The synthetic self

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What is the self? The human condition is defined by our awareness that we are distinct from the world, that we are, in some way, the same person from day to day, even though our bodies change, and that the people around us are also selves. But we still do not really know what we are. As William James explained more than a century ago, the dual nature of the self lies at the heart of the mystery – the self is this most unusual thing, in that it is both the perceiver of itself and the content of what it perceives. Right now, for instance, ‘I’ can sense ‘my’ fingers as they type. I can also see a screen on which my words appear, and, if I choose, I can focus instead on the rims of my glasses, which move as my head moves. Interestingly, ‘my’ can refer not just to body parts but to things I wear, think or do. Although the skin is an important boundary between self and not-self, the self is more than just the physical body – it is also a set of ideas about who and what I am.

With the advent of generative artificial intelligence (genAI) that can converse fluidly in the first person, people are asking whether such AIs might someday have a sense of self. Indeed, might they have one already? (OpenAI’s GPT-5, perhaps reassuringly, says it does not.) This question is hard to answer for several reasons, but particularly because we still lack a good understanding of the human self. Significant progress is being made, however, through philosophical, psychological and neuroscientific investigations, and most recently by an approach that I and others have been exploring – the attempt to create or synthesise a sense of self in robots.

Based on what we have learned, I believe a foundational aspect of the human self is that we have physical bodies, and that our experience emerges from a fundamental distinction between what is, and what is not, a part of the ‘embodied’ me. If this is true, then a disembodied AI could never have a sense of self similar to our own. However, for robots that inhabit our physical world through a body – even one quite different to our own – the bets may be off.

To understand the motivation for building synthetic selves, we first need to explore how philosophers and scientists have sought to interrogate the human self’s nature. One part of the puzzle is that I feel as though there is a centre of experience, somewhere in my head and behind my eyes. Although it is tempting to see this as the seat of the ‘I’, this turns out to be an unhelpful idea since, as the philosopher Daniel Dennett points out in Consciousness Explained (1991), this invites an infinite regress of inner perceivers. Indeed, contemporary philosophers and neuroscientists are largely in agreement that there is no localised, unchanging, inner ‘I’ somewhere inside my head. This doesn’t mean we should abandon the idea of selves as unscientific or treat the self simply as an illusion or a purely social construct. Instead, we should find a better explanation.

If the self is not a localised inner perceiver, then what is it, and how are we to reconcile the two sides of James’s self, one of which is the perceiver of the other? One way to start to answer this question is to deconstruct the self. For instance, we can ask what are the different psychological phenomena that relate to, or demonstrate, selfhood, and where and how do they rely on specific brain regions or networks. In this way, the human self can be deconstructed, understood, and then reconstructed from its various parts.

To begin with, consider that some patients in neurological clinics have been found to have a disordered sense of body ownership, where they regard a hand or limb as not their own. Typically, these patients have been found to have endured damage to the right-hand side of the brain in a specific region around the border of the temporal and parietal cortices. Patients with schizophrenia, meanwhile, may show disorders of agency whereby thoughts or actions are experienced as being controlled by someone else. Current theories point to brain networks that predict the sensory outcomes of your own actions, suggesting that these are altered in these patients. Damage to the insular cortex, one of the oldest cortical regions that is deeply involved in interoception (processing signals from the body), can lead to a sense of emotional disconnection from the self, and is implicated in the self-related disorders of depersonalisation or derealisation. Other forms of damage, for example to the temporal and frontal cortices of the brain, can impact the experience of the self as enduring in time, or the capacity to see the world from another person’s perspective.

Our nervous and sensory systems are encapsulated within our bodies and skulls

Another approach to deconstructing the self is to ask: how do these different phenomena emerge during early childhood? Let’s begin with the infant self. Although we cannot question infants directly, developmental psychology has found ways to probe self-perception in newborns. The evidence we have so far suggests we are each born with a basic self/other distinction – knowing what is, and what is not, part of our body. We also rapidly gain an understanding of our own agency, and when we have caused something to happen. However, the experience of the self as persisting in time is something that emerges much more gradually, as is our ability to conceive of others as having selves. Indeed, it may not be until age four or five that children have a sense of self that begins to resemble what we experience as adults.

Of the many important changes during development, the acquisition of language and of culture are central in shaping our adult experience of self. Indeed, at the conceptual level, the mature sense of self derives in part from ideas and beliefs about ourselves that we abstract from memory or acquire from others. This ‘narrative’ aspect of the self is the one on which notions of human identity typically depend, and it also emerges in the story we tell ourselves and others about who we are.

That there are different, and perhaps simpler, experiences of self in infancy, has led philosophers, including Dennett and Shaun Gallagher, to define a ‘minimal self’. This involves just the senses related to body ownership and agency, with no awareness of the self as persisting in time, or as something that can be thought about (self-reflection). The neuroscientist Jaak Panksepp and the neurologist Antonio Damasio each suggest that something similar to this minimal self arises from activity in sub-cortical areas of the human brain. These are some of the earliest brain regions to mature in newborns. These are also parts of the brain that have changed less in evolution than the cerebral cortices, and so are similar in other vertebrate animals. In other words, other animals with a backbone........

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