James Gibson (1966, 1979) argued that perception is direct — the visual world contains enough information for us to perceive it accurately without needing to infer or interpret. His view is the strongest bottom-up account of perception.
Optic flow
When you move through a scene (walking, driving, flying), patterns in the optic array sweep past your retina. Optic flow is the lawful pattern of motion across the visual field — slow at the centre of expansion (where you're heading), faster at the edges. Pilots and drivers use optic flow to control speed and trajectory; it provides direct, unambiguous information about heading.
Motion parallax
When you move sideways, closer objects sweep across the visual field faster than distant ones (a fence post rushes past while a far hill barely moves). This relative motion is a powerful cue to depth that does not require inference — it is a direct property of the moving observer's optic array.
Texture gradient
The density of texture details (pebbles on a beach, grass blades on a lawn) changes with distance: fine and dense at the horizon, coarse and sparse close up. This gradient is a continuous, direct signal of depth.
Affordances
Gibson also argued that we perceive an object's affordances — what we can do with it — directly. A chair affords sitting; a handle affords grasping; a step affords climbing. We do not first identify the object and then deduce its uses; the use is part of what we perceive.
Strengths
- Explains perception in rich, dynamic, real-world environments like driving and sports — situations where Gregory's slower top-down inference would be too slow.
- Has high ecological validity: Gibson studied military pilots in real conditions.
- Backed by evidence that very young infants react appropriately to looming objects (the visual cliff study, Gibson & Walk, 1960).
Weaknesses
- Can't easily explain visual illusions (Müller–Lyer, Ames room) — if perception is direct, why do we get them wrong?
- Can't explain ambiguous figures like the Necker cube, where the same input produces two perceptions.
- Underestimates the role of prior knowledge in everyday perception.
- Affordances are hard to test scientifically — the concept is criticised as vague.
Quick contrast
| Gibson | Gregory | |
|---|---|---|
| Direction | Bottom-up | Top-down |
| Source of meaning | Optic array (the world) | Brain (inference, schema) |
| Strong on | Real-world dynamic scenes | Static, ambiguous scenes; illusions |
| Weak on | Illusions | Speed, real-time tasks |
A balanced GCSE answer accepts that perception is mostly direct in clear conditions but uses top-down inference to fill gaps when input is ambiguous.
AI-generated · claude-opus-4-7 · v3-deep-psychology