NEW YORK: What if the touchscreen of your smartphone or tablet could touch you back? It does happen, researchers report.

In a study of people drawing their fingers over a flat surface that has two "virtual bumps", the team from Northwestern University and Carnegie Mellon University found that, under certain circumstances, the subjects feel only one bump when there really are two.

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.

Touch is so important in our real world, but it is neglected in the digital world.

"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," said J Edward Colgate, an expert in touch-based (haptic) systems from Northwestern's McCormick School of Engineering and Applied Science.

The team's experiment presented two "virtual bumps" to subjects participating in the study. When bump and finger spacing were identical, subjects reported feeling two bumps as one.

In this case, the brain thinks it is too coincidental that there should be two bumps at the same time so it registers the bumps as one. The new model 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. The findings also provide insight into how the brain makes sense of data from fingers.