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It is because our perceptions have the phenomenological character of “being real” that it is extraordinarily difficult to appreciate that, in fact, perceptual experiences do not necessarily—or ever—directly correspond to things that have a mind-independent existence. A chair has a mind-independent existence; chairness does not.
And our mission gathers pace when we consider that it is not only experiences of the world that are perceptual constructions. It’s time to ask who, or what, is doing all this perceiving.
It may seem as though the self—your self—is the “thing” that does the perceiving. But this is not how things are. The self is another perception, another controlled hallucination, though of a very special kind.
The more interesting problem is that of personal identity. Is the Eva on Mars (let’s call her Eva2 ) the same person as Eva1 (the Eva still in London)? It’s tempting to say, yes, she is: Eva2 would feel in every way as Eva1 would have felt had she actually been transported instantaneously from London to Mars. What seems to matter for this kind of personal identity is psychological continuity, not physical continuity.* But then if Eva1 has not been vaporized, which is the real Eva? I think the correct—but admittedly strange—answer is that both are the real Eva.
The idea that the self is somehow indivisible, immutable, transcendental, sui generis, is baked into the Cartesian ideal of the immaterial soul and still carries a deep psychological resonance, especially in Western societies.
Kant, in his Critique of Pure Reason, argued that the concept of the self as a “simple substance” is wrong, and Hume talked about the self as a “bundle” of perceptions.
Buddhists have long argued that there is no such thing as a permanent self and through meditation have attempted to reach entirely selfless states of consciousness.
What could it mean to be an individual self, when it turns out that one craniopagus twin can feel the other drinking orange juice? Being you is not as simple as it sounds.
the sense of personal identity—the “I” behind the eyes—is only one aspect of how “being a self” appears in consciousness.
There are experiences of embodied selfhood that relate directly to the body. These include feelings of identification with the particular object that happens to be your body—we feel a certain sense of ownership over our body that doesn’t apply to other objects in the world. Emotions and moods are also aspects of embodied selfhood,
Moving on from the body, there’s the experience of perceiving the world from a particular point of view, of having a first-person perspective—a subjective point of origin for perceptual experience which usually appears to reside inside the head, located somewhere between the eyes and slightly behind the forehead. This perspectival self
for personal identity to exist, there has to be a personalized prior history, a thread of autobiographical memories, a remembered past and a projected future. This sense of personal identity, when it emerges, can be called the “narrative self”.
The social self is all about how I perceive others perceiving me. It is the part of me that arises from my being embedded in a social network.
Just as experiences of redness are not indications of an externally existing “red,” experiences of unified selfhood do not signify the existence of an “actual self.” Indeed, the experience of being a unified self can come undone all too easily. The sense of personal identity, built on the narrative self, can erode or disappear entirely in dementia and in severe cases of amnesia,
The self is not an immutable entity that lurks behind the windows of the eyes, looking out into the world and controlling the body as a pilot controls a plane. The experience of being me, or of being you, is a perception itself—or, better, a collection of perceptions—a tightly woven bundle of neurally encoded predictions geared toward keeping your body alive. And this, I believe, is all we need to be, to be who we are.
It is not just body parts that can be experienced differently. The whole body—and the origin of the first-person perspective—can be affected too. In 2007, two papers appeared in the prestigious journal Science at almost the same time. Both described how new methods in virtual reality could be used to generate an “out-of-body-like” experience. The experiments were based on the rubber hand illusion, but now extended to the entire body.
“I see myself lying in bed, from above, but I only see my legs.” The common factor in cases like these is unusual activity in brain regions that deal with vestibular input (the vestibular system deals with the sense of balance) and that are also involved in multisensory integration. It seems that when normal activity in these systems becomes disrupted, the brain can reach an unusual “best guess” about the location of its first-person perspective, even while other aspects of selfhood are left unaltered.
These experiences are usually divided into autoscopic hallucinations—in which you see your surroundings from a different perspective—and heautoscopic hallucinations (also known as doppelgänger hallucinations)—in which you see yourself from a different perspective.
People have had real out-of-body experiences for millennia, but this does not mean that immaterial selves or immutable souls have ever actually left any physical bodies.
The aim of BeAnotherLab is to adapt body swapping technology into novel “empathy generation” devices.
Two participants put on headsets, and first look down at their laps, so that they see their partner’s body instead of their own. They then make a series of coordinated movements, following detailed instructions, and if they follow along closely enough, their new body will appear to respond to their commands, strengthening the experience of being the other. After some time, mirrors are held up, and each sees the mirror image of the other, as if it were himself or herself.
an entity experiences itself as continuous from one moment to the next, from one day, or week, or month to the next, and—to some extent—across an entire life span. These are the levels of selfhood at which it makes sense to associate the self with a name, with memories of the past, and with plans for the future.
Clive has immense problems recalling old memories (retrograde amnesia) and, especially, laying down new memories (anterograde amnesia). Remarkably, he seems to exist in a permanent present of between seven and thirty seconds.
The kind of memory Clive has lost is his episodic, autobiographical memory—memory of events located in time and space (episodic), including, most important, those events involving himself (autobiographical).
Memory is not the be-all and end-all of selfhood, but as this story tells us, and as many of us know through family and friends in the hinterlands of dementia or of Alzheimer’s disease, the persistence and continuity of self-perception is difficult to do without.
Perceiving the state of mind of another is a crucial ability for social creatures in all sorts of contexts and in all manner of societies. This ability—sometimes called “theory of mind”—is often thought to develop rather slowly in humans, but it comes to play a key role for almost all of us throughout our lives.
even when we aren’t ruminating on our social interactions, our ability to perceive others’ intentions, beliefs, and desires is always operating in the background, guiding our behavior and shaping our emotions.
Here, I want to turn the lens inward, to consider how the experience of being me depends, in a substantial way, on how I perceive others perceiving me.
The ability to infer others’ mental states requires, as does all perceptual inference, a generative model. Generative models, as we know, are able to generate the sensory signals corresponding to a particular perceptual hypothesis. For social perception, this means a hypothesis
I can understand what’s in your mind only if I try to understand how you are perceiving the contents of my mind.
If you exist in a world without any other minds—more specifically, without any other relevant minds—there would be no need for your brain to predict the mental states of others, and therefore no need for it to infer that its own experiences and actions belong to any self at all.
A striking but often overlooked aspect of conscious selfhood is that we generally experience ourselves as being continuous and unified across time. We can call this the subjective stability of the self.
We are becoming different people all the time. Our perceptions of self are continually changing—you are a slightly different person now than when you started reading this chapter—but this does not mean that we perceive these changes.
We live with an exaggerated, extreme form of self-change-blindness, and to understand why, we need to understand the reason we perceive ourselves in the first place.
We do not perceive ourselves in order to know ourselves, we perceive ourselves in order to control ourselves.
Self-perception is not about discovering what’s out there in the world, or in here, in the body. It’s about physiological control and regulation—it’s about staying alive.
For centuries, especially in Europe, the Great Chain of Being—or Scala Naturae—provided a stable template by which humans could understand their place in nature,
René Descartes did away with the many gradations of the Scala by cleaving the universe into just two modes of existence: res cogitans (mind stuff) and res extensa (matter stuff).
Our conscious experiences of the world around us, and of ourselves within it, happen with, through, and because of our living bodies.
My proposal is that we cannot understand the nature and origin of these conscious experiences, except in light of our nature as living creatures.
the familiar modalities of sight, hearing, taste, touch, and smell. These world-oriented varieties of sensation and perception are collectively called exteroception. Perception of the body from within is known as interoception—it is the “sense of the internal physiological condition of the body.”
Instead, they argued that emotions are perceptions of changes in bodily state. We don’t cry because we are sad, we are sad because we perceive our bodily state in the condition of crying. The emotion of fear, in this view, is constituted by (interoceptive) perception of a whole gamut of bodily responses set off by the organism recognizing danger in its environment. For James, the perception of bodily changes as they occur is the emotion:
While the specifics of this concern are still debated, a powerful response emerged in the 1960s with “appraisal theories” of emotion. On these theories, emotions are more than just readouts of changes in bodily state. They depend on a higher-level cognitive appraisal, or evaluation, of the context in which the physiological changes take place.
Of course, it might equally be true—and I suspect that it probably is true—that every emotion does indeed have a distinct embodied signature, with the fine details of their distinguishing features just being very difficult to detect.
emotional experiences depend on how physiological changes are evaluated by higher-level cognitive processes.
I called the idea “interoceptive inference”. Just as the brain has no direct access to the causes of exteroceptive sensory signals like vision, which are out there in the world, it also lacks direct access to the causes of interoceptive sensory signals, which lie inside the body. All causes of sensory signals, wherever they are, are forever and always hidden behind a sensory veil. Interoception is therefore also best understood as a process of Bayesian best guessing, just like exteroceptive perception.
Emotions and moods, like all perceptions, come from the inside out, not the outside in. Whether it’s fear, anxiety, joy, or regret—every emotional experience is rooted in top-down perceptual best guessing about the state of the body (and about the causes of this state).
we need to ask what these perceptions of the body “from within” are for. Perception of the outside world is obviously useful for guiding action, but why should our internal physiological condition be built into our conscious lives
But the goal for System B is not to figure out “what’s there”—in this case the ambient temperature. The goal is to regulate this inferred hidden cause, to take action so as to keep the temperature within a comfortable range, and ideally at a single fixed value. Perception, in this context, is not for figuring out what’s there, it’s for control and regulation.
Active inference tells us that predictive perception can be geared either toward inferring features of the world (or the body) or toward regulating these features—it can be about finding out things or about controlling things.
