01 Mar Notes on Emergent Paradigms Part III: The Predictive Mind Hypothesis
This this post was originally posted here
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This series is about “Emergent Paradigms,” and so far, we’ve looked at themes in metabolic psychiatry, the gut-brain axis, and a contemplative renaissance in the West.
Today, we’re taking a brief look at an emergent paradigm in the cognitive sciences that has been building for several decades, that goes by the Predictive Mind Hypothesis.
This essay is just a starting point for non-technical laypeople (normies) like me who want to go deeper into a very technical topic—perhaps the most technical topic there is: the science of the human brain, mind, and conscious awareness.
If you’re reading this newsletter, you likely have an interest in psychedelics and related matters, and our topic today is about understanding the intimate relationship between brain, body, and environment and, thus, has massive implications for well-being, mental and emotional illness, meditation and, of course, psychedelics.
The Predictive Mind Hypothesis contends that perception is fundamentally a matter of prediction.
In this view, the brain continuously generates predictions about incoming sensory information and—crucially—projects these predictions into our conscious awareness as perception.
In other words, what we see, hear, smell, taste, and feel (sensations and emotions) are predictions about the world generated by the brain—not the sensory stimuli itself.
Let’s explore this a bit.
The most common understanding we lay people have is that perceptions and experience are the result of our sense organs (eyes, ears, etc.) sensing stimuli from the environment (sound waves, light rays, etc.) and projecting them into the associated parts of the brain (visual cortex, auditory cortex, etc.) and from which we experience these senses in conscious awareness like a movie projected onto the screen of the mind.
In other words, the brain is a passive receiver and projector of incoming sensory information.
This conceptualization is often depicted in images like this:
In this rendering, our eyes are like movie cameras, our ears are like microphones, and our other sense organs passively receive incoming information as our brain processes and projects it to our conscious awareness.
In scientific parlance, this outdated understanding is referred to as Bottom-up processing.
According to this model, perception begins with the stimulus itself, and processing is carried out in a linear, ascending manner, where simple sensory details are integrated into more complex interpretations as information moves from lower to higher levels of processing.
However, the Predictive Mind Hypothesis—turns this concept on its head and claims that our conscious experience—what we see, hear, feel, etc.—is not necessarily an accurate representation of the environment as it is but rather a prediction about the sensory information based on a model of the world that we have built from past experiences.
In other words, this hypothesis suggests that perception and our sensory experience are the brain’s best guesses (predictions) about the sensory inputs it expects to receive from the environment.
Neuroscientist and author Anil Seth put it this way in his TED talk titled “Your brain hallucinates your conscious reality.”
“Perception right here, right now, is not a window onto the world but more like a controlled hallucination, where what we hear, what we see, what we feel, are all an internal simulation, a kind of best guess of what’s out there in the world, generated by our brains.”
A conceptual rending of this inversion might look like this:
The Predictive Mind Hypothesis posits the brain is constantly generating and updating a mental model (often called a Generative Model) of one’s body, the space around it, internal and external stimuli, and their causes.
As the picture above (thanks, ChatGPT) suggests, experience is the brain’s predictive model of the world, not the world itself.
Rather than directly rendering sensory stimuli from the environment, the brain uses incoming sensory information to correct its predictions.
Karl Friston, a computational Neuroscientist and the world’s authority on this topic, notes:
“In this view, the brain is an inference machine that actively predicts and explains its sensations. Central to this hypothesis is a probabilistic model that can generate predictions, against which sensory samples are tested to update beliefs about their causes.”
Why would this be the case?
Why would evolution select for brains that project predictions into conscious awareness rather than render what is actually happening? Because the energy and computational power required to receive, process, and render sensory information in real time are so great that it is physically impossible.
As noted above, this is just a starting point. The take-home message is that what you and I perceive and respond to is fabricated by our brains.
Importantly, the Predictive Mind Hypothesis may end up providing a unifying framework to understand things like depression, meditation, and psychedelics.
Depression can be seen as a state where the brain’s predictive models become maladaptively rigid. Meditation offers a practice to consciously recalibrate and soften these models, enhancing mental flexibility and well-being. Psychedelics, meanwhile, offer a radical means of temporarily resetting the brain’s predictive machinery, potentially freeing individuals from deeply ingrained patterns of thought and perception.
Depression, when viewed through the Predictive Mind Hypothesis, can be understood as a disorder of prediction.
Essentially, the brain’s predictive models become rigid and negatively biased, leading to a perpetual expectation of negative outcomes or interpretations of sensory inputs.
This bias skews perception, emotion, and thought patterns towards the negative, and the generative model becomes less flexible, making it harder to update beliefs in light of new, positive experiences.
Thus, depression might be seen not just as a chemical imbalance but as a maladaptive predictive processing pattern where the brain struggles to adjust its internal models in response to the external world.
Meditation practices can be framed as techniques for becoming aware of and recalibrating the brain’s predictive models.
By fostering an attitude of open awareness and non-judgmental observation, meditation encourages the brain to become more flexible in its predictions.
Practitioners learn to observe thoughts, feelings, and sensations as transient phenomena, reducing their impact on the brain’s predictive models.
This can lead to a more accurate appraisal of sensory inputs and a reduction in the over-interpretation of negative stimuli.
Meditation, therefore, enhances the brain’s ability to update its predictions in a more balanced and less biased manner, promoting mental well-being and resilience.
Psychedelics, in a predictive framework, can be thought of as temporarily disrupting the brain’s predictive engine. That is, the predictive model of ourselves, our surroundings, and the world is broken down, and thus, the filter of sensory experience is removed.
By disrupting the brain’s predictive filters, psychedelics can heighten the intensity of sensory and emotional experiences. Normally, the brain’s predictions serve to dampen the impact of incoming sensory information based on past experience.
Under the influence of psychedelics, this dampening effect is reduced, leading to a more raw and unfiltered experience of the world. This can result in vivid visual hallucinations, enhanced emotional responses, and a sense of awe or wonder as the brain processes sensory information in a less predictable and more novel way.
Importantly for their therapeutic application, this process may facilitate memory reconsolidation, wherein existing memories are recalled and potentially modified before being stored again.
By creating a flexible and receptive state of mind, psychedelics may help individuals to reevaluate and change deeply ingrained patterns of thought and behavior that allow for the updating of maladaptive predictive models related to trauma or negative beliefs about oneself.
By understanding these phenomena through the lens of the Predictive Mind Hypothesis, I think we will gain insights into the mechanisms underlying mental health and consciousness itself.
This perspective will continue to inform our scientific, therapeutic, and cultural landscape in profound ways, especially as technology progresses, creating a new paradigm of the mind and the brain.
What a time to be alive.
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