We used to believe that we are either predominately left brained (rational) or right brained (creative). This idea is hard to dismiss even though scientists have proven that this is not how the brain works.
What scientists now understand is that every thought is contained on both sides of the brain, However, the perspective of each side of the brain is different from the other.
The Left side of the Brain: Detail to Big Picture
For example: 2 + 2 = 4
The Right side of the Brain: Big Picture to Detail
For example: 4 = 2 + 2
For optimum effectiveness, these double memories (or thought-trees) have to work together in synergy and harmony.