The Kanizsa triangle shows perception can run on inference without any real object

Evidence

If you are like most people, you will see an upright bright white triangle shape on top of an inverted triangle. But the triangle doesn’t actually exist. The Pac-Man-like configuration merely triggers the perception of an illusory contour. The basic process of human vision I described above starts with a chain of events initiated by an external stimulus; this is called ‘bottom-up’ cognition. But the visual cortex also receives input from other areas of the brain when we perceive something familiar (such as a triangle). This is called ‘top-down’ cognition – top-down because information travels from higher cortical structures down to the visual cortex. It’s an internal process and, as such, it is literally ‘all in your head’. — Sander van der Linden, Foolproof, 60

Categorization

• DEFINE: Pairs bottom-up and top-down cognition with the Kanizsa triangle as a concrete anchor — useful reference material later when the book draws the information-falsehood parallel.
• XREF: connects to: Human vision is probabilistic inference, not faithful recording of light — Sander van der Linden, Foolproof: Why Misinformation Infects…, 58; Perceptual unity arises from purposive traversal rather than passive observation; Perception is a brain interpretation that need not use all sensory detail — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1323 (+1 more)

Broader Connections

• Perception arrives pre-shaped by expectations and context, never raw #expands (0.85) — Sarah Bakewell, At the Existentialist Café, 729
• Perception is a brain interpretation that need not use all sensory detail #expands (0.78) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1323
• Perceptual unity arises from purposive traversal rather than passive observation #corroborates (0.72)