  Although mobile phones incorporate low-cost vibration motors to enhance
touch-based interactions, it is not possible to generate complex tactile
effects on their touchscreens. It is also difficult to relate the limited
vibrotactile feedback generated by these motors to different types of physical
buttons. In this study, we focus on creating vibrotactile feedback on a
touchscreen that simulates the feeling of physical buttons using piezo
actuators attached to it. We first recorded and analyzed the force,
acceleration, and voltage data from twelve participants interacting with three
different physical buttons: latch, toggle, and push buttons. Then, a
button-specific vibrotactile stimulus was generated for each button based on
the recorded data. Finally, we conducted a threealternative forced choice
(3AFC) experiment with twenty participants to explore whether the resultant
stimulus is distinct and realistic. In our experiment, participants were able
to match the three digital buttons with their physical counterparts with a
success rate of 83%. In addition, we harvested seven adjective pairs from the
participants expressing their perceptual feeling of pressing the physical
buttons. All twenty participants rated the degree of their subjective feelings
associated with each adjective for all the physical and digital buttons
investigated in this study. Our statistical analysis showed that there exist at
least three adjective pairs for which participants have rated two out of three
digital buttons similar to their physical counterparts.
