*Reality is constructed by the brain, and no two brains are exactly alike*
By Anil K. Seth (@anilkseth) | Scientific American September 2019 Issue
https://www.scientificamerican.com/article/the-neuroscience-of-reality/
...
The central idea here is that perception is a process of active
interpretation geared toward adaptive interaction with the world through
the body rather than a recreation of the world within the mind. The
contents of our perceptual worlds are controlled hallucinations,
brain-based best guesses about the ultimately unknowable causes of sensory
signals. And for most of us, most of the time, these controlled
hallucinations are experienced as real. As Canadian rapper and science
communicator Baba Brinkman suggested to me, when we agree about our
hallucinations, maybe that is what we call reality.
But we do not always agree, and we do not always experience things as real.
People with dissociative psychiatric conditions such as derealization or
depersonalization syndrome report that their perceptual worlds, even their
own selves, lack a sense of reality. Some varieties of hallucination,
various psychedelic hallucinations among them, combine a sense of unreality
with perceptual vividness, as does lucid dreaming. People with synesthesia
consistently have additional sensory experiences, such as perceiving colors
when viewing black letters, which they recognize as not real. Even with
normal perception, if you look directly at the sun you will experience the
subsequent retinal afterimage as not being real. There are many such ways
in which we experience our perceptions as not fully real.
What this means to me is that the property of realness that attends most of
our perceptions should not be taken for granted. It is another aspect of
the way our brain settles on its Bayesian best guesses about its sensory
causes. One might therefore ask what purpose it serves. Perhaps the answer
is that a perceptual best guess that includes the property of being real is
usually more fit for purpose—that is, better able to guide behavior—than
one that does not. We will behave more appropriately with respect to a
coffee cup, an approaching bus or our partner’s mental state when we
experience it as really existing.
But there is a trade-off. As illustrated by the dress illusion, when we
experience things as being real, we are less able to appreciate that our
perceptual worlds may differ from those of others. (The leading explanation
for the differing perceptions of the garment holds that people who spend
most of their waking hours in daylight see it as white and gold; night
owls, who are mainly exposed to artificial light, see it as blue and
black.) And even if these differences start out small, they can become
entrenched and reinforced as we proceed to harvest information differently,
selecting sensory data that are best aligned with our individual emerging
models of the world, and then updating our perceptual models based on these
biased data. We are all familiar with this process from the echo chambers
of social media and the newspapers we choose to read. I am suggesting that
the same principles apply also at a deeper level, underneath our
sociopolitical beliefs, right down to the fabric of our perceptual
realities. They may even apply to our perception of being a self—the
experience of being me or of being you—because the experience of being a
self is itself a perception.
This is why understanding the constructive, creative mechanisms of
perception has an unexpected social relevance. Perhaps once we can better
appreciate the diversity of experienced realities scattered among the
billions of perceiving brains on this planet, we will find new platforms on
which to build a shared understanding and a better future—whether between
sides in a civil war, followers of different political parties, or two
people sharing a house and faced with washing the dishes.
@philipthrift
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