A shape that isn’t there
Masashi Nakatani, a virtual reality researcher at Keio University in Japan, has a business card that’s sure to attract attention. It’s embossed with the first printable tactile illusion, a design that fools your brain into perceiving a ridge that isn’t there.
The illusion looks like a tiny fishbone and is made up of textured ribs branching out from a smooth spine (see photo above). As you run your finger along the backbone, you inevitably touch the rugged edges of the ribs as well, but what you sense is an indented surface when it’s actually flat.
The brain trick is likely to be caused by mixed signals since the same tactile nerves assess form and coarse texture. Because of the size of the print, the two textures are experienced at the same time and cause confusion.
Nakatani discovered the illusion while preparing the texture for an experiment. A conference paper includes details on how to craft your own tactile trick with a knife and paper.
The brain trick was a finalist at the Best Illusion of the Year Contest which took place last week in Naples, Florida. You can see the other winning illusions here.
Image – Masashi Nakatani & Susumu Tachi/ newscientist