Alien Hand Syndrome and the Disunity of Mind

The mind is not one stream of information, but many.

Posted Aug 29, 2013

My friend and Huffington Post Blogger Dave Pruett is a mathematician turned philosopher who writes about the interface between science and what might be termed more mystical or parapsychological approaches to understanding mind and consciousness. Whereas I adopt a more naturalistic approach to consciousness and view conscious experience as arising from the flow of and integration of neuronal information, Dave views the brain as potentially being more like a vessel that receives inputs from a transcendental plane. Although there are many potential areas of fruitful discussion that might stem from our differing positions, he made the following comment on a recent blog that I think is worth reflecting on.

At issue is the relationship between "brain" and "mind." Brains are easy to locate. The human brain is the wet, convoluted organ of about three pounds that resides in the cranial cavity of the skull. It is a clearinghouse for sensory stimuli, the seat of the emotions, the control center for complex movement, the processor of language, and presumably, the originator of thought. Mind, on the other hand, is the faculty of conscious, subjective experience: the "ghost in the machine." If free will exists, mind is the seat of free will. "Brains are automatic, but people are free," asserts at least one neuroscientist. The chief attribute of the brain is its extraordinary complexity. The chief attribute of mind is its inexplicable unity. Mind and brain are related, but how remains enigma.

I agree with Dave that the mind should not be confused with the brain (see here), although we might have slightly different conceptions about where the dividing line would be. I also agree that the unity of our conscious experience is both a major feature of it and a mystery. The unity of conscious is such a well-known and mysterious feature that it has a name in neurobiology called “the binding problem”.

Despite these agreements, I want to offer some thoughts about his claim that the “chief attribute” of the mind is its unity. According to my conceptual map of these terms, it is very important to be clear that although consciousness emerges out of mind, mind is not synonymous with consciousness. Indeed, as Freud richly observed and modern cognitive science has clearly documented, there are many sub- and non-conscious mental operations that are part and parcel to the concept of the mind as I (and most psychologists) conceive it.

However, even if we restrict ourselves to the narrower term consciousness, the unity of consciousness, although a major attribute, can also be broken down to reveal elements and pieces. For starters, let’s note that the relationship between conscious and subconscious processes are not always so clear cut. Consider, for example, an everyday drive to work. If you are like most people, a regular trip to work can become so habituated that it is hard to say exactly what was part of your conscious experience and what were habituated actions that were just procedures performed outside of awareness. Are you aware of putting the key in the ignition, putting on your blinker changing lanes? We can also begin to see consciousness as less than fully unitary when we consider altered states of hypnosis, subliminal processing, dreaming, various forms of drug induced altered states, as well as psychopathological conditions like hallucinations associated with schizophrenia and Dissociative Identity Disorder (formally known as multiple personality disorder).

A potential response here is that what Dave is referring to is the unity of conscious experience. The first person sense of awareness that is experienced as a whole. But even here there is an important distinction to make. My perspective is that there is not a single stream of consciousness in humans, but multiple streams that are (somehow) bounded together.

The most basic separation of conscious streams I emphasize is the distinction between verbally mediated self-consciousness and experiential consciousness (or sentience). This is a separation that you are already very intimately familiar with. Speak out loud to someone. Then internalize the speech. Then speak out loud again. As you shift back and forth, you are sharing the verbally mediated portion of your consciousness, which can go from being private to public and back again. The miracle of human language is that it allowed for a system of information flow to connect conscious minds together. The inventions of writing and the internet have built on this capacity, such that I am now sharing the words inside my head through time and space and they are entering your conscious mind as you read this at a different time than when I constructed it.

Perhaps the best evidence for the idea that consciousness is made up of multiple streams of information comes from studying split brain patients. Split brain patients are (generally) individuals who suffered severe epilepsy. Beginning in the 1950s and 1960s, neurosurgeons began to cut the corpus callosum in the brains of some patients with severe seizures in an attempt to minimize the spreading of the out-of-control neural firing. The corpus callosum is the set of neural fibers that connects the two hemispheres of the brain, and thus when it is cut, communication between the two hemispheres is broken (see here). These patients—who came to be called split-brains—generally lived normal lives but careful research revealed some striking findings. If simple commands were flashed to the right hemisphere, such as "walk around" or "laugh," the patients would follow these commands (the right hemisphere does have rudimentary linguistic capacities). However, when asked to explain why they were performing these behaviors (e.g., walking or laughing), patients would make up a reason, and say "I am going to get a drink" or "Because you guys are so funny". In other words, their self-consciousness system justified the behavior in the absence of necessary information (explained here by one of the most famous researchers in the area).

Other even more dramatic examples emerged. For example, some patients would report a condition called ‘alien hand syndrome’, in which the left hand (guided by the right hemisphere) would seemingly act as if it were controlled by a mind of its own. A patient with alien hand might go into the closet to get a blouse, and find that both her hands would reach for separate garments, and a tragic-comic struggle between them might literally ensue! Even more dramatically, a case is reported here of a man being strangled by his alien hand.

One feature of split brain patients does get us back to Dave’s point. Despite the fact that they were clearly behaving based on separate streams of mentation, their experience was of only one consciousness. That is, such patients generally do not report conscious experience of what drives their left hand, except for some intuitive urge or sense (which, BTW, gets to the fuzzy line between conscious and subconscious experience). So, in that regard then, one of the chief attributes of experiential consciousness is its unity. However, as alien hand syndrome puts in dramatic relief, we should be very clear that the mind—and even human consciousness more specifically—is in fact made up of many different parts and streams.