  The emergence of mobile eye trackers embedded in next generation smartphones
or VR displays will make it possible to trace not only what objects we look at
but also the level of attention in a given situation. Exploring whether we can
quantify the engagement of a user interacting with a laptop, we apply mobile
eye tracking in an in-depth study over 2 weeks with nearly 10.000 observations
to assess pupil size changes, related to attentional aspects of alertness,
orientation and conflict resolution. Visually presenting conflicting cues and
targets we hypothesize that it's feasible to measure the allocated effort when
responding to confusing stimuli. Although such experiments are normally carried
out in a lab, we are able to differentiate between sustained alertness and
complex decision making even with low cost eye tracking "in the wild". From a
quantified self perspective of individual behavioral adaptation, the
correlations between the pupil size and the task dependent reaction time and
error rates may longer term provide a foundation for modifying smartphone
content and interaction to the users perceived level of attention.
