From "Finding Your FACE: a Brain-Based Personality Model".

With respect to brain dominance, and specifically Left-Brain vs. Right-Brain Dominance we have to clarify a few things.

There has been much debate about “brain dominance” or “right-brain vs. left-brain”. And this vernacular has absolutely led to confusion. To clear up some of that confusion, we need to go back to the work of Roger W. Sperry.

Sperry was a psychobiologist and a Nobel Prize winner who did some amazing research on the brain back in the 1960’s. What his research revealed was that the two hemispheres of the brain function very differently.

Specifically, he observer that the left brain is more auditory/verbal. It’s better at order and sequence, linear thinking, basic mathematics, organizing by features and characteristics.

Conversely, the right brain is more visual-spatial. It’s more creative and intuitive. The right brain is better at visualization and imagining, big picture thinking, and recognizing patterns and rhythms.

Now given the obvious fact that people have different strengths and weaknesses which correspond to the left brain and right brain functions, a team of neuroscientists set out to see if one hemisphere of the brain actually developed more or faster than the other.

And after conducting MRI’s on over 1,000 people, they found NO EVIDENCE whatsoever that there was any appreciable different in physical development of either hemisphere.

So, to be clear, physically speaking, there is NO SUCH THING as left-brain or right brain dominance. Structurally, physiologically, your left hemisphere and your right hemisphere are exactly the same.

However, human being are NOT a one-size-fits-all. If the two hemispheres are structurally identical, how can there be such a wide variety in human behavior and apparent ability?

The reason is NOT in the physical STRUCTURE of the brain, it’s in the USAGE or ACTIVITY going on in the various parts of the brain.

Years after the work of Sperry, Dr. Daniel Amen conducted over 10,000 SPECT scans (Single-photon emission computed tomography) and confirmed that while the hemispheres are physically similar from person to person, the activity within and between the hemispheres can be radically different from person to person.

Dr. Amen’s analysis of brain activity was so detailed, he was able to identify seven (7) distinct types of ADHD (Attention Deficit Hyperactivity Disorder).

The conclusion here is that for most people the left and the right hemispheres are physically identical.

However, the activity within those hemispheres and between those hemispheres can be radically different. And for the purposes of personality and behavior, it is the activity of those brain functions upon which we will focus.