The muscles surrounding the human eye are capable of performing a wide range of expressions such as squinting, blinking, frowning, and raising eyebrows.
This work explores the use of these ocular expressions to expand the input vocabularies of hands-free interactions.
We conducted a series of user studies:
1) to understand which eye expressions users could consistently perform among all possible expressions,
2) to explore how these expressions can be used for hands-free interactions through a user-defined design process, and
3) to collect user feedback on these interactions.
Our study results showed that most participants could consistently perform 9 of the 18 possible eye expressions. Also, in public settings, participants preferred eye expressions over hand gestures for most of the interactions used by the state-of-the-art augmented reality (AR) head-mounted displays.