In “SemFeel: A UI with semantic tactile feedback for mobile devices,” Koji Yatani and Khai N. Truong in the Department of Computer Science University of Toronto describe a tactile feedback system which informs the user about the presence of an object he or she touches on the screen and then offers additional semantic information about that item.

Through multiple vibration motors attached to the backside of a mobile touch-screen device, the SemFeel system they built can generate different patterns of vibration, indicating flow from right to left or from top to bottom to help the user in the interaction with the mobile device.They have found that users can distinguish ten different patterns, including linear and circular ones, with about 90% accuracy. interactions.