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\addsec{Abstract}

Keyboards are omnipresent in modern society. Hospitals, retail stores, offices
or at home, the keyboard is still, the main input device for almost anyone that
interacts with a computer. However, at some point, many people experience
discomfort or even pain while using a keyboard because of the many small and
repetitive movements the fingers have to do to operate it. Therefore, in this
thesis we try to evaluate an alternative, non-uniform keyboard design where each
individual \textit{mechanical} keyswitch is equipped with a spring that features
a resistance appropriate for the specific finger usually operating it. The idea
behind this adjusted design is to particularly reduce the load on weaker fingers
and still pertain or even enhance typing performance. Additionally, we try to
answer the question, whether or not a keyboard with, per finger, adjusted
actuation force has a positive impact on efficiency and overall
satisfaction. Thus, we evaluated the current availability of resistances for
mechanical keyswitches and conducted a preliminary telephone interview (n = 17)
to assess preferences, use-cases and previous experiences with
keyboards. Further, we ran another preliminary experiment, where we measured the
maximum applicable force for each finger in different positions related to
keyboarding as a basis for our adjusted keyboard design. Lastly, during a three
week laboratory user study with twenty-four participants, the adjusted keyboard
design and three traditional keyboards with 35\,g, 50\,g and 80 g actuation
force were compared to each other in terms of performance and user
satisfaction. The statistical analysis revealed, that especially error rates are
positively influenced by higher actuation forces and that keyboards with neither
too heavy nor to light resistance generally perform the best in terms of typing
speed. Further, the adjusted keyboard and the 50\,g keyboard performed almost
identically in all tests and therefore we could not derive any significant
improvements in performance or satisfaction over traditional designs that
utilize keyswitches with moderate resistance. However, we concluded, that with
the equally good results, the adjusted design is still a viable alternative and
with further improvements, e.g., complete personalization of spring resistance
for each key, could possibly enhance the user experience and performance for
sophisticated typists.










% Even though experts recommend to regularly take a break from
% keyboard work to prevent such symptoms, these recommendations can rarely be
% implemented in working environments, where productivity and tight schedules are
% very common. If the pain or discomfort persists, people have to either reduce or
% a completely stop working with a keyboard, which in some cases might even force
% them to change their profession.