The text says:
“I am the left brain. I am a scientist. A mathematician. I love the familiar. I categorize. I am accurate. Linear. Analytical. Strategic. I am practical. Always in control. A master of words and language. Realistic. I calculate equations and play with numbers. I am order. I am logic. I know exactly who I am.”
“I am the right brain. I am creativity. A free spirit. I am passion. Yearning. Sensuality. I am the sound of roaring laughter. I am taste. The feeling of sand beneath bare feat. I am movement. Vivid colors. I am the urge to paint on an empty canvas. I am boundless imagination. Art. Poetry. I sense. I feel. I am everything I wanted to be.”
The lateralization theory originated from Roger W. Sperry’s work, the scientist who won the Nobel Prize in 1981 for defining the left/right division and using it for healing certain disorders. Nowadays this severe dichotomy has been discarded, even though they’ve agreed that there are abilities related to a certain side of the brain.
Mercedes doesn’t say which side they are, insinuating that they are both. I guess that’s the key of all this, being a combination of the two sides :)