There are often many ways of modeling the same thing. Models are inherently inaccurate, but the best are those which combine an acceptable degree of inaccuracy with a significant reduction in complexity. It’s obvious that the theorized output of a system depends on the model used to represent the system, but it’s nonetheless an important point. It’s a point that makes choosing a model akin to medical researchers brainstorming clinical trial designs or fiction writers selecting from an array of metaphors: each available option will alter the results in a unique way, will emphasize some aspect of the output.

And with that introduction, check out my drawings of arrows pointing towards and away from a brain.

This first image represents the brain functioning under normal conditions. The incoming arrows originating from the left represent sensory stimuli, the incoming arrows originating from the brain itself represent internal thoughts, and the outgoing arrows represent speech, muscle movement, or some other interaction with the external environment. The real attraction of using models is the ease of exploring the results of what would be prohibitively expensive, immoral, or physically impossible in the real world. For example, consider the drawing below, which represents the expected result of instantaneously placing the test subject in a sensory deprivation chamber.

The incoming arrows representing sensory stimuli have necessarily disappeared. The shock of the transition has also resulted in the absence of the arrows representing interaction with the external environment. The presence of internal thoughts is unchanged and, while the nature of the thoughts has probably changed in reaction to the new environment, this model doesn’t reflect that level of detail. The dashed lines and question marks shouldn’t be interpreted to represent the likely state of the test subject “what the hell just happened?” Instead, I drew them in to personify the brain receptors/order issuers who are normally occupied receiving/sending signals throughout the nervous system. This intermediate and unstable state leads to the final drawing, which exemplifies the adaptability of the brain in seeking to achieve a state approaching normalcy.

Visually, the coarseness of these models suggests that there is no difference in capability between the receptors/order issuers and those portions of the brain involved in internal thought. It follows, then, that increasing internal thoughts, as illustrated above, satisfies the question marks of the previous illustration by requiring the participation of both the receptors and order issuers. The outgoing arrows are included for good measure to account for the possibility of the subject beginning to talk to themselves after several hours in the chamber.