Who was Richard Gregory?

A pioneering British neuropsychologist

Richard Gregory

Imagine you are walking down a foggy street, and you catch a glimpse of something in the mist. A shape. It could be a person. Or a signpost. Or maybe a shadow. You squint, adjust your focus, and suddenly—click—it resolves into a figure.

That click? That’s your brain settling on a hypothesis.

Richard Gregory, the British neuropsychologist, believed that perception isn’t a passive process. It’s not the eye simply taking in raw data and transmitting it to the brain. Instead, perception is active. It’s inferential. Interpretive. A kind of visual guesswork.

In short: we don’t just see—we interpret what we see.

The Brain as a Scientist

Gregory (1923–2010) was a professor at the University of Bristol and a pioneer in cognitive science, artificial intelligence, and visual perception. His core idea was that the brain works like a scientist formulating theories. Faced with ambiguous, incomplete, or noisy sensory input, it generates hypotheses about what’s out there, tests them against incoming data, and settles on the most plausible explanation.

He put it simply: “Perception is not determined simply by the stimulus pattern; rather it is a hypothesis, based on past experience and stored information.”

When you recognize a face, read messy handwriting, or “see” a cube in a line drawing, your brain is pulling from memory, context, and assumptions to fill in the blanks. Much of what you perceive is coming from you—your expectations, your learned patterns, your guesses.

Seeing Is Believing. Or Is It?

Gregory’s view flips the common assumption that vision is straightforward. It helps explain why illusions, hallucinations, and even miscommunication happen. If perception is driven by hypotheses, then errors in perception are bad guesses—or guesses made with the wrong context.

Take visual illusions, for example. Gregory was fascinated by them because they reveal the brain’s underlying assumptions. In the famous Müller-Lyer illusion (below), two lines of the same length appear different because of the arrowheads at the ends. Why? Because the brain is unconsciously interpreting the lines as parts of a three-dimensional scene—an inherited guess about the world, not a literal measure.

This also applies beyond vision. When we “read between the lines” in conversation, anticipate others’ actions, or interpret vague social cues, we are engaging in the same kind of hypothesis-driven processing. It’s no wonder we sometimes get it wrong.

The Personal and the Political

Gregory’s ideas have implications far beyond psychology. If our perceptions are driven by experience and learned expectations, then they are shaped by culture, media, language, and bias.

Two people can look at the same protest, the same politician, the same historical event—and see two different things. Not because they have different facts, but because they’re running different mental models.

In an era of misinformation, deepfakes, and polarized narratives, Gregory’s theory feels especially relevant. We don’t just see the world—we interpret it, often through the lens of what we already believe.

Perception as a Creative Act

Gregory didn’t see perception as a flawed system. He saw it as a brilliant solution to a hard problem. The sensory data we receive is messy, incomplete, and ambiguous. The brain’s trick is to turn that chaos into a stable world we can act in. It guesses. It predicts. And most of the time, it gets it right.

But knowing that we’re guessing machines must also give us humility. What we take as “reality” is often just a best-fit explanation. In recognizing that we must make room for curiosity, flexibility, and the ability to revise our perceptions when new information comes in.