The Ego Tunnel: The Science of the Mind and the Myth of the Self

by Thomas Metzinger

PART TWO IDEAS AND DISCOVERIES

THREE OUT OF THE BODY AND INTO THE MIND Body Image, Out-of-Body Experiences, and the Virtual Self

“Owning” your body, its sensations, and its various parts is fundamental to the feeling of being someone. Your body image is surprisingly flexible. Expert skiers, for example, can extend their consciously experienced body image to the tips of their skis.

Race-car drivers can expand it to include the boundaries of the car; they do not have to judge visually whether they can squeeze through a narrow opening or avoid an obstacle—they simply feel it.

All these are examples of what philosophers call the sense of ownership, which is a specific aspect of conscious experience—a form of automatic self-attribution that integrates a certain kind of conscious content into what is experienced as one’s self.

Neuroimaging studies have given us a good first idea of what happens in the brain when the sense of ownership, as illustrated by the rubber-hand experiment discussed in the Introduction, is transferred from a subject’s real arm to the rubber hand: Figure 2 shows areas of increased activity in the premotor cortex.

It is plausible to assume that at the moment you consciously experience the rubber hand as part of your body, a fusion of the tactile and visual receptive fields takes place and is reflected b...

Figure 2: The rubber-hand...

Your bodily self-model is created by a process of multisensory integration, based on a simple statistical correlation your brain has discovered.

The phenomenal incorporation of the rubber hand into your self-model results from correlated tactile and visual inputs.

As the brain detects the synchronicity underlying this correlation, it automatically forms a n...

The beauty of the rubber-hand illusion is that you can try it at home. It clearly shows that the consciously experienced sense of ownership is directly determined by representational processes in the brain.

Recently, psychometric studies have shown that the feeling of having a body is made up of various subcomponents—the three most important being ownership, agency, and location—which can be dissociated.

“Me-ness” cannot be reduced to “here-ness,” and, more important, agency (that is, the performance of an action) and ownership are distinct, identifiable, and separable aspects of subjective experience.

Gut feelings (“interoceptive body perception”) and background emotions are another important cluster anchoring the conscious self,4 but it is becoming obvious that ownership is close...

Phenomenal ownership is not only at the heart of conscious self-experience; it also has unconscious precursors. Classical neurology hypothesized about a body schema, an unconscious but constantly updated brain map of limb positions, body shape, and posture.6 Recent research shows that Japanese macaques can be trained to use tools even though they only rarely exhibit tool use in their natural environment.

During successful tool use, changes occur in specific neural networks in their brains, a finding suggesting that the tools are temporarily integrated into their body schemata.

When a food pellet is dispensed beyond their reach and they use a rake to bring it closer, a change is observed in the...

Recent neuroscientific data indicate that any successful extension of behavioral space is mirrored in the neural substrate of the body image in the brain.

One can plausibly assume that some of the elementary building blocks of human tool-use abilities existed in the brains of our ancestors, 25 million years ago.

Then, due to some not-yet-understood evolutionary pressure, they exploded into what we see in humans today.

As soon as you can consciously experience a tool as integrated into your bodily self, you can also attend to this process, optimize it, form concepts about it, and control it in a more fine-grained manner—performing what today we call acts of will.

Conscious self-experience clearly is a graded phenomenon; it increases in strength as an organism becomes more and more sensitive to an internal context and expands its capacities for self-control.

Figure 3: Integrating touch...

Figure 4: Japanese macaques exhibit intelligent tool use.

Incorporation of artificial actuators into widely distributed brain regions may someday allow human patients successfully to operate advanced prostheses (which, for example, send information from touch and position sensors to a brain-implanted, multichannel recording device via a wireless link), while also enjoying a robust conscious sense of ownership of such devices.

It now looks as if even the evolution of language, culture, and abstract thought might have been a process of “exaptation,” of using our body maps for new challenges and purposes—a point to which I return in the chapter on empathy and mirror neurons.

Put simply, exaptation is a shift of function for a certain trait in the process of evolution: Bird feathers are a classic example, because initially these evolved “for” temperature regulation but later were adapted for flight.

Here, the idea is that having an integrated bodily self-model was an extremely useful new trait because it made a host o...

THE OUT-OF-BODY EXPERIENCE

My own interest in consciousness arose from a variety of sources, which were mostly academic but also autobiographical. At some points, the theoretical problem appeared directly and unexpectedly in my life. As a young man, I encountered a series of disturbing experiences, of which the following is a typical instance:

Six years later, I was aware of the concept of the out-of-body experience (OBE), and when such episodes occurred, I could control at least parts of the experience and attempt to make some verifiable observations.

Figure 5: Kinematics of the phenomenal body image during OBE onset: The “classical” motion pattern according to S. Muldoon and H. Carrington, The Projection of the Astral Body (London: Rider & Co., 1929).

In some of my recent research, I have been trying to disentangle the various layers of the conscious self-model—of the Ego.