  To increase mobile user engagement, current apps employ a variety of
behavioral nudges, but these engagement techniques are applied in a
one-size-fits-all approach. Yet the very same techniques may be perceived
differently by different individuals. To test this, we developed HarrySpotter,
a location-based AR app that embedded six engagement techniques. We deployed it
in a 2-week study involving 29 users who also took the Big-Five personality
test. Preferences for specific engagement techniques are not only descriptive
but also predictive of personality traits. The Adj. $R^2$ ranges from 0.16 for
conscientious users (encouraged by competition) to 0.32 for neurotic users
(self-centered and focused on their own achievements), and even up to 0.61 for
extroverts (motivated by both exploration of objects and places). These
findings suggest that these techniques need to be personalized in the future.
