hemispheres. In 19% this is concentrated in the left hemisphere, and in 68% it is concentrated in the right hemisphere, the remainder have language processing in both hemispheres.
Perhaps the most intriguing split brain research was with a patient of another pair of split brain researcher, Michael Gazzaniga and Joseph LeDoux, who had some limited language facilities in his right brain. This patient show marked preferences in responses from the two hemispheres. When asked, "What do you want to do?" the left hemisphere replied "draftsman", but the right hemisphere (using scrabble letters) replied "automobile race" .
Ned Herrmann is "Father of brain dominance technology". He drew on the work of Sperry and developed the theory brain dominance where people develop a dominant mode of thinking preference. These can range from an analytical "left brain" approach to "right brain" approaches involving pattern matching and intuitive understanding. These preferences have their roots in our genetic makeup and how it affects our underlying cognitive capabilities. For example left-right handed preferences have been observed in the womb. As we develop we tend to respond with our strongest abilities as these lead to quicker short-term rewards. This can create a positive feedback system that will strengthen those abilities. Eventually this can lead to a powerful preference for one style over the other and a dislike and discomfort for other modes of thinking.
Herrmann then went onto develop the four-quadrant model of cognitive preferences and a questionnaire called the Herrmann Brain Dominance Instrument (HBDI) , . The inspiration for this model came from dividing the brain into as four different systems with four preferred styles:
* A: Left cerebral hemisphere - analytical
* B: Left limbic system - sequential
* C: Right limbic system - interpersonal
* D: Right cerebral hemisphere - imaginative
However, Herrmann's system does not try to be an accurate model of the way the brain functions. Instead it should really be thought of as a model of different styles, partially inspired by the brain, but also the result of extensive questionnaires. As he refined his questionnaires four (rather than just two) separate clusters seemed to emerge which are reflected in the model. Considerable work has gone into testing the validity of this system with overall positive results.
A Quadrant: Analytical thinking.
* Key word: logical, factual, critical, technical and quantitative.
* Preferred activities: collecting data, listening to informational lectures, reading textbooks. Judging ideas based on facts, criteria and logical reasoning.
B Quadrant: Sequential thinking.
* Key word: conservative, structured, organised, detailed, and planned.
* Preferred activities: following directions, repetitive detailed homework problems, time management and schedules.
C Quadrant: Interpersonal thinking
* Key word: kinaesthetic, emotional, spiritual, sensory, feeling.
* Preferred activities: listening to and sharing ideas, looking for personal meaning, sensory input, and group study.
D Quadrant: Imaginative thinking.
* Key word: Visual, holistic, intuitive, innovative, and conceptual.
* Preferred activities: Looking at the big picture, taking initiative, simulations (what if questions), visual aids. Appreciate beauty of a problem, brainstorming.