Peripheral Drift 💀 Expert
Pinna-Brelstaff Illusion
Moving your eyes around the image causes these concentric rings of tilted tiles to rotate, though it is 100% static.
Move your eyes around the image — don't stare at one point
Use the controllers inside the display card to interact with the visual triggers.
Use the controllers inside the display card to interact with the visual triggers.
🎮 EXPERIENCE IT FIRST
Before reading the neuroscience explanation below, take a moment to interact with the demo above:
- How does the visual change when you move your eyes or look at different parts of the screen?
- Use the slider or toggle buttons to reveal the actual geometric layout. Did it match what your eyes predicted?
- Pay attention to whether you can consciously force your brain to switch between interpretations.
🧠 THE SCIENCE
The Pinna-Brelstaff illusion represents a fascinating interaction between spatial geometry and motion integration. Concentric rings of small square tiles are tilted in opposite directions (the inner ring slants counter-clockwise, the outer slants clockwise). When you move your head closer to the screen or look around the image, the rings appear to rotate in opposite directions. As you move closer or further, the expansion and contraction of the image across your retina triggers radial motion signals. However, because the individual tiles are tilted, the orientation-sensitive neurons in V1 and V2 detect a directional offset. When these signals are integrated in the motion area MT/V5, the radial expansion vectors are warped by the tilt angles, converting the visual signal into a rotary vector. This forces the brain to perceive rotation where only expansion/contraction exists.
💡 FUN FACTS
- • Discovered by Baingio Pinna and Gavin Brelstaff during studies on visual orientation maps.
- • The illusion shows that our motion-sensing area MT/V5 is heavily biased by local edge orientations.
- • If you close one eye, the perceived rotation is reduced because depth-sensing pathways are suppressed.
- • The inner and outer rings rotate in opposite directions because their tiles tilt in opposite directions.
🧪 TRY THIS AT HOME
Hold your phone at arm's length and stare at the center dot. Keep staring as you bring the phone close to your face. Watch the inner and outer rings twist in opposite directions, then twist back as you pull the phone away!
📜 WHO DISCOVERED IT
Discoverer: Baingio Pinna & Gavin Brelstaff (2000)
Pinna and Brelstaff were experimenting with concentric circles made of tilted parallelogram blocks. They discovered that when observers walked toward the display, the rings appeared to spin. This led to breakthroughs in how we understand local-to-global motion integration.
Educational Resources & History
Pinna-Brelstaff optical illusion explanation. Learn how concentric rings of tilted tiles convert radial movement into illusory rotation, and explore the neurobiology of MT/V5 motion integration.