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32
abstractEN.tex
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@ -6,22 +6,22 @@ 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 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 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 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 thesis we try to evaluate an alternative, non-uniform keyboard design where each
each individual \textit{mechanical} keyswitch is equipped with a spring, that individual \textit{mechanical} keyswitch is equipped with a spring that features
features a resistance, appropriate for the specific finger usually operating a resistance appropriate for the specific finger usually operating it. The idea
it. The idea behind this adjusted design is to particularly reduce the load on behind this adjusted design is to particularly reduce the load on weaker fingers
weaker fingers and still pertain or even enhance typing and still pertain or even enhance typing performance. Additionally, we try to
performance. Additionally, we try to answer the question, whether or not a answer the question, whether or not a keyboard with, per finger, adjusted
keyboard with, per finger, adjusted actuation force has a positive impact on actuation force has a positive impact on efficiency and overall
efficiency and overall satisfaction. Thus, we evaluated the current availability satisfaction. Thus, we evaluated the current availability of resistances for
of resistances for mechanical keyswitches and conducted a preliminary telephone mechanical keyswitches and conducted a preliminary telephone interview (n = 17)
interview (n = 17) to assess preferences, use-cases and previous experiences to assess preferences, use-cases and previous experiences with
with keyboards. Further, we ran another preliminary experiment, where we keyboards. Further, we ran another preliminary experiment, where we measured the
measured the maximum applicable force for each finger in different positions maximum applicable force for each finger in different positions related to
related to keyboarding as a basis for our adjusted keyboard design. Lastly, keyboarding as a basis for our adjusted keyboard design. Lastly, during a three
during a three week laboratory user study with twenty-four participants, the week laboratory user study with twenty-four participants, the adjusted keyboard
adjusted keyboard design and three traditional keyboards with 35\,g, 50\,g and 80 design and three traditional keyboards with 35\,g, 50\,g and 80 g actuation
g actuation force were compared to each other in terms of performance and user force were compared to each other in terms of performance and user
satisfaction. The statistical analysis revealed, that especially error rates are satisfaction. The statistical analysis revealed, that especially error rates are
positively influenced by higher actuation forces and that keyboards with neither 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 too heavy nor to light resistance generally perform the best in terms of typing

21
acknowledgments.tex
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@ -1,4 +1,23 @@
%----------Danksagung/Acknowledgments-------------------------------------------------------------- %----------Danksagung/Acknowledgments--------------------------------------------------------------
\addsec{Acknowledgments} \addsec{Acknowledgments}
Hello (: Firstly, I want to thank all the 53 people that either participated in the over
two hour long main study, the preliminary finger force study, the preliminary
telephone interview or the crowdsourcing of the required texts for merely a
thanks or some 3D-printed goodies.
Furthermore, I want to thank my supervisor Prof. Dr. techn. Priv.-Doz. Andreas
Riener for his great input and guidance throughout this whole thesis. The always
fast and candid support regarding all my concerns was highly appreciated!
Further, I want to thank Prof. Dr. rer. nat. Franz Regensburger for the initial
feedback about all my ideas for a thesis, which helped me to ultimately decide
on this topic.
Additionally, I want to thank Eliis Lohoff, Nikola Brandl and Lukas Hanser for
proofreading my thesis.
Moreover, I want thank my girlfriend, mother and grandma for the emotional
support and all the encouraging words during my whole studies.
― Philip

6
chap2/literature_review.tex
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@ -55,7 +55,7 @@ Keyboards are well known input devices used to operate a computer. There are a
variety of keyboard types and models available on the market, some of which can variety of keyboard types and models available on the market, some of which can
be seen in Figure \ref{fig:keyboard_models}. The obvious difference between be seen in Figure \ref{fig:keyboard_models}. The obvious difference between
those keyboards in Figure \ref{fig:keyboard_models} is their general those keyboards in Figure \ref{fig:keyboard_models} is their general
appearance. The keyboards feature different enclosures and keycaps, which are appearance. The keyboards feature different enclosures and keycaps. Keycaps are
the rectangular pieces of plastic on top of the actual keyswitches that the rectangular pieces of plastic on top of the actual keyswitches that
sometimes indicate what letter, number or symbol, also known as characters, a sometimes indicate what letter, number or symbol, also known as characters, a
keypress should send to the computer. These keycaps are mainly made out of the keypress should send to the computer. These keycaps are mainly made out of the
@ -120,8 +120,8 @@ which sits on top of the spring and separates the two plates. The shape of the
stem, represented by the enlarged red lines in Figure stem, represented by the enlarged red lines in Figure
\ref{fig:mech_keyswitches_dissas}, defines the haptic feedback produced by the \ref{fig:mech_keyswitches_dissas}, defines the haptic feedback produced by the
keyswitch. When pressure is applied to the keycap, which is connected to the keyswitch. When pressure is applied to the keycap, which is connected to the
stem, the spring gets contracted and the stem moves downwards and thereby stops stem, the spring gets contracted and the stem moves downwards. Thereby, it stops
separating the two plates which closes the electrical circuit and sends a separating the two plates, which closes the electrical circuit and sends a
keypress to the computer. After the key is released, the spring pushes the stem keypress to the computer. After the key is released, the spring pushes the stem
back to its original position \cite{bassett_keycap, peery_3d_keyswitch, back to its original position \cite{bassett_keycap, peery_3d_keyswitch,
ergopedia_keyswitch, chen_mech_switch}. Usually, mechanical keyswitches are ergopedia_keyswitch, chen_mech_switch}. Usually, mechanical keyswitches are

23
chap4/methodology.tex
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@ -305,12 +305,13 @@ keyboard?.''}
\subsubsection{Method} \subsubsection{Method}
\label{sec:main_method} \label{sec:main_method}
In our laboratory study, twenty-four participants were required to perform two In our laboratory study, twenty-four participants were required to perform two
typing test with each of the four keyboards provided by us and two extra typing typing tests with each of the four keyboards provided by us and two extra typing
test with their own keyboards as a reference. The four keyboards differed only tests with their own keyboards as a reference. The four keyboards differed only
in actuation force and were the independent variable. The dependent variable in actuation force and were the independent variable. The dependent variable
were, typing speed (\gls{WPM} and \gls{KSPS}), error rate (\gls{CER}, \gls{TER}) were, typing speed (\gls{WPM} and \gls{KSPS}), error rate (\gls{CER},
and satisfaction (preference, usability, comfort, forearm muscle activity \gls{TER}), forearm muscle activity measured via \gls{EMG} and satisfaction
measured via \gls{EMG}, post experiment semi structured interview and ux-curves) (preference, usability, comfort, post experiment semi structured interview and
ux-curves).
\subsubsection{Participants} \subsubsection{Participants}
\label{sec:main_participants} \label{sec:main_participants}
@ -507,12 +508,12 @@ into our experiment. The first questionnaire was the \glsfirst{KCQ} provided by
\cite[56]{iso9241-411} and was filled out after each individual typing test \cite[56]{iso9241-411} and was filled out after each individual typing test
(\glsfirst{PTTQ}). The second survey, that was filled out every time the (\glsfirst{PTTQ}). The second survey, that was filled out every time the
keyboard was changed, was the \glsfirst{UEQ-S} \cite{schrepp_ueq_handbook} with keyboard was changed, was the \glsfirst{UEQ-S} \cite{schrepp_ueq_handbook} with
an additional question―``How satisfied have you been with this keyboard?''―that an additional question―\textit{``How satisfied have you been with this
could be answered with the help of a \gls{VAS} ranging from 0 to 100 keyboard?''}―that could be answered with the help of a \gls{VAS} ranging from
(\glsfirst{PKQ})\cite{lewis_vas}. Due to the limited time participants had to 0 to 100 (\glsfirst{PKQ})\cite{lewis_vas}. Due to the limited time participants
fill out the questionnaires in between typing tests (2 - 3 minutes) and also had to fill out the questionnaires in between typing tests (2 - 3 minutes) and
because participants had to rate multiple keyboards in one session, the short also because participants had to rate multiple keyboards in one session, the
version of the \gls{UEQ} was selected \cite{schrepp_ueq_handbook}. short version of the \gls{UEQ} was selected \cite{schrepp_ueq_handbook}.
\textbf{Post Experiment Interview \& \Gls{UX Curve}s} \textbf{Post Experiment Interview \& \Gls{UX Curve}s}

30
chap5/results.tex
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@ -358,7 +358,7 @@ the right flexor muscle (n = 22). We found no significant differences in
\gls{EMG} measurements. Further, we analyzed the effect of the individual \gls{EMG} measurements. Further, we analyzed the effect of the individual
keyboards on \%\gls{MVC}s separately for first and second typing tests (Tn\_1 \& keyboards on \%\gls{MVC}s separately for first and second typing tests (Tn\_1 \&
Tn\_2, n := 1, ..., 4), but did not find any statistically significant results Tn\_2, n := 1, ..., 4), but did not find any statistically significant results
as well. Lastly, we analyzed possible differences between \%\gls{MVC} either. Additionally, we analyzed possible differences between \%\gls{MVC}
measurements of first and second typing tests for each individual keyboard, measurements of first and second typing tests for each individual keyboard,
using either dependent T-tests or Wilcoxon Signed Rank Tests. There were no using either dependent T-tests or Wilcoxon Signed Rank Tests. There were no
statistically significant differences in \%\gls{MVC} between the first and the statistically significant differences in \%\gls{MVC} between the first and the
@ -367,11 +367,11 @@ test keyboards of the mean values for both typing tests combined can be observed
in Table \ref{tbl:sum_tkbs_emg}. Lastly, we created histograms (Figure in Table \ref{tbl:sum_tkbs_emg}. Lastly, we created histograms (Figure
\ref{fig:max_emg_tkbs}) for each of the observed muscle groups, that show the \ref{fig:max_emg_tkbs}) for each of the observed muscle groups, that show the
number of times a keyboard yielded the highest \%\gls{MVC} out of all keyboards number of times a keyboard yielded the highest \%\gls{MVC} out of all keyboards
for each participant. We found, that \textit{Athena} most frequently ($\approx$45\,\%) for each participant. We found that \textit{Athena} most frequently
produced the highest extensor muscle activity for both arms. The highest muscle ($\approx$45\,\%) produced the highest extensor muscle activity for both
activity for both flexor muscle groups was evenly distributed among all test arms. The highest muscle activity for both flexor muscle groups was evenly
keyboards with a slight exception of \textit{Nyx}, which produced the highest distributed among all test keyboards with a slight exception of \textit{Nyx},
\%\gls{MVC} only in ~14\,\% of participants. which produced the highest \%\gls{MVC} only in ~14\,\% of participants.
\begin{figure}[H] \begin{figure}[H]
\centering \centering
@ -449,7 +449,7 @@ keyboards with a slight exception of \textit{Nyx}, which produced the highest
\label{sec:res_kcq} \label{sec:res_kcq}
The \glsfirst{KCQ} was filled out by the participants after each individual The \glsfirst{KCQ} was filled out by the participants after each individual
typing test. The questionnaire featured twelve questions regarding the typing test. The questionnaire featured twelve questions regarding the
previously used keyboard which are labelled as follows: previously used keyboard which are labeled as follows:
\begin{table}[H] \begin{table}[H]
\centering \centering
@ -524,7 +524,7 @@ eight questions on a 7-point Likert scale, which formed two scales (pragmatic,
hedonic). Additionally we added one extra question that could be answered on a hedonic). Additionally we added one extra question that could be answered on a
\glsfirst{VAS} from 0 to 100. The survey was filled out after both tests with a \glsfirst{VAS} from 0 to 100. The survey was filled out after both tests with a
keyboard have been completed. The questions of our modified \gls{UEQ-S} were keyboard have been completed. The questions of our modified \gls{UEQ-S} were
labelled as follows: labeled as follows:
\begin{table}[H] \begin{table}[H]
\centering \centering
@ -648,25 +648,25 @@ stable if \gls{SP} = \gls{EP} (margin of $\pm$ 1 mm). One curve can either
represent one typing test (C1 or C2) or the whole experience with one keyboard represent one typing test (C1 or C2) or the whole experience with one keyboard
over the course of both typing tests (C12). All curves can be observed in over the course of both typing tests (C12). All curves can be observed in
Appendix \ref{app:uxc} and the resulting slopes for all curve types are shown in Appendix \ref{app:uxc} and the resulting slopes for all curve types are shown in
Figure \ref{fig:res_uxc}. During the semi-structured interview, we asked the Figure \ref{fig:res_uxc}. During the semi-structured interview we asked the
participants to rank the keyboards from 1 (favorite) to 5 (least favorite). If participants to rank the keyboards from 1 (favorite) to 5 (least favorite). If
in doubt, participants were allowed to place two keyboards on the same in doubt, participants were allowed to place two keyboards on the same
rank. Further, we asked some participants (n = 19) to also rank the keyboards rank. Further, we asked some participants (n = 19) to also rank the keyboards
from lowest actuation force (one) to highest actuation force (five). The from lowest actuation force (one) to highest actuation force (five). The
participants own keyboard was four times more often placed first than any other participants own keyboard was four times more often placed first than any other
keyboard. \textit{Hera} was the only keyboard, that never got placed fifth and keyboard. \textit{Hera} was the only keyboard that never got placed fifth and
except for \textit{Own}, was the most represented keyboard in the top three. The except for \textit{Own}, was the most represented keyboard in the top three. The
ranking of the perceived actuation force revealed, that participants were able ranking of the perceived actuation force revealed that participants were able
to identify \textit{Nyx} (35\,g) and \textit{Athena} (80\,g) as the keyboards with to identify \textit{Nyx} (35\,g) and \textit{Athena} (80\,g) as the keyboards
the lowest and highest actuation force respectively. All results for both with the lowest and highest actuation force respectively. All results for both
rankings are visualized in Figure \ref{fig:res_interview}. Lastly, we analyzed rankings are visualized in Figure \ref{fig:res_interview}. Lastly, we analyzed
the recordings of all interviews and found several similar statements about the recordings of all interviews and found several similar statements about
specific keyboards. Twelve participants noted, that because of the new form specific keyboards. Twelve participants noted that because of the new form
factor of the test keyboards, additional familiarization was required to feel factor of the test keyboards, additional familiarization was required to feel
comfortable. Nine of those specifically mentioned the height of the keyboard as comfortable. Nine of those specifically mentioned the height of the keyboard as
the main difference. Fourteen subjects reported―\textit{``Because Nyx had such a the main difference. Fourteen subjects reported―\textit{``Because Nyx had such a
low resistance, I kept making mistakes!''}. Four participants explicitly low resistance, I kept making mistakes!''}. Four participants explicitly
noted, that \textit{Hera} felt very pleasant and two subjects mentioned noted that \textit{Hera} felt very pleasant and two subjects mentioned
\textit{``I had really good flow.''} and \textit{``It somehow just felt \textit{``I had really good flow.''} and \textit{``It somehow just felt
right''}. Ten participants reported, that typing on \textit{Athena} was right''}. Ten participants reported, that typing on \textit{Athena} was
exhausting. \textit{Aphrodite} was not mentioned as often as the other keyboards exhausting. \textit{Aphrodite} was not mentioned as often as the other keyboards

171
chap6/discussion.tex
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@ -9,38 +9,39 @@ question \textit{``Does an adjusted actuation force per key have a positive
\subsection{Impact of Actuation Force on Typing Speed} \subsection{Impact of Actuation Force on Typing Speed}
\label{sec:dis_speed} \label{sec:dis_speed}
Our main experiment yielded, that there are differences in typing speed for both Our main experiment yielded that there are differences in typing speed for both
metrics related to transcribed text we measured―namely \glsfirst{WPM} and metrics related to transcribed text we measured―namely \glsfirst{WPM} and
\glsfirst{AdjWPM}. Especially the keyboard with the lowest uniform actuation \glsfirst{AdjWPM}. Especially the keyboard with the lowest uniform actuation
force of 35\,g―\textit{Nyx}―performed worse than all other keyboards. In terms force of 35\,g―\textit{Nyx}―performed worse than all other keyboards. In terms
of \gls{WPM}, \textit{Nyx (35\,g)} was on average 4.1\,\% slower than of \gls{WPM}, \textit{Nyx (35\,g)} was on average 4.1\,\% slower than
\textit{Athena (80\,g)} and \textit{Aphrodite (50\,g)} and 4.8\,\% slower than the \textit{Athena (80\,g)} and \textit{Aphrodite (50\,g)} and 4.8\,\% slower than
adjusted keyboard \textit{Hera (35 - 60\,g)}. Similarly, for \gls{AdjWPM}, the adjusted keyboard \textit{Hera (35 - 60\,g)}. Similarly, for \gls{AdjWPM},
\textit{Nyx} was 4.3\,\% slower than \textit{Athena} and \textit{Aphrodite} and \textit{Nyx} was 4.3\,\% slower than \textit{Athena} and \textit{Aphrodite} and
4.9\,\% slower than \textit{Hera}. The 4\,\% to 5\,\% difference in \gls{WPM} and 4.9\,\% slower than \textit{Hera}. The 4\,\% to 5\,\% difference in \gls{WPM}
\gls{AdjWPM} in our sample account for approximately 2 words per minute. When and \gls{AdjWPM} in our sample account for approximately two words per
extrapolated with the mean daily keyboard usage of 6.69 hours reported by our minute. When extrapolated with the mean daily keyboard usage of 6.69 hours
participants, this difference would be as big as 803 words, which when put into reported by our participants, this difference would be as big as 803 words,
perspective, is equivalent to roughly two full pages of only written content which when put into perspective, is equivalent to roughly two full pages of only
(11pt font size). Although, this specific example would assume constant typing written content (11pt font size). Although, this specific example would assume
for 6.69 hours, it is still a useful estimate of the loss in productivity under constant typing for 6.69 hours, it is still a useful estimate of the loss in
normal working conditions over the course of several days. These differences in productivity under normal working conditions over the course of several
\gls{WPM} and \gls{AdjWPM} could be explained by the higher error rates and days. These differences in \gls{WPM} and \gls{AdjWPM} could be explained by the
thereby the loss of ``typing flow'' we discuss in the next section. \gls{KSPS} higher error rates and thereby the loss of ``typing flow'' we discuss in the
reflects the raw input speed by including backspaces and previously deleted next section. \gls{KSPS} reflects the raw input speed by including backspaces
characters. The reason we included \gls{KSPS} in our analysis was to reveal and previously deleted characters. The reason we included \gls{KSPS} in our
possible differences in the physical speed participants type on a keyboard and analysis was to reveal possible differences in the physical speed participants
not to further asses speed in the sense of productivity. We could not find any type on a keyboard and not to further asses speed in the sense of
statistically significant differences in \gls{KSPS} but saw a trend, indicating productivity. We could not find any statistically significant differences in
that subjects typed a bit slower (< 3\,\%) on \textit{Athena (80\,g)} compared to \gls{KSPS} but saw a trend, indicating that subjects typed a bit slower (<
\textit{Aphrodite (50\,g)} and \textit{Hera (35 - 60\,g)}. With the differences 3\,\%) on \textit{Athena (80\,g)} compared to \textit{Aphrodite (50\,g)} and
in metrics that are commonly used to measure typing speed more closely related \textit{Hera (35 - 60\,g)}. With the differences in metrics that are commonly
to productivity (\gls{WPM}, \gls{AdjWPM}) and the trends that indicate a slight used to measure typing speed more closely related to productivity (\gls{WPM},
difference in operating speed we could have accepted our hypothesis. However, \gls{AdjWPM}) and the trends that indicate a slight difference in operating
with the relation between error rate and typing speed described in the next speed we could have accepted our hypothesis. However, with the relation between
section and the thereby rather indirect effect of the actuation force, we can error rate and typing speed described in the next section and the thereby rather
only partially accept our hypothesis that a difference solely in actuation indirect effect of the actuation force, we can only partially accept our
force, has an impact on typing speed. hypothesis that a difference solely in actuation force, has an impact on typing
speed.
\begin{phga_hyp*}[1 $\rightarrow$ \cmark\kern-1.1ex\raisebox{.7ex}{\rotatebox[origin=c]{125}{--}}] \begin{phga_hyp*}[1 $\rightarrow$ \cmark\kern-1.1ex\raisebox{.7ex}{\rotatebox[origin=c]{125}{--}}]
Actuation force has an impact on typing speed (efficiency - speed). Actuation force has an impact on typing speed (efficiency - speed).
@ -59,17 +60,18 @@ force, has an impact on typing speed.
As already briefly mentioned in Section \ref{sec:dis_speed}, measured error As already briefly mentioned in Section \ref{sec:dis_speed}, measured error
rates like \glsfirst{UER}, \glsfirst{CER} and \glsfirst{TER} differed especially rates like \glsfirst{UER}, \glsfirst{CER} and \glsfirst{TER} differed especially
between \textit{Nyx (35\,g)} and the other test keyboards. The statistical between \textit{Nyx (35\,g)} and the other test keyboards. The statistical
analyses further revealed, that \textit{Athena}, the keyboard with the highest analyses further revealed that \textit{Athena}, the keyboard with the highest
actuation force of 80\,g, produced on average 1\,\% less \gls{TER} than actuation force of 80\,g, produced on average 1\,\% less \gls{TER} than
\textit{Hera (35 - 60\,g)} and \textit{Aphrodite (50\,g)} and 3\,\% less than \textit{Hera (35 - 60\,g)} and \textit{Aphrodite (50\,g)} and 3\,\% less than
\textit{Nyx (35\,g)}. Furthermore, \textit{Hera} and \textit{Aphrodite} both had a \textit{Nyx (35\,g)}. Furthermore, \textit{Hera} and \textit{Aphrodite} both had
2\,\% lower \gls{TER} than \textit{Nyx}. Additionally to the quantitative results, a 2\,\% lower \gls{TER} than \textit{Nyx}. Additionally to the quantitative
fourteen of the twenty-four participants also reported, that \textit{Nyx's} results, fourteen of the twenty-four participants also reported, that
light actuation force was the reason for many accidental key presses. It further \textit{Nyx's} light actuation force was the reason for many accidental key
stood out, that as shown in Figure \ref{fig:max_opc_ter}, \textit{Athena} was presses. It further stood out that, as shown in Figure \ref{fig:max_opc_ter},
the most accurate keyboard for 58\,\% of participants and also more accurate than \textit{Athena} was the most accurate keyboard for 58\,\% of participants and
keyboard \textit{Own} for eleven of the subjects. Overall, this concludes, that also more accurate than keyboard \textit{Own} for eleven of the
a higher actuation force has a positive impact on error rate. subjects. Overall, this concludes that a higher actuation force has a positive
impact on error rate.
\begin{phga_hyp*}[2 $\rightarrow$ \cmark] \begin{phga_hyp*}[2 $\rightarrow$ \cmark]
Higher key actuation force decreases typing errors compared to lower key Higher key actuation force decreases typing errors compared to lower key
@ -80,13 +82,13 @@ a higher actuation force has a positive impact on error rate.
The higher error rates and the possibility to correct erroneous input could have The higher error rates and the possibility to correct erroneous input could have
also been a factor that led to lower \textit{WPM}. To evaluate the likelihood of also been a factor that led to lower \textit{WPM}. To evaluate the likelihood of
this additional relation, we conducted a \gls{LRT} of fixed effects for our this additional relation we conducted a \gls{LRT} of fixed effects for our
linear mixed-effects model with two random effects (participant and first/second linear mixed-effects model with two random effects (participant and first/second
typing test), fixed effect \gls{TER} and response variable \gls{WPM}. The typing test), fixed effect \gls{TER} and response variable \gls{WPM}. The
results of the \gls{LRT} ($\chi^2(1)$ = 110.44, p = 0.00000000000000022) results of the \gls{LRT} ($\chi^2(1)$ = 110.44, p = 0.00000000000000022)
together with the trends of lower \gls{WPM} with increasing \gls{TER}, visible together with the trends of lower \gls{WPM} with increasing \gls{TER}, visible
in Figure \ref{fig:reg_ter_wpm}, suggest, that the \gls{TER} indeed had an in Figure \ref{fig:reg_ter_wpm}, suggest that the \gls{TER} indeed had an
impact on \gls{WPM}. This could have been, because every time an error was made, impact on \gls{WPM}. This could have been because every time an error was made,
almost all participants decided to correct it right away. With a higher error almost all participants decided to correct it right away. With a higher error
rate, this obviously leads to many short interruptions and an increased number rate, this obviously leads to many short interruptions and an increased number
of characters that are not taken into account when computing the \gls{WPM} of characters that are not taken into account when computing the \gls{WPM}
@ -108,7 +110,7 @@ We tried to narrow down the rather broad term ``satisfaction'' to individual
categories that we, with the information gathered through our literature review categories that we, with the information gathered through our literature review
and telephone interviews, defined as necessary for a positive user experience and telephone interviews, defined as necessary for a positive user experience
while using a keyboard \cite{giese_sati}. We decided for the following metrics while using a keyboard \cite{giese_sati}. We decided for the following metrics
to evaluate, whether or not a user experience with a keyboard that features to evaluate whether or not a user experience with a keyboard that features
lighter actuation forces was more satisfactory: lighter actuation forces was more satisfactory:
\begin{table}[H] \begin{table}[H]
@ -129,26 +131,26 @@ lighter actuation forces was more satisfactory:
As described in Section \ref{sec:res_ueqs}, we could not find statistically As described in Section \ref{sec:res_ueqs}, we could not find statistically
significant differences for any of the test keyboards regarding the pragmatic significant differences for any of the test keyboards regarding the pragmatic
scale of the \gls{UEQ-S}. From visual assessment of the graph shown in Figure scale of the \gls{UEQ-S}. From visual assessment of the graph shown in Figure
\ref{fig:ueq_tkbs_res} we could conclude, that there is a slight trend towards a \ref{fig:ueq_tkbs_res} we could conclude that there is a slight trend towards a
more positive rating for keyboards that utilized keyswitches with higher more positive rating for keyboards that utilized keyswitches with higher
actuation forces than \textit{Nyx (35\,g)}. This trend in the opposite direction actuation forces than \textit{Nyx (35\,g)}. This trend in the opposite direction
of our hypothesized outcome, that lighter actuation force leads to more user of our hypothesized outcome that lighter actuation force leads to more user
satisfaction, could be due to the longer familiarization time required for satisfaction, could be due to the longer familiarization time required for
keyboards with very light actuation force \cite{gerard_keyswitch}. keyboards with very light actuation force \cite{gerard_keyswitch}.
\textbf{[\xmark] Additional Question of Satisfaction with Keyboard} \textbf{[\xmark] Additional Question of Satisfaction with Keyboard}
The results deduced from the additional question \textit{``How satisfied have The results deduced from the additional question \textit{``How satisfied have
you been with this keyboard?''}, which could be answered on a \glsfirst{VAS} you been with this keyboard?''}, which were answered on a \glsfirst{VAS}
from 0 to 100 after both tying tests with a keyboard, suggested that \textit{Nyx from 0 to 100 after both tying tests with a keyboard, suggested that \textit{Nyx
(35\,g)}, the keyboard with the lightest actuation force and also (35\,g)}, the keyboard with the lightest actuation force and also
\textit{Athena (80\,g)} the keyboard with the highest actuation force, were rated \textit{Athena (80\,g)} the keyboard with the highest actuation force, were rated
significantly worse than \textit{Aphrodite (50\,g)}. Additionally, \textit{Hera significantly worse than \textit{Aphrodite (50\,g)}. Additionally, \textit{Hera
(35 - 60\,g)}, the adjusted keyboard showed a trend towards a significantly (35 - 60\,g)}, the adjusted keyboard, showed a trend towards a significantly
better rating than \textit{Nyx}. These results indicate, that neither of the better rating than \textit{Nyx}. These results indicate that neither of the
keyboards with extreme actuation forces were perceived as a overwhelmingly keyboards with extreme actuation forces were perceived as a overwhelmingly
pleasant keyboard to use during our typing tests. This is further supported by pleasant keyboard to use during our typing tests. This is further supported by
the visualisation of the mean ratings in Figure \ref{fig:res_tkbs_sati} where the visualization of the mean ratings in Figure \ref{fig:res_tkbs_sati} where
the average ratings for \textit{Aphrodite} and \textit{Hera} were approximately the average ratings for \textit{Aphrodite} and \textit{Hera} were approximately
10 points higher than those for \textit{Nyx} and \textit{Athena}. 10 points higher than those for \textit{Nyx} and \textit{Athena}.
@ -159,11 +161,11 @@ questions related to effort or fatigue while operating a keyboard,
\textit{Athena (80\,g)} received significantly lower ratings than the other test \textit{Athena (80\,g)} received significantly lower ratings than the other test
keyboards. Additionally to the measured differences in error rates discussed in keyboards. Additionally to the measured differences in error rates discussed in
Section \ref{sec:dis_error}, we discovered that participants also perceived the Section \ref{sec:dis_error}, we discovered that participants also perceived the
accuracy of \textit{Athena (80\,g)} and \textit{Aphrodite (50\,g)} higher compared accuracy of \textit{Athena (80\,g)} and \textit{Aphrodite (50\,g)} higher
to \textit{Nyx (35\,g)}. Similarly to the results discussed in the last compared to \textit{Nyx (35\,g)}. Similarly to the results discussed in the last
paragraph, the scores of the two keyboards with extreme actuation forces, paragraph, the scores of the two keyboards with extreme actuation forces,
\textit{Nyx (35\,g)} and \textit{Athena (80\,g)} fluctuated quite a bit and on \textit{Nyx (35\,g)} and \textit{Athena (80\,g)}, fluctuated quite a bit and, on
average those two keyboards scored lower than \textit{Aphrodite (50\,g)} or average both keyboards scored lower than \textit{Aphrodite (50\,g)} or
\textit{Hera (35 - 60\,g)} (Figure \ref{fig:kcq_tkbs_res}). Thereby, these \textit{Hera (35 - 60\,g)} (Figure \ref{fig:kcq_tkbs_res}). Thereby, these
results do not indicate a clear trend towards enhanced user experience when results do not indicate a clear trend towards enhanced user experience when
using keyboards with lower actuation forces. using keyboards with lower actuation forces.
@ -191,15 +193,15 @@ Lastly, we analysed all recordings of the post-experiment interviews and
categorized the feedback given for each keyboard into positive and negative categorized the feedback given for each keyboard into positive and negative
responses. We then calculated a ratio of these responses, which can be seen in responses. We then calculated a ratio of these responses, which can be seen in
Figure \ref{fig:ratio_interview}, to evaluate preferences towards specific Figure \ref{fig:ratio_interview}, to evaluate preferences towards specific
keyboards, that could not be expressed by our participants through any other keyboards that could not be expressed by our participants through any other
supplied method during the experiment. Like all other factors we identified as supplied method during the experiment. Like all other factors we identified as
reasonable indicators for satisfaction, these ratios yielded, that neither reasonable indicators for satisfaction, these ratios yielded, that neither
\textit{Athena (80\,g)} nor \textit{Nyx (35\,g)} received more positive than \textit{Athena (80\,g)} nor \textit{Nyx (35\,g)} received more positive than
negative feedback. It should be noted, that previous research has shown that negative feedback. It should be noted, that previous research has shown that
people tend to remember and process bad experiences more thorough than good people tend to remember and process bad experiences more thorough than good
ones, which could be a reason for the increased number of negative feedback for ones, which could be a reason for the increased number of negative feedback for
\textit{Nyx} and \textit{Athena} but would also indicate a worse experience with \textit{Nyx} and \textit{Athena}, but would also indicate a worse experience
those two keyboards \cite{baumeister_bad}. with those two keyboards \cite{baumeister_bad}.
\begin{figure}[H] \begin{figure}[H]
\centering \centering
@ -211,16 +213,16 @@ those two keyboards \cite{baumeister_bad}.
\textbf{Conclusion} \textbf{Conclusion}
Contrary to the responses of our preliminary telephone interview, where 76\,\% of Contrary to the responses of our preliminary telephone interview, where 76\,\%
attendees preferred a keyboard with light actuation force, none of the factors of attendees preferred a keyboard with light actuation force, none of the
we defined as relevant for user satisfaction suggests, that keyboards with lower factors we defined as relevant for user satisfaction suggests that keyboards
actuation force are more satisfactory to use than keyboards with higher with lower actuation force are more satisfactory to use than keyboards with
actuation force. Therefore, we have to fully reject our hypothesis. We can higher actuation force. Therefore, we have to fully reject our hypothesis. We
conclude thought, that keyboards with actuation forces in between those two can conclude thought that keyboards with actuation forces in between those two
extremes (35\,g / 80\,g), are persistently perceived as more pleasant to use and extremes (35\,g / 80\,g), are persistently perceived as more pleasant to use and
that ratings keyboards with extreme actuation forces are highly influenced by that ratings of keyboards with extreme actuation forces are highly influenced by
personal preference, which is indicated by the high fluctuation of almost all personal preference. The latter is indicated by the high fluctuation of almost
responses regarding our evaluated factors. all responses regarding our evaluated factors.
\begin{phga_hyp*}[3 $\rightarrow$ \xmark] \begin{phga_hyp*}[3 $\rightarrow$ \xmark]
Keys with lower actuation force are perceived as more satisfactory to type Keys with lower actuation force are perceived as more satisfactory to type
@ -229,12 +231,12 @@ responses regarding our evaluated factors.
\subsection{Impact of Actuation Force on Muscle Activity} \subsection{Impact of Actuation Force on Muscle Activity}
\label{sec:dis_emg} \label{sec:dis_emg}
In contrast to other studies that suggested, that actuation force has an impact In contrast to other studies that suggested that actuation force has an impact
on muscle activity, we could not identify significant differences in terms of \% on muscle activity, we could not identify significant differences in terms of \%
of \glsfirst{MVC} for any of our \gls{EMG} measurements. Only a slight trend, of \glsfirst{MVC} for any of our \gls{EMG} measurements. Only a slight trend
that \textit{Nyx (35\,g)} produced the highest flexor \%\gls{MVC} for only 14\,\% that \textit{Nyx (35\,g)} produced the highest flexor \%\gls{MVC} for only
of participants, could be interpreted as anecdotal evidence towards our 14\,\% of participants, could be interpreted as anecdotal evidence towards our
hypothesis, that actuation force has an impact on muscle activity. Therefore we hypothesis that actuation force has an impact on muscle activity. Therefore, we
have to reject our hypothesis. have to reject our hypothesis.
\begin{phga_hyp*}[4 $\rightarrow$ \xmark] \begin{phga_hyp*}[4 $\rightarrow$ \xmark]
@ -251,7 +253,7 @@ As discussed in the previous sections, there were no statistically significant
differences in terms of satisfaction for any of the test keyboards, including differences in terms of satisfaction for any of the test keyboards, including
our adjusted keyboard \textit{Hera}. Still, the rather unconventional design our adjusted keyboard \textit{Hera}. Still, the rather unconventional design
choice of non-uniform actuation forces across a keyboard did not negatively choice of non-uniform actuation forces across a keyboard did not negatively
influence the satisfaction compared to \textit{Aphrodite} which was often influence the satisfaction compared to \textit{Aphrodite}, which was often
perceived as equivalent to the participant's own keyboard. In fact, perceived as equivalent to the participant's own keyboard. In fact,
\textit{Hera} was the keyboard with the most occurrences in the top three, tied \textit{Hera} was the keyboard with the most occurrences in the top three, tied
first place with \textit{Aphrodite} and was never ranked 4th place during the first place with \textit{Aphrodite} and was never ranked 4th place during the
@ -263,10 +265,10 @@ familiarization period required by keyboards with lighter actuation forces
reported a currently present disease of the left arm and wrist (Syndrome Sudeck, reported a currently present disease of the left arm and wrist (Syndrome Sudeck,
complex regional pain syndrome (CRPS)), ranked Hera 30 points higher than all complex regional pain syndrome (CRPS)), ranked Hera 30 points higher than all
other keyboards. \textit{I3Z4XI7H} also reported in the post-experiment other keyboards. \textit{I3Z4XI7H} also reported in the post-experiment
interview, that \textit{Hera} was surprisingly pleasant to use and that pain was interview that \textit{Hera} was surprisingly pleasant to use and that pain was
significantly lower than with all other keyboards including significantly lower than with all other keyboards including
\textit{Own}. However, because of the nearly identical scores to \textit{Own}. However, because of the nearly identical scores to
\textit{Aphrodite} in almost all categories, we have to reject our hypothesis, \textit{Aphrodite} in almost all categories, we have to reject our hypothesis
that an adjusted keyboard is more satisfactory to use than standard keyboards. that an adjusted keyboard is more satisfactory to use than standard keyboards.
\begin{phga_hyp*}[7 $\rightarrow$ \xmark] \begin{phga_hyp*}[7 $\rightarrow$ \xmark]
@ -274,19 +276,20 @@ that an adjusted keyboard is more satisfactory to use than standard keyboards.
to standard keyboards. to standard keyboards.
\end{phga_hyp*} \end{phga_hyp*}
Similarly, the resulting error rates measured for \textit{Hera (35 - 60\,g)} were Similarly, the resulting error rates measured for \textit{Hera (35 - 60\,g)}
close to equal to the results of \textit{Aphrodite (50\,g)} and for speed related were close to equal to the results of \textit{Aphrodite (50\,g)} and for speed
metrics between those two keyboards only slight improvements while using related metrics between those two keyboards only slight improvements while using
\textit{Hera} in \gls{WPM} (0.8\,\%), \gls{AdjWPM} (0.6\,\%) and \gls{KSPS} (1\,\%)― \textit{Hera} in \gls{WPM} (0.8\,\%), \gls{AdjWPM} (0.6\,\%) and \gls{KSPS}
that were not statistically significant―were recorded during our experiment. It (1\,\%)― that were not statistically significant―were recorded during our
was still interesting to see, that \textit{Hera} was the fastest, out of all experiment. It was still interesting to see, that \textit{Hera}, out of all four
four test keyboards, for eleven (45\,\%) out of the twenty-four subjects and that test keyboards, was the fastest for eleven (45\,\%) out of the twenty-four
albeit the usage of 30\,\% keyswitches\footnote{That were actually pressed during subjects and that albeit the usage of 30\,\% keyswitches\footnote{That were
our typing tests} that required 35 - 40\,g actuation force, which is similar to actually pressed during our typing tests} that required 35 - 40\,g actuation
the actuation force of \textit{Nyx (35\,g)}, we did not see comparably high error force, which is similar to the actuation force of \textit{Nyx (35\,g)}, we did
rates. Because of the lacking evidence, that an adjusted keyboard produces less not see comparably high error rates. Because of the lacking evidence, that an
errors or supports the typist in achieving higher typing speeds, we have to adjusted keyboard produces less errors or supports the typist in achieving
reject our two hypotheses regarding those improvements. higher typing speeds, we have to reject our two hypotheses regarding those
improvements.
\begin{phga_hyp*}[5 $\rightarrow$ \xmark] \begin{phga_hyp*}[5 $\rightarrow$ \xmark]
An adjusted keyboard improves typing speed compared to standard keyboards An adjusted keyboard improves typing speed compared to standard keyboards
@ -298,7 +301,7 @@ reject our two hypotheses regarding those improvements.
to standard keyboards. to standard keyboards.
\end{phga_hyp*} \end{phga_hyp*}
Our experiment basically revealed, that keyboards which utilized keyswitches Our experiment basically revealed that keyboards which utilized keyswitches
with actuation forces that were neither too light (35\,g) nor too heavy (80\,g), with actuation forces that were neither too light (35\,g) nor too heavy (80\,g),
generally outperformed keyboards which featured those extreme actuation generally outperformed keyboards which featured those extreme actuation
forces. In the following section, we elaborate on possible limitations of our forces. In the following section, we elaborate on possible limitations of our

45
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@ -16,21 +16,21 @@ actuation force. Especially the keyboard with very low actuation force,
\textit{Nyx (35\,g)}, which also had the highest average error rate was \textit{Nyx (35\,g)}, which also had the highest average error rate was
significantly slower than all other keyboards. Therefore, we investigated, if significantly slower than all other keyboards. Therefore, we investigated, if
there is a connection between high error rates and stagnating typing speed and there is a connection between high error rates and stagnating typing speed and
found, that in general, the error rate was a factor for lower input found that in general, the error rate was a factor for lower input
rates. Neither the satisfaction nor the muscle activity was significantly rates. Neither the satisfaction nor the muscle activity was significantly
influenced solely by the actuation. influenced solely by the actuation.
In conclusion, our study showed, that the keyboard with non-uniform actuation In conclusion, our study showed that the keyboard with non-uniform actuation
forces―\textit{Hera (35 - 60\,g)}―was not able to improve the overall typing forces―\textit{Hera (35 - 60\,g)}―was not able to improve the overall typing
experience significantly enough to supersede existing designs, but was still a experience significantly enough to supersede existing designs, but was still a
viable alternative to all traditional keyboards we tested. It could be possible, viable alternative to all traditional keyboards we tested. It could be possible
that due to the unconventional force distribution, that is similar to keyboards that due to the unconventional force distribution, that is similar to keyboards
with very light actuation force, the muscle activity while using \textit{Hera} with very light actuation force, the muscle activity while using \textit{Hera}
could decrease when users are given more time to adapt to this keyboard could decrease when users are given more time to adapt to this keyboard
\cite{gerard_keyswitch}. Additionally, we found that keyboards with either very \cite{gerard_keyswitch}. Additionally, we found that keyboards with either very
high (80\,g) or very low (35\,g) actuation forces had the most influence on typing high (80\,g) or very low (35\,g) actuation forces had the most influence on
related metrics, when compared to the more commonly sold keyboards with around typing related metrics, when compared to the more commonly sold keyboards with
50\,g to 60\,g actuation force. In the next sections we identify possible around 50\,g to 60\,g actuation force. In the next sections we identify possible
limitations and propose some ideas on how to reevaluate custom keyboard designs limitations and propose some ideas on how to reevaluate custom keyboard designs
in future studies. in future studies.
@ -45,16 +45,16 @@ the researcher was in the same room, the limited time for the individual typing
tests and the rather short breaks in between typing tests, could have influenced tests and the rather short breaks in between typing tests, could have influenced
some subjects by inducing unnecessary stress. Another limitation related to the some subjects by inducing unnecessary stress. Another limitation related to the
preliminary finger strength study, was the very small number of participants (n preliminary finger strength study, was the very small number of participants (n
= 6). Although we measured the finger strengths in different positions for 50\,\% = 6). Although we measured the finger strengths in different positions for
female and male participants, the age distribution was not diverse (M = 24) and 50\,\% female and male participants, the age distribution was not diverse (M =
with a higher number of subjects, the results would have been much more 24) and with a higher number of subjects, the results would have been much more
reliable. Similarly, the number and diversity in occupation of participants reliable. Similarly, the number and diversity in occupation of participants
could have been higher for our main study (n = 24) to yield even more meaningful could have been higher for our main study (n = 24) to yield even more meaningful
results. The low number of participants in general was partly due to the ongoing results. The low number of participants in general was partly due to the ongoing
COVID-19 pandemic. Lastly, we could have used more linear mixed models during COVID-19 pandemic. Lastly, we could have used more linear mixed models during
our statistical analysis, to be able to make statements about the influence of our statistical analysis, to be able to make statements about the influence of
other factors e.g., age, gender, average daily keyboard usage, etc., on speed, other factors e.g., age, gender, average daily keyboard usage, etc., on speed,
error rate and satisfaction. error rate or satisfaction.
\subsection{Future work} \subsection{Future work}
\label{sec:fw} \label{sec:fw}
@ -62,17 +62,18 @@ We propose, that in further research related to keyboards with non-uniform
actuation force (adjusted keyboards), participants should test several different actuation force (adjusted keyboards), participants should test several different
adjusted keyboards and the results should be compared to one identical looking adjusted keyboards and the results should be compared to one identical looking
keyboard that utilizes a uniform layout of keyswitches with an actuation force keyboard that utilizes a uniform layout of keyswitches with an actuation force
of 50\,g to 65\,g. Further, different adjusted layouts, with e.g. higher or lower of 50\,g to 65\,g. Further, different adjusted layouts, with e.g. higher or
base actuation force than 50\,g could be used to calculate the individual spring lower base actuation force than 50\,g could be used to calculate the individual
resistances used for each key or a similar layout to the one used in spring resistances used for each key or a similar layout to the one used in
Realforce\footnote{\url{https://www.realforce.co.jp/en/products/}} keyboards, Realforce\footnote{\url{https://www.realforce.co.jp/en/products/}} keyboards,
could be compared to each other. Furthermore, long term studies with adjusted could be compared to each other. Furthermore, long term studies with adjusted
keyboards, where participants use the adjusted keyboard for 3 to 4 months and keyboards where participants use the adjusted keyboard for three to four months
then use a uniform keyboard they prefer for another 3 to 4 months as their daily and then use a uniform keyboard they prefer for another three to four months as
driver, could yield more accurate results, due to the chance to fully adapt to their daily driver, could yield more accurate results, due to the chance to
the individual keyboards. During those months \gls{EMG} and typing related fully adapt to the individual keyboards. During those months \gls{EMG} and
metrics should be measured on a regular basis. Lastly, it would be interesting typing related metrics should be measured on a regular basis. Lastly, it would
to investigate if an adjusted keyboard can reduce pain or at least enhance be interesting to investigate if an adjusted keyboard can reduce pain or at
comfort for typists with pre-existing diseases influenced by typing activities least enhance comfort for typists with pre-existing diseases influenced by
(disorders of the upper extremity), since one of our participants with a similar typing activities (disorders of the upper extremity), since one of our
disease reported a great reduction in pain while using \textit{Hera}. participants with a similar disease reported a great reduction in pain while
using \textit{Hera}.

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@ -1,12 +0,0 @@
%----------Sperrvermerk/Confidentiality clause------------------------------------------------------------
\addsec{Sperrvermerk/Confidentiality clause}
Optional.\\
Ingolstadt, \rule{0.3\textwidth}{0.4pt} \\
\textcolor{white}{.}\qquad\qquad\qquad\qquad\quad \small (Date) \\ [1.3cm]
(Signature) \\
Firstname Lastname

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@ -1,19 +0,0 @@
% Kapitel 7 - Ausblick
%\newgeometry{textheight=\paperheight, textwidth=\paperwidth}
%\begin{titlepage}
% %----THI-Bertrandt-logo--------------------------------------------------------
% \begin{figure}[h!]
% \centering
% \includegraphics[width={\textwidth}]{titeltrenner/t7}
% \end{figure}
% %------------------------------------------------------------------------------
%\end{titlepage}
%\restoregeometry
%%--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\section{Ausblick}
\subsection{Einschränkungen}

2
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@ -35,7 +35,7 @@
Name and Surname: & \textbf{Philip Gaber} \\ [3em] Name and Surname: & \textbf{Philip Gaber} \\ [3em]
Issued on: & 08.04.2021 \\ [1em] % issuing date Issued on: & 08.04.2021 \\ [1em] % issuing date
Submitted on: & xx.yy.zzzz \\ [3em] %date of hand in Submitted on: & 01.08.2021 \\ [3em] %date of hand in
First examiner: & Prof. Priv.-Doz. Dr. techn. Andreas Riener\\ [1em] First examiner: & Prof. Priv.-Doz. Dr. techn. Andreas Riener\\ [1em]
Second examiner: & Prof. Dr. rer. nat. Franz Regensburger\\[3em] Second examiner: & Prof. Dr. rer. nat. Franz Regensburger\\[3em]

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