The neuroscience of making sense

The neuroscience of making sense

Asif Ghazanfar writes:

Picture someone washing their hands. The water running down the drain is a deep red. How you interpret this scene depends on its setting, and your history. If the person is in a gas station bathroom, and you just saw the latest true-crime series, these are the ablutions of a serial killer. If the person is at a kitchen sink, then perhaps they cut themselves while preparing a meal. If the person is in an art studio, you might find resonance with the struggle to get paint off your hands. If you are naive to crime story tropes, cooking or painting, you would have a different interpretation. If you are present, watching someone wash deep red off their hands into a sink, your response depends on even more variables.

How we act in the world is also specific to our species; we all live in an ‘umwelt’, or self-centred world, in the words of the philosopher-biologist Jakob von Uexküll (1864-1944). It’s not as simple as just taking in all the sensory information and then making a decision. First, our particular eyes, ears, nose, tongue and skin already filter what we can see, hear, smell, taste and feel. We don’t take in everything. We don’t see ultraviolet light like a bird, we don’t hear infrasound like elephants and baleen whales do. Second, the size and shape of our bodies determine what possible actions we can take. Parkour athletes – those who run, vault, climb and jump in complex urban environments – are remarkable in their skills and daring, but sustain injuries that a cat doing the exact same thing would not. Every animal comes with a unique bag of tricks to exploit their environment; these tricks are also limitations under different conditions. Third, the world, our environment, changes. Seasons change, what animals can eat therefore also changes. If it’s the rainy season, grass will be abundant. The amount of grass determines who is around to eat it and therefore who is around to eat the grass-eaters. Ultimately, the challenge for each of us animals is how to act in this unstable world that we do not fully apprehend with our senses and our body’s limited degrees of freedom.

There is a fourth constraint, one that isn’t typically recognised. Most of the time, our intuition tells us that what we are seeing (or hearing or feeling) is an accurate representation of what is out there, and that anyone else would see (or hear or feel) it the same way. But we all know that’s not true and yet are continually surprised by it. It is even more fundamental than that: you know that seemingly basic sensory information that we are able to take in with our eyes and ears? It’s inaccurate. [Continue reading…]

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