Perception is reality. That is the summary of the book. Seeing is active, not passive. What you decide to see determines your life. With the observer effect, you must be careful about what you see. You programme the quantum foam. The world and body we experience are always part construct: a product of our own conscious and nonconscious predictions. How we see and experience the world is routinely shaped and guided by our own predictions and expectations.
The Experience Machine
Hence, “The Experience Machine: How Our Minds Predict and Shape Reality”. It is a difficult book to explain as it goes into some deep (and fascinating) science trying to explain predictive processing. Nothing we do or experience is untouched by our own expectations. Instead, all human experience is part phantom—the product of deep-set predictions. Our brains are basically guessing machines, proactively anticipating signals from the body and the surrounding world. Human experience and thinking are orchestrated from the inside by neuronal activity and the dense network of brain-body interactions and from the outside by the highly structured social and technological worlds in which we live and act.
A lot of the experience is inside
Whereas sensory information was often considered to be the starting point of experience, the emerging science of the predictive brain suggests a rather different role. According to this new picture, experience—of the world, ourselves, and even our own bodies—is never a simple reflection of external or internal facts. Much of the experience is inside, not outside. When the brain strongly predicts a certain sight, sound, or feeling, that prediction plays a role in shaping what we seem to see, hear, or feel. Emotion, mood, and even planning are all based on predictions, too. Alter those predictions (for example, by “reframing” a situation using different words), and our experience itself alters.
Hallucinate the world
Everything that you see, hear, touch, and feel reflects hidden wells of prediction. The perceiving brain is never passively responding to the world. Instead, it is actively trying to hallucinate the world and checking that hallucination against the evidence coming in via the senses. This means that we can, at times, change how we feel by changing what we (consciously or unconsciously) predict.
Brains are nothing other than large-scale prediction machines. For example, the number of neuronal connections carrying signals backwards in this way is estimated to exceed the number of connections carrying signals forward by a very substantial margin, in some places by as much as four to one. Instead of constantly expending large amounts of energy on processing incoming sensory signals, the bulk of what the brain does is learn and maintain a kind of model of body and world—a model that can then be used, moment by moment, to try to predict the sensory signal. That explains the need for all that downward connectivity.
Making perception turn on prediction has another important benefit too. It enables the brain to process incoming sensory information in a way that is quite remarkably efficient. Compression by informed prediction saves on bandwidth by, in effect, “adding back in” all the successfully predicted elements. The system “hallucinates” the usual world, updating only when something unexpected occurs.
Systems like that are wonderfully frugal in their use of the incoming stream of information. Instead of trying to deal with everything from scratch, they effectively sift and filter the incoming data by highlighting only what was unexpected. Every time we make sense of our worlds through perceptual encounters, we do so by means of both the incoming sensory signals and a rich invisible stream of knowledge-based predictions.
Just as in the case of outward-looking sensing using eyes and ears, the brain does not passively wait for inward-looking pain information to arrive via the nerves. Instead, it proactively predicts the arrival and intensity of pain information and estimates the likely reliability of its own predictions.
- Pain can sometimes be remarkably disconnected from standard bodily causes. What we feel is, in every case, a construct.
- The same kind of thing can occur over longer periods of time and in less obvious ways, too, allowing not just pain but many other medical symptoms to be genuinely experienced despite the absence of the usual kinds of physiological cause.
- After several bouts of back pain, people start to process the world differently. Their pain becomes embedded among the things they associate with themselves.
Perception is active
Perception is no longer a passive phenomenon. Instead, perception and action constantly engage in a kind of coupled unfolding—movements serve up perceptions that enable more motor movements that deliver further perceptions. Vision itself, this body of work suggests, is a highly active and intelligent process.
Perception is full-body
Every thought, memory, emotion, or perception you construct in your life includes something about the state of your body. Every prediction you make, and every categorization your brain completes is always in relation to the activity of your heart and lungs, your metabolism, your immune function, and the other systems that contribute to your body budget. What an emotion really is, is the self-perception of changes in our own bodily states.
It is the primary task of all the prediction machinery in our heads to help us stay alive. That means acting and responding in ways that help create and maintain the many inner physiological states essential to our continued existence as a living organism. Just as a financial budget tracks income and expenditure, a body budget tracks and anticipates the use and replenishment of key resources for maintaining bodily life and functioning.
If we feel thirsty, we may take a drink of water. We immediately feel less thirsty, even though it will actually take the water around twenty minutes to reach the bloodstream and deliver the required effects. In other words, both the feeling of thirst and the feeling of having quenched your thirst each reflect anticipatory processing. Other examples:
- We do not wait until we are actually out of fuel (sugar, water) before taking remedial action. Instead, we model ourselves well enough to step in in good time.
- Motor control poses a similar challenge. Due to limitations in the speed of transmission of signals along nerve fibres, real sensory feedback often arrives far too late to be of much use in guiding action.
Emotions are perception
Feelings and emotions are what result when we integrate basic information about bodily states and general arousal with higher-level predictions of their most probable causes—for example, heart attack versus exercise. As your bodily state alters, the salience of various worldly opportunities (to eat, for example) alters, too. That means you will also act differently, harvesting different streams of information. We can now think of sentient beings as those whose neural model of the world is in constant two-way communication with a model of their own changing physiological state. They will respond to their worlds in ways informed by a delicate dance between what they detect in the external world and their own ever-changing bodily needs and states. This is what underlies all the behavioural manifestations of “sentience.”
One of the functions of the biological brain is to create and maintain perception-action loops that keep us alive and bring us closer to our goals. We humans are, and long have been, “natural-born cyborgs.” We use technology to improve the information stream available to the brain or by altering the problem space itself. For example, when you google movie times, you are probably unaware that you are resolving ambiguities about the future, acting to minimize errors that would otherwise occur. The chips in your mobile and your computers are now part of the material underpinnings of your mind. The chip has a trusted nonbiological structure that is delicately and constantly coupled to the rest of the system that we recognize as “you.” The brain couples technology with our affective response circuitry, too. That functionality is now simply taken for granted by the predictive brain. Many of our daily devices, especially our smartphones and other wearables, are already starting to act as woven resources. They are devices whose constant functionality has become factored deep into our brain’s ongoing estimations of what kinds of operation can be performed and when.
Your personalized AIs will come online when you are very young. They would learn from your choices and contribute to your choices in turn. Living, working, and playing in these enriched settings, we will continue the humanity-defining process of blurring the already fuzzy boundaries between self and nonself, mind and tool, person and world.
Instead, true mental circuitry could indeed be spread out across the brain, body, and aspects of the material and technological world. Minds are not merely what brains do. They are what brains create—distributed cognitive engines spanning the brain, body, and world. Our current view is that the true core of the extended mind thesis lies precisely there, in the claim that the boundaries of perception and action need not mark hard-and-fast boundaries of the “mind.”
We can learn to “expect better.” And we must.
- Placebo-induced changes have been shown to reach far down, altering responses even at the level of the spinal cord. The higher the patient’s estimate of the power of the intervention, the greater its effect.
- Hypnosis can produce similar effects and is sometimes so effective that some people can comfortably undergo invasive surgery under its influence.
- By retraining our unconscious prediction machinery, fictional worlds can also act as powerful tools for pushing back here. Immersive virtual reality provides what could prove to be the most potent of all such interventions. For example, patients suffering pain from burns get subjective relief using a winter-scene VR program called Snow-World, similar to that obtained by using intravenous opioids.
- Improving interoception is achieved by using simple wearable devices to deliver ongoing biofeedback information.
Training your placebo
Understanding the normal functioning of the predictive brain paves the way for an evidence-led approach that recognizes both the power and limitations of such effects. You can train“phenomenological control”—the capacity to exert a kind of control over the shape of your own experience. The techniques are self-affirmation, reframing, psychedelics, meditation and controlling attention.
You are what you think
We are what predictive brains build. If predictive processing lives up to its promise as a unifying picture of the mind and its place in nature, we must think about ourselves, our worlds, and our actions in new ways. This should be the start of a slow but important process eroding the old distinctions between psychiatry, neurology, and computational neuroscience and finally embracing the fundamental unity of mind, body, and world.
Brain structure and neurochemistry, the physiological body, our own actions, history, and practices, and the environmental settings in which we live and work all combine and cooperate to manage the flow of prediction. We should be careful what kinds of material, digital, and social worlds we build because in building those worlds, we are building our minds, too.