58 A Programmer’s Guide to the Mind
and that the right hemisphere functions associatively. Researchers may
disagree over the precise nature of this processing, but the basic distinction
is well established. Therefore, we can immediately conclude that Mercy
and Perceiver thought are associated with the right hemisphere and
Teacher and Server strategy with the left.A
Second, when we look closer at the function of each hemisphere we
find another clear division, between the front and the back of the cortex. At
the boundary between these two regions is the primary motor-sensory strip,
a band of cortex which is responsible for body sensation and muscle
movement. The region behind this strip interprets and manipulates
information which comes in from the external world, while the area in
front of this strip—the frontal lobe—is a more nebulous domain housing
the internal world which makes us human. Again, there is no question over
this distinction and these functions. It is general knowledge. Thus, we
conclude that the mental processing of each of the four simple styles is
divided into the two categories of sensory thought and internal world.
Finally, if we examine the back of each cortex, we find one more clear
division, between top and bottom. The bottom half is called the temporal
lobe, while the top is labeled the parietal lobe.B The function of these two
lobes is also well known, and it has also been firmly established that the
right parietal lobe has a different purpose than the left parietal lobe, and
that the right and left temporal lobes also differ in function.
When we get to the front half of each cortex, though, the situation
becomes somewhat confused. On the one hand, neurology has discovered
that there is a clear distinction between the top of the frontal lobes (the
dorsolateral region) and the bottom of the frontal lobes (the orbitofrontal
cortex). The exact boundary between these two areas may be uncertain, but
there is no question about the separation between them.
So far, so good. The only problem is that information about the frontal
lobes usually lumps together corresponding regions in the left and right
hemispheres. Therefore, while it is easy to compare the function of the
bottom half (or inferior) of both frontal cortices with the top half (or
superior) of both frontal cortices, it is much harder to find information
which makes a distinction between the left dorsolateral frontal and the
right dorsolateral, or between the left orbitofrontal and the right
orbitofrontal cortices.C
A In this book we examine only the simple styles.
B The very back of the cortex, the occipital lobe, behind the temporal and
parietal lobes, is responsible for analyzing visual information.
C We will be using two different terms when discussing the bottom half of
the frontal cortex. The inferior frontal cortex refers to the entire lower half,
whereas the orbitofrontal cortex is a more specific region limited to the
bottom of the bottom half.