Northwestern and Carnegie Mellon University researchers now report a fascinating discovery that provides insight into how the brain makes sense of data from fingers.
In a study of people drawing their fingers over a flat surface that has two “virtual bumps,” the research team is the first to find that, under certain circumstances, the subjects feel only one bump when there really are two. Better yet, the researchers can explain why the brain comes to this conclusion.
Their new mathematical model and experimental results on “haptic illusions” could one day lead to flat-screen displays featuring active touch-back technology, such as making your touchscreen’s keyboard actually feel like a keyboard. Tactile information also could benefit the blind, users of dashboard technology in cars, players of video games and more.
“Touch is so important in our real world, but it is neglected in the digital world,” said J. Edward Colgate, an expert in touch-based (haptic) systems. He is the Allen and Johnnie Breed University Professor of Design at Northwestern’s McCormick School of Engineering and Applied Science. “We want to create something that will make touch a reality for people interacting with their screens, and this work is a step in that direction.”
Forces felt by the fingers as they travel along a flat surface can lead to the illusion that the surface actually contains bumps. This so-called “virtual bump illusion” is well known in the haptics field, Colgate said, and the researchers were able to make use of it.
“By leveraging the virtual bump illusion, we were able to design a meaningful experiment that shed light on the way the brain integrates information from multiple fingers,” Colgate said. “Our big finding was ‘collapse' — the idea that separate bumps felt in separate fingers are nonetheless experienced as one bump if their separation happens to match that of the fingers.”
The study was published by the Proceedings of the National Academy of Sciences (PNAS).
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