By ChatGPT
This explainer is written to accompany and clarify Martin Jambon’s short note: There’s no correct perception (original note).
Most people assume that perception is a window onto the world—that our senses report what is “really there,” and that our brains faithfully reconstruct the truth from this incoming data. This assumption is natural because perception feels immediate and reliable. We open our eyes and simply see the world.
But perception does not work that way.
A more accurate picture, supported by modern neuroscience, evolutionary reasoning, and everyday experience, is this:
There is no universally correct perception—only perception that is useful for action.
Perception is not a mirror of reality. It is a continuously updated model constructed by a particular mind for the practical purpose of guiding that mind’s body through its environment. Below, we unpack what this means and why it matters.
When light strikes the retina or sound enters the ear, the brain does not simply “decode” this input into a perfect representation. Sensory signals are incomplete, ambiguous, and often extremely noisy. They require interpretation.
A brain has to answer questions like:
These are inference problems, not decoding problems.
The brain must guess. It must combine:
The “world” we perceive is the result of this ongoing interpretation.
Every brain brings its own priors—its internal “starting points”—to the act of perception. These come from multiple sources:
Genetics Brains differ in wiring, sensitivity, attentional style, and tendencies toward pattern detection.
Culture and personal history Languages, technologies, habits, and learned distinctions create perceptual categories.
Current state of mind Fearful people perceive threats more readily; joyful people perceive opportunities.
Health and alertness Exhaustion, illness, and injury distort perception by altering attention and sensory weighting.
Psychoactive drugs These adjust the balance between imagination and sensory input, sometimes dramatically.
These factors don’t just color our perception—they constitute it. Two people standing side by side may literally perceive different worlds.
A useful metaphor from cognitive science is that the brain is constantly predicting what the world is like, and sensory input is used to correct its predictions. This leads to the striking but accurate idea:
Perception = imagination, guided by sensory evidence.
This does not mean perception is unreal. It means the brain constructs the most plausible explanation for the data it receives, given its aims and limitations.
When you recognize a friend’s face instantly, you are not decoding every pixel—you are matching signals to an existing model.
When you mishear a word in a noisy room but “correct” it once context becomes clear, your expectations have reshaped the input.
Imagination is not the opposite of perception; imagination powers perception.
Because perception is the interaction between top-down (imagination, expectations) and bottom-up (sensory evidence), problems arise when either side dominates.
If the brain relies almost entirely on raw sensory data:
This can occur in certain neurological conditions or during extreme sensory overload.
If top-down predictions overwhelm sensory evidence:
This can happen with sleep deprivation, psychosis, strong emotions, or certain drugs.
The purpose of perception is not truth but navigation. Perception succeeds when it helps the organism:
Accuracy matters only insofar as it supports these outcomes. A perfectly “true” representation that leads to paralysis or confusion would be evolutionarily useless.
If organisms perceived reality exactly as it is—down to every wavelength, vibration, and distribution of particles—the result would be computational overload.
What evolution selects for is not truth but fitness, meaning:
We see only the slices of the world that matter for action.
Color categories, object boundaries, melodic intervals, social cues—all are useful simplifications.
Most likely, yes. But our perceptual systems do not aim to reveal it directly. They aim to construct functional models that allow us to act effectively within whatever the underlying reality is.
In this sense, perception is similar to scientific modeling:
There is no single correct perception, only perceptions that work.
Understanding the constructive nature of perception helps explain:
It also encourages humility: our view of the world is always one possible interpretation among many.
At the evolutionary and cognitive levels, perception is judged not by its objective accuracy but by its effects:
Does this perception help the organism act in ways that support its continued existence?
When perception fails—whether through overload, hallucination, trauma, or simply poor inference—the consequences show up as maladaptive action: missed opportunities, dangers not avoided, needs not met.
This functional criterion is why useful perception matters more than correct perception.
Perception is the mind’s ongoing attempt to make sense of the world with the tools available—its biology, its history, its culture, its expectations, and its moment-to-moment state.
What we perceive is not the world “as it is,” but the world as it matters.
This explainer was written by ChatGPT to accompany Martin Jambon’s original note.