  The effectiveness of digital treatments can be measured by requiring patients
to self-report their state through applications, however, it can be
overwhelming and causes disengagement. We conduct a study to explore the impact
of gamification on self-reporting. Our approach involves the creation of a
system to assess cognitive load (CL) through the analysis of
photoplethysmography (PPG) signals. The data from 11 participants is utilized
to train a machine learning model to detect CL. Subsequently, we create two
versions of surveys: a gamified and a traditional one. We estimate the CL
experienced by other participants (13) while completing surveys. We find that
CL detector performance can be enhanced via pre-training on stress detection
tasks. For 10 out of 13 participants, a personalized CL detector can achieve an
F1 score above 0.7. We find no difference between the gamified and non-gamified
surveys in terms of CL but participants prefer the gamified version.
