Rich Tactile Output on Mobile Devices

In this paper we assess the potential of rich tactile notifications on mobile phones. Many mobile phone users use vibration output for various types of notification on their phone. Currently, tactile output in phones is limited to one single actuator that can potentially present patterns based on different vibration intensity over time. To explore the possible design space, we conducted experiments with up to 6 actuators included in a phone prototype to find out about the user experience that can be created with multi-vibration output in a handheld device. The dimensions of the resulting design space are comprised of the location of the active actuators, the intensity of the vibration, and the variation of these parameters over time. Based on several user studies and interviews, we suggest design guidelines for rich tactile output facilitated by several distinct actuators. We show where vibration motors should optimally be placed and that different information can be reliably communicated by producing different patterns of vibration output using a small number of actuators.