Hemispheric differentiation is a popular theory that describes people or behaviors as either "left-brained" using a logical, impersonal, detail-oriented mind, or "right-brained" using a second mind that is more emotional, relational, and expansive. The cortex, which is the top layer of the human brain, does have left and right halves that are separated by a deep canyon called the central sulcus, and each half of the cortex can operate semi-independently. Hemispheric differentiation suggests that differences in behavior arise from different modes of functioning in the left versus right hemispheres of the cortex. TMT would agree in some ways with this analysis, in suggesting that people do have two minds with sometimes divergent goals and characteristically different ways of approaching the world. But TMT locates humans' two minds at different levels of the brain — neocortex versus cingulate cortex and deep-brain structures — rather than in a division between t...