Supporting Evidence: Split-Brain Studies
The figure illustrates a man slapping his wife with his left hand while his right hand tries to stop his own left hand, denoting Alien Hand Syndrome, a very rare condition among patients with communication problems between hemispheres (e.g. split-brain), where one of the hands executes goal directed actions without the patient having any control over it.
The fact that both hemispheres in the human brain work independently in different ways was discovered for the first time by Professor Roger Sperry and Professor Michael Gazzaniga in the 1960s. The discovery was based on their experiments with patients whose corpus callosum, a band of fibres connecting both hemispheres, was surgically cut to cure extreme forms of epilepsy.
Mechanisms underlying outcomes of all their experiments on split brain patients, as they are called, are revealed by Dichotomized Operating System Model (DOS Model), a model on which the explanations given till now are based. The DOS model reveals what we call mind is not something fuzzy and cannot be explained or studied by science, as it is generally perceived, but is a causal outcome of a group of interconnected mechanisms running in the brain (introductory video).
William James, Philosopher and Psychologist (1842 –1910)
William James, known as the father of American psychology, believed that there were two different kinds of thinking: associative and true reasoning. His explanation of associative thinking is the same as the role played by left hemisphere in the DOS model, i.e. without drawing on past experiences and true reasoning is the same as the role played by right hemisphere, i.e. using past data in the DOS model.
Thinking, Fast and Slow by Daniel Kahneman
The model is also confirmed by observations of Nobel Laureate Dr. Daniel Kahneman, author of "Thinking Fast and Slow", who discovered that there are two systems that govern how the mind works, system 1, which represents the instinctual mental events that allows quick decision making with little mental energy, which we are not conscious of, and system 2, which represents the conscious self that makes choices and decides what to do.
The system 1 in Dr. Kahneman’s observations is the same as left hemisphere in the model, which allows quick decision making, as it is capable of parallel processing, and uses little mental energy, as logical processing uses much less computing power than multiple instances of hierarchical database search and retrieval in the serial environment of the right hemisphere, and system 2 is the same as right hemisphere in the model, which explains the conscious self and how it makes choices and decides what to do.
The Master and His Emissary by Iain McGilchrist
Also confirming the model are observations of Dr. Iain McGilchrist, author of "The Master and his Emissary", who has observed that the left hemisphere focuses on details of experiences, which are sent to the right hemisphere, which then become integrated with it and enrich the wider picture (which is the basic premise of the DOS model). He also mentions that origin of all experience is in the right hemisphere and that it is responsible for our personal and social relationship with others. Mechanisms underlying these and other observations by Dr. McGilchrist are causally explained by the model.
Although such and many other elaborate accounts confirm the DOS model, they are chiefly based on observations. DOS model is the first and only account of the human mind which is purely based on causation.