Top-down processing
Also known as: Conceptually driven processing
Perception guided by knowledge and expectation, not just raw input.
What it means
Top-down processing is perception and pattern recognition driven by higher-level knowledge, context, and expectations that shape the interpretation of sensory data, as opposed to bottom-up processing that builds percepts from the raw features upward. The brain continually generates predictions about what it is likely to encounter and uses incoming signals to confirm or correct them, which makes perception fast and robust to noisy or incomplete input. The cost is susceptibility to expectation-driven errors and illusions when priors are wrong. Top-down effects explain why we can read smudged handwriting, restore missing speech sounds, and miss typos in familiar words. It is the mechanism behind perceptual set and a central idea in predictive accounts of the mind.
Examples
You effortlessly read a word with a missing letter because context predicts what it must be.
In a noisy pub you 'hear' half a sentence that never reached your ears — expectation fills the gaps, which is also why a mumbled lyric turns into confident nonsense.
A radiologist told to look for a fracture spots one faster — and is likelier to miss the unexpected finding sitting elsewhere on the same X-ray.
First described in Richard Gregory; contrasted with Gibson's bottom-up view.