The Unwritten Self

X and C brain.gif

"A world without memory is a world of the present," Alan Lightman wrote in Einstein's Dreams. "The past exists only in books, in documents. In order to know himself, each person carries his own Book of Life, which is filled with the history of his life...Without his Book of Life, a person is a snapshot, a two-dimensional image, a ghost."

Most people would probably agree with Lightman. Most people think that our self -knowledge exists only through the memories we have amassed of our selves. Am I a kind person? Am I gloomy? To answer these sorts of questions, most people would think you have to open up some internal Book of Life. And most people, according to new research, are wrong.

Neuroscientists would call Lightman's Book of Life episodic memory. The human brain has a widespread system of neurons that store away explicit memories of events, which we can recall and describe to others. Some forms of amnesia destroy episodic memories, and sometimes even destroy the capacity to form new ones. In 2002, Stan B. Klein of the University of California at Santa Barbara and his colleagues reported a study they made of an amnesiac known as D.B. D.B. was 75 years old when he had a heart attack and lost his pulse. His heart began to beat after a few minutes, and he left the hospital after a few weeks. But he had suffered brain damage that left him unable to bring to mind anything had done or experienced before the heart attack. Klein then tested D.B.'s self-knowledge. He gave D.B. a list of 60 traits and asked him whether they applied to him not at all, somewhat, quite a bit, or definitely. Then he gave the same questionnaire to D.B.'s daughter, and asked her to use it to describe her fater. D.B.'s choices significantly correlated with his daughter's. D.B.'s Book of Life was locked shut, and yet he still knew himself.

A few other amnesiacs have shown a similar level of self-knowledge, but it's hard to draw too many lessons from them about how normal brains work. So recently Matthew Lieberman of UCLA and his colleagues carried out a brain-scanning study. They wanted to see if they could find different networks in the brain that make self-knowledge possible. They also wanted to see if these networks functioned under different circumstances--for example, when thinking about ourselves in very familiar contexts and unfamiliar ones.

They picked two groups of people to test: soccer players and improv actors. They then came up with a list of words that would apply to each group. (Soccer players: athletic, strong, swift; actors: performer, dramatic, etc.) They also came up with a longer list of words that applied specifically to neither (messy, reliable, etc.). Then they had all the subjects get into an fMRI scanner, look at each word, and decide whether it applied to themselves or not.

The volunteers' brains worked differently in response to different words. Soccer-related words tended to activate a distinctive network in the brains of soccer players, the same one that actor-related words switched on in actors. When they were shown words related to the other group, a different network became active. And, as Lieberman and his colleagues report in an upcoming issue of the Journal of Personality and Social Psychology, it just so happens that they had predicted precisely which two networks would show up in their scans. (Here's the full pdf on Lieberman's web site.)

When people were presented with unfamiliar words, they activated a network Lieberman calls the Reflective system (or C system for short). The Reflective system taps into parts of the brain already known to retrieve episodic memories. It also includes regions that can consciously hold pieces of information in mind. When we are in new circumstances, our sense of our self depends on thinking explicitly about our experiences.

But Lieberman argues that over time, another system takes over. He calls this one the Reflexive system (or X system). This circuit does not include regions involved in episodic memories, such as the hippocampus. Instead, it is an intuition network, tapping into regions that produce quick emotional responses based not on explicit reasoning but on statistical associations. (The picture I show here is a figure from the paper, with the X and C systems mapped out.)

The Reflexive system is slow to form its self-knowledge, because it needs a lot of experiences to form these associations. But it becomes very powerful once it takes shape. A soccer player knows whether he is athletic, strong, or swift without having to open up the Book of Life. He just feels it in his bones. He doesn't feel in his bones whether he is a performer, or dramatic, and so on. Instead, he has to think explicity about his experiences. Now D.B.'s accurate self-knowledge makes sense. His brain damage wiped out his Reflective system, but not his Reflexive system.

This research is fascinating on its own, and even more so when you think about the evolution of the self. Judging from the behavior of humans and apes, I'd guess that the Reflective system seems to be far more developed in us, while apes may share a pretty well developed Reflexive system. Does that mean that a Reflexive self existed before a Reflected one? Is the self we see in the Book of Life a recent innovation sitting an ancient self that we can't put into words? And does that mean that chimpanzees have a Reflexive self? Is that enough of a self to warrant the sort of rights we give to humans because they are aware of themselves?


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Research into the self and the perception of self is always interesting. I have not read the original, but I think perhaps based on your account, that it is probably misleading to suggest that the sense of self is not associated with memory. The reflexive system depends on memory as well, even if not memory of specific events. I think the experiment may not measure what it is intended to measure, or the conclusions may not be supported by the type of measurement made. It is not obvious to me that associating words with one's personality is exactly the same as one's own sense of self. I could imagine that the mental process would involve other types of systems, and that the sense of self itself is not necessarily associated with that system. Anyway, I think calling one system "intuition" rather than memory is making a distinction without a difference.

D.B was unable to consciously access memories from before his stroke. He was unable to demonstrate prior memory to an observer.
My mother's 90 and has many of the age-related symptoms of memory dysfunction common in the elderly. But she has moments of accurate clear retrieval, sometimes of things and events decades back, sometimes days. I'm convinced it's access that's being lost, more than stored memory itself.
To an external observer they're the same, of course.
There's an assumption of non-existence based on the absence of proof.
This attitude was the cause of the long-held dismissive attitude most scientists took toward the consciousness and long-term memory of infants, and toward the consciousness and ability to feel emotional pain of laboratory animals.
It still is, unfortunately, all too often.

By vernaculo (not verified) on 02 Sep 2004 #permalink

It's interesting that the 'reflexive' system, though apparently intuitive and non-explicit, is able to respond so effectively to words. It must be able to read (or draw on the support of another system which can read)- but you would have thought that reading was a prime example of explicit thinking.

I wonder if the examples of reflective thinking could be influenced by a particular state of mind or body. Someone who characteristically has been messy all their life is asked to thoroughly clean a room or organize a drawer or something, then they are asked whether they are messy or not. I wonder if the immediate 'clean' actions of the person would override their past as a messy one. One would think there would be more evolutionary advantage to an intuition system that ties into the most current state of mind or body.

By Mike Price (not verified) on 11 Sep 2004 #permalink

The relation of words to one's idea of themselves seems so psychosocially loaded that I'm not sure how one can assume that there is prior self- knowledge living on in the amnesiac.

Wouldn't every moment of life after the amnestic event be an opportunity to re-learn what words applied to one's self, as commonly socially construed? Perhaps I'm {quiet|obnoxious|assertive} now, and if I forgot that I was (socially construed) this way, I'd have every opportunity to re-learn it after the event. This argument of course depends on how long after the event the testing was done; I can't access the full article.

What about a brain injury that causes both memory loss and personality change - would the patient show continued awareness of his prior self-knowledge? I bet not. What I'm saying is that it seems difficult to tease apart any prior knowledge that the patient has retained, and the fact that during every waking moment, the patient is intuitively learning about himself again from his interactions.

By outrigger (not verified) on 12 Sep 2004 #permalink