You think, therefore you are. But what are you?
One of the most elusive concepts throughout the long history of philosophy and shorter life of neuroscience is actually the thing that feels closest to us: the self. How do you define it, how do you sense it? This "self" that embodies all of our thoughts, ambitions and actions—where is it? Is it even one seamless entity, or could it break into other, smaller or different subselves?
Science writer Anil Ananthaswamy examines the self from every angle in his new book, The Man Who Wasn't There: Investigations Into the Strange New Science of the Self. He explores whether modern knowledge of the brain can offer any clue about the origin or building blocks of the self. He visits patients whose unique stories break apart the common idea of the self: Those with Cotard's syndrome, who believe they don't exist; those with Alzheimer's disease, who don't quite remember who they are; those who see themselves from outside in an out-of-body experience, and those who don't feel they are quite whole unless they remove parts of their bodies.
Writing from India, Ananthaswamy explains what he learned about the self on this journey and what mysteries still remain.
Is the self one solid entity, or does it have multiple facets, each made by different mechanisms?
Our sense of self feels to us as being one solid entity, but upon close examination, it's clear it has many facets. For instance, there is the sense we have of being anchored in a body, of occupying a volume of space that's the body, of having a sense of ownership of our own body, and a feeling of perceiving the world from within our heads, where every perception has a sense of ' mineness' to it. All these comprise the bodily self.
We also have a sense of being a narrative, a story that spans time, from our earliest memories to some imagined future. This is the narrative or autobiographical self.
The more finely you examine the sense of self, the more facets you find.
In the chapter on Alzheimer's disease you tell us stories of several people with this condition. What does this disease teach us about the role of memories in constructing one's self, and how does the self come apart as the disease progressively erases our memories?
Our narrative or autobiographical self is dependent on memory—whether this is explicit memory that requires conscious recall or procedural memory, which is involved in learning and remembering how to do things such as riding a bicycle. So, in order to have a narrative self, our memory systems should be working well, whether cognitive or embodied. Alzheimer's disease impacts short-term memory formation. Initially, the condition stops our narrative self from growing further, since new memories are not getting incorporated into the autobiographical knowledge about oneself. Unfortunately, as the disease progresses, it begins eating away at earlier memories too, until one is unable to recognize one's closest friends and relatives. There's also serious cognitive decline. The result is a relentless destruction of the narrative self.
As Alzheimer's eventually leads to death, these stories are inherently emotional. But it seems that what many patients (and their caregivers) are really concerned about is that they will eventually cease to be themselves. Is it possible that the idea of losing the "self" is even more distressing than the idea of death? If so, why do you think that is?
By definition, the self is something that needs to be coherent; any threat to its integrity is scary. A threat to the bodily self will spur us to action. Similarly, threats to our narrative self will also demand attention. It's in the nature of the self. So, it's possible and entirely reasonable that for some of us, the idea of losing oneself is scarier than death itself.
How can case reports of extremely rare conditions such as Cotard's syndrome help us understand more about something as universal as the self?
Neuropsychological conditions that perturb the self or change how one feels about oneself—whether rare like Cotard's syndrome (in which patients often feel as if they doesn't exist) or relatively common like schizophrenia (in which people can feel like they are not the agents of their own actions)—are windows on the self. They give us a glimpse into the constructed nature of much of our sense of self. If we think about how we have learned about brain functions, much of our understanding has come from studying people who, sadly, suffered strokes, or had tumors, or brain trauma, sometimes causing loss of specific functionality, such as language ability, or certain motor skills. By correlating the loss of functionality with the damage to brain tissue, neuroscientists have been able to understand a lot about the role of different parts of the brain. Neuropsychological disturbances of the self play a similar role. They help us understand how our sense of self is put together.
Does the body also play a role in the construction of self? Or is it all in the brain? If the body does have a role, what is it and how can it go wrong?
The body is central to our sense of self. It can be argued that during the course of evolution, it's the bodily self—the sense of being a body that can be controlled and attended to—that must have arisen first. Many animals likely have a sense of the bodily self. The body grounds our sense of self. The more evolved narrative self is built upon the bodily self. There's plenty of evidence that disturbances of the bodily self can have cognitive consequences, and even impact our narrative self. For instance, experiments have shown that when someone is having an out-of-body experience (OBE), it impacts his ability to correctly recall a sequence of events that happened during the OBE. In other words, being out of body can impact episodic memory formation, and hence the narrative self. There's also some evidence that the symptoms of depersonalization disorder—in which people feel estranged from their own emotions—can sometimes be temporarily alleviated by engaging in tasks that require paying intense attention to the body.
So, it's not just the brain. It's wrong to think of the brain as being separate from the body, as if it's some puppet master sitting outside the body. Brain and body are inextricably linked—and work in concert to create our sense of self.
In the chapter "The Man Who Didn't Want His Leg," you accompany a man on his journey to Asia to find a surgeon who would amputate his leg. Did this experience change your mind about the concept of a healthy body and mind or the concept of the self? Does neuroscience provide any answers as to why some people feel they have a foreign limb?
Yes, neuroscience does have a hypothesis about why some people feel like some part of their body does not belong to them. The essence of the idea goes something like this: the brain's job is to keep the body in physiologically viable state, optimal for survival. In order to do its job, the brain creates a model of the body, or put another way, creates maps of the body, and various body parts. When we sense our body, we are actually sensing the information in these maps. Normally, the maps and the actual physical body should match up, so sensing the information is akin to perceiving the physical body. But occasionally, this mapping process goes awry. We can end up with a mismatch between a body part and its representation in the brain, and this might lead to someone perceiving that body part as not belonging to self.
Talking to people who suffer from such conditions did change my idea of what it means to have a bodily self. We take our sense of the body as being fixed, immutable. Actually, it's anything but. The brain works very hard, moment-by-moment, to integrate both internal and external sensations and create our sense of bodily self. But it's malleable, and can be disrupted, sometimes with heartrending consequences.
Under what circumstances people might see their doppelgänger? What's the connection between that and out-of-body experiences? What does new research say about these seemingly paranormal experiences?
Doppelgänger experiences and out-of-body experiences are both so-called Autoscopic phenomena (from Greek: autos means 'self' and 'skopeo' means 'looking at'). Both seem to involve centers of the brain that are involved in what neuroscientists call multisensory integration—the processes in the brain that integrate various sensations such as vision, touch, proprioception and vestibular signals, to create our sense of being in-body. When this integration is disrupted, say, because of a lesion in the relevant brain region—people can experience seeing their doppelgänger. The new research is suggesting that there is nothing paranormal about these experiences: they are caused by aberrant neural processes.
Thinking a lot about these topics can induce transient shifts in one's mind. Did you experience anything peculiar during your research and writing? Perhaps, moments in which you deeply questioned your own being and self? Now, after all the extensive research you conducted for writing this book, has your idea of the self changed? In what ways?
On a personal level, I have been deeply questioning the nature of my own self for a while, influenced mainly by the philosophies of India. Both Buddhist and Hindu philosophers have argued for millennia that the self that we take to be a solid entity is actually not so. The writing of this book—which involved talking to many neuroscientists, philosophers, doctors and people suffering from neuropsychological conditions—led to the realization that neuroscience is not at odds with such ideas about the self. So, while there were no specific moments when I questioned my own self and being any more deeply than I already did, the effort to write this book has only reinforced the feeling that our well-being depends on being able to see the illusion of the solid self and not being attached to it. And it led me to appreciate that the essential mystery of who we are—the "I" that can either be attached to all the aspects of the self or not—still remains a mystery. Who or what is that "I"?