120,626,225 targets. This equals 314
touch events per pixel on a state-of-the-art screen with a resolution
of 480 x 800 pixels. The amount
of data enabled us to show how
touch positions are systematically
skewed. On the basis of this data,
we derived a function that shifts
the users’ input as compensation.
We evaluated the compensation
function by publishing it as part of
an update of the game and collecting data from an additional 12,201
players. The results show that the
compensation function significantly
reduces the error rate.
The approach enabled findings
that can hardly be derived from
traditional studies. When examining
target selection on touchscreens, the
results are affected by noise, even
when using homogeneous samples
and controlled lab environments.
Facing a large number of confounding factors, we discovered, for example, that introducing a compensation
function has only a small effect.
But even an improvement of just a
few percentage points becomes relevant if the task is as pervasive as
selecting targets on touchscreens.
However, a large sample is needed
to verify this effect. The largest
amount of target-selection trials
ever collected enabled us to describe
the users’ behavior very precisely.
The amount of data enabled us to
analyze the user behavior for all
screen locations and a large variety of target sizes. In contrast to
related studies, our dataset spans
more than a hundred different
smartphone models. Each additional
factor that one considers, such as
targets with different shapes and
colors or different user groups,
• In our field experiments, we have shown that
navigation instructions encoded in vibration
patterns can significantly reduce distraction
and allow people to focus on the environment.