@ -2,7 +2,9 @@
% To better understand which metrics and methods are meaningful in the domain of keyboards and especially when
% To investigate whether or not solely the actuation force of individual keys can make a difference in terms of efficiency or satisfaction an ....
\subsection { Keyboards and key switches}
\subsection { Keyboards and Keyswitches}
\subsubsection { Keyboard Models and Layouts}
\label { sec:kb_ layout}
\begin { figure} [ht]
\centering
@ -15,12 +17,12 @@ 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
be seen in Figure \ref { fig:keyboard_ models} . The obvious difference between
those keyboards in Figure \ref { fig:keyboard_ models} is their general
appearance. What we see is mainly the shape of the enclosure and the keycaps,
which are the rectangular pieces of plastic on top of the actual keyswitches
which sometimes indicate which letter, number or symbol, also known as
characters, a keypress should send to the computer. These keycaps are mainly
made out of the two plastics \gls { ABS} and \gls { PBT} which primarily differ in
feel, durability, cost and sound \parencite [8] { bassett_ keycap} .
appearance. The keyboards feature different enclosures and keycaps, which are
the rectangular pieces of plastic on top of the actual keyswitches that
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
two plastics \gls { ABS} and \gls { PBT} which primarily differ in feel, durability,
cost and sound \parencite [8] { bassett_ keycap} .
\begin { figure} [ht]
\centering
@ -31,16 +33,16 @@ feel, durability, cost and sound \parencite[8]{bassett_keycap}.
\label { fig:keyboard_ layouts}
\end { figure}
Nowadays, there are three main standards for the physical layout of keyboards
namely ISO/IEC 9995 \cite { iso9995-2} , ANSI-INCITS 154-1988
\cite { ansi-incits-154-1988} and JIS X 6002-1980 \cite { jis-x-6002-1980} , that
propose slightly different arrangements of the keys and some even alter the
shape of a few keys. Figure TODO \ref { fig:keyboard_ layouts} shows the layouts
defined by the three standards mentioned and shows the main differences. In
addition to the physical layout, there are also various layouts concerning the
mapping of the physical key to a character that is displayed by the
computer. Most of the time, the mapping happens on the computer via software and
therefore the choice of layout is not necessarily restricted by the physical
Nowadays, there are three main standards that define the physical layout of a
keyboard― ISO/IEC 9995 \cite { iso9995-2} , ANSI-INCITS 154-1988
\cite { ansi-incits-154-1988} and JIS X 6002-1980 \cite { jis-x-6002-1980} . These
layouts propose slightly different arrangements of the keys and some even alter
the shape of a few keys entirely . Figure \ref { fig:keyboard_ layouts} shows the
layouts defined by the three standards mentioned and shows the main
differences. In addition to the physical layout, there are also various layouts
concerning the mapping of the physical key to a character that is displayed by
the computer. Most of the time, the mapping happens on the computer via software
and therefore the choice of layout is not necessarily restricted by the physical
layout of the keyboard but rather a personal preference. As seen in Figure
\ref { fig:keyboard_ models} , there are also non standard physical layouts
available which are often designed to improve the posture of the upper extremity
@ -48,28 +50,36 @@ while typing to reduce the risk of injury or even assist in recovering from
previous \gls { WRUED} \cite { ripat_ ergo} . Those designs often split the keyboard
in two halves to reduce ulnar deviation and some designs also allow tenting of
the halves or provide a fixed tent which also reduces forearm pronation
\cite { baker_ ergo, rempel_ ergo} . Besides the exterior design of the keyboard,
there is another part of interest—the keyswitch. This component of a keyboard
actually sends the signal that a key is pressed. There are different types of
keyswitches available to date. The more commonly available ones are scissor
switches and rubber dome switches which are both subsets of the membrane
switches. Scissor switches are often found in keyboards that are integrated into
notebooks while rubber dome switches are mostly used in workplace
keyboards. Both variants use a rubber membrane with small domes underneath each
key. When a key is pressed, the corresponding dome collapses and because the
dome's inner wall is coated with a conductive material, closes an electrical
circuit \cite { ergopedia_ keyswitch, peery_ 3d_ keyswitch} . Another type of switches
are mechanical keyswitches. These switches are frequently used in gaming and
high quality workplace keyboards as well as by enthusiast along with prosumers
which build and then sell custom made keyboards to the latter audience
\cite { bassett_ keycap, ergopedia_ keyswitch} . These keyswitches are composed of
several mechanical parts which can be examined in Figure
\ref { fig:mech_ keyswitches_ dissas} . The housing is made up of two parts, the
bottom and top shell. The actual mechanism consists of two conductive plates,
which when connected trigger a keypress, a stainless steel spring which defines
how much force has to be applied to the switch to activate it and a stem 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
\cite { baker_ ergo, rempel_ ergo} .
\subsubsection { Membrane Keyswitch}
\label { sec:mem_ switch}
Besides the exterior design of the keyboard, there is another part of
interest—the keyswitch. This component of a keyboard actually sends the signal
that a key is pressed. There are different types of keyswitches available to
date. The more commonly available ones are scissor switches and rubber dome
switches which are both subsets of the membrane switches. Scissor switches are
often found in keyboards that are integrated into notebooks while rubber dome
switches are mostly used in workplace keyboards. Both variants use a rubber
membrane with small domes underneath each key. When a key is pressed, the
corresponding dome collapses and because the dome's inner wall is coated with a
conductive material, closes an electrical circuit \cite { ergopedia_ keyswitch,
peery_ 3d_ keyswitch} .
\subsubsection { Mechanical Keyswitch}
\label { sec:mech_ switch}
Another type of switches are mechanical keyswitches. These switches are
frequently used in gaming and high quality workplace keyboards as well as by
enthusiast along with prosumers which build and then sell custom made keyboards
to the latter audience \cite { bassett_ keycap, ergopedia_ keyswitch} . These
keyswitches are composed of several mechanical parts which can be examined in
Figure \ref { fig:mech_ keyswitches_ dissas} . The housing is made up of two parts,
the bottom and top shell. The actual mechanism consists of two conductive
plates, which when connected trigger a keypress, a stainless steel spring which
defines how much force has to be applied to the switch to activate it and a stem
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
\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
stem, the spring gets contracted and the stem moves downwards and thereby stops
@ -154,7 +164,7 @@ typing speed, which could be more significant with greater variation of
actuation force across tested keyboards \cite { loricchio_ force_ speed} .
\subsubsection { Relevance for this t hesis}
\subsubsection { Relevance for this T hesis}
Since this thesis is focused around keyboards and especially the relation
between the actuation force of the keyswitch and efficiency (speed, error rate)
and also the differences in satisfaction while using keyswitches with varying
@ -186,7 +196,7 @@ capabilities for our experiment to reduce the effort required to equip each
keyboard with the required keyswitches and in case a keyswitch fails during
the experiment, decrease the time required to replace the faulty switch.
\subsection { Measurement of typing related m etrics}
\subsection { Measurement of Typing Related M etrics}
\label { sec:metrics}
Nowadays, a common way to compare different methods concerning alphanumeric
input in terms of efficiency is to use one of many typing test or word
@ -195,7 +205,12 @@ software used and the experimental setup, users have to input different kinds of
text, either for a predefined time or the time is measured till the whole text
is transcribed \cite { chen_ typing_ test, hoffmann_ typeright,
fagarasanu_ force_ training, akagi_ keyswitch, kim_ typingforces,
pereira_ typing_ test} . Text used should be easy to read for typists
pereira_ typing_ test} .
\subsubsection { Readability of Text}
\label { sec:meas_ fre}
Text used should be easy to read for typists
participating in studies that evaluate their performance and are therefore is
chosen based on a metric called the \gls { FRE} which indicates the
understandability of text \cite { fagarasanu_ force_ training,
@ -232,6 +247,9 @@ classified according to the ranges given in Table \ref{tbl:fre_ranges} \cite{fle
\end { tabular}
\end { table}
\subsubsection { Performance Metrics}
\label { sec:meas_ perf}
There are several metrics to measure the performance of typists. Typical methods
to measure speed are
\begin { enumerate}
@ -280,6 +298,9 @@ following two methods
\end { equation}
\end { enumerate}
\subsubsection { Electromyography}
\label { sec:meas_ emg}
In several other studies, in addition to the metrics mentioned so far, \gls { EMG}
data was captured to evaluate the muscle activity or applied force while typing
on completely different or modified hardware \cite { kim_ typingforces,
@ -312,29 +333,31 @@ convert applied force to an electrical signal. This signal usually gets
amplified by specialized circuits and then further processed by a micro
controller, computer or other hardware \cite { johnson_ loadcell} .
\subsubsection { Subjective Metrics}
\label { sec:meas_ sub}
Lastly, subjective metrics e.g., comfort, usability, user experience, fatigue
and satisfaction, are evaluated based on survey data collected after
participants used different input methods \cite { kim_ typingforces,
bell_ pauseboard, bufton_ typingforces, pereira_ typing_ test, iso9241-411} . In
their study, Kim et al. used a survey provided by the \gls { ISO} which is
specifically designed to evaluate different keyboards in terms of user
satisfaction, comfort and usability \cite { kim_ typingforces, iso9241-411} . This
survey poses a total of twelve questions concerning e.g., fatigue of specific
regions of the upper extremity, general satisfaction with the keyboard,
perceived precision and uniformity while typing, etc., which are presented on a
seven-point Likert-scale \cite { iso9241-411} . Further, studies concerning the
usability and user experience of different text entry methods used the \gls { UEQ}
or \gls { UEQ-S} to evaluate the differences in those categories \cite { nguyen_ ueq,
olshevsky_ ueq, gkoumas_ ueq} . While the full \gls { UEQ} provides a total of 26
questions divided into six scales (attractiveness, perspicuity, efficiency,
dependability, stimulation and novelty), the \gls { UEQ-S} only features 8
questions and two scales (pragmatic and hedonic quality). Because of the limited
explanatory power of the \gls { UEQ-S} , it is recommended to only use it, if ther e
is not enough time to complete the full \gls { UEQ} or if the participants of a
study are required to rate several products in one session
\cite { schrepp_ ueq_ handbook} .
\subsubsection { Relevance for this t hesis}
their study, Kim et al. used a modified version of the \gls { KCQ} provided by the
\gls { ISO} which is
terms of user satisfaction, comfort and usability \cite { kim_ typingforces,
iso9241-411} . This survey poses a total of twelve questions concerning e.g.,
fatigue of specific regions of the upper extremity, general satisfaction with
the keyboard, perceived precision and uniformity while typing, etc., which are
presented on a seven-point Likert-scale \cite { iso9241-411} . Further, studies
concerning the usability and user experience of different text entry methods
used the \gls { UEQ} or \gls { UEQ-S} to evaluate the differences in those
categories \cite { nguyen_ ueq,_ ueq, gkoumas_ ueq} . While the full
\gls { UEQ} provides a total of 26
(attractiveness, perspicuity, efficiency, dependability, stimulation and
novelty), the \gls { UEQ-S} only features 8 questions and two scales (pragmatic
and hedonic quality). Because of the limited explanatory power of th e
\gls { UEQ-S} , it is recommended to only use it, if there is not enough time to
complete the full \gls { UEQ} or if the participants of a study are required to
rate several products in one session \cite { schrepp_ ueq_ handbook} .
\subsubsection { Relevance for this T hesis}
Measuring metrics related to data entry tasks can be performed with the help
several commercially available tools and equipment. Especially muscle activity
has to be measured with appropriate tools and accurate placement of the
@ -348,38 +371,85 @@ thereby reveal differences that cannot be easily acquired by a device or formula
\cite { rowley_ surveys} .
\subsection { Crowdsourcing / Observer Bias}
As shown by the previous research in Section \ref { sec:metrics} , it is common
practice in research related to typing to present a text that has to be
transcribed by the participant. Usually, the text was chosen by the researcher
or already available through the used typing test software. If the
understandability of text is of concern, the binary choice of, is understandable
or not, made by the researcher could lead to a phenomenon called the observer
bias \cite { hrob_ observer, berger _ observer} . Thus, the text could potentially be
to difficult to understand for the participants if not evaluated with e.g. the
\subsection { Observer Bias and a Possible Solution }
As already discussed in Section \ref { sec:metrics} , it is common practice in
research related to typing to present a text that has to be transcribed by the
participant. Usually, the text was chosen by the researcher or already available
through the used typing test software. If the understandability of text is of
concern, the binary choice of, is understandable or not, made by the researcher
could lead to a phenomenon called the observer bias \cite { hrob_ observer,
berger_ observer, angrosino _ observer} . Thus, the text could potentially be to
difficult to understand for the participants if not evaluated with e.g. the
\gls { FRE} or other adequate formulas. Further, if there is previous knowledge
about the requested participants, the researcher could subconsciously select
text that is familiar to, or well received by some of the subjects and could
thereby conceivably influence the outcome \cite { hrob_ observer, berger_ observer} .
The same problem arises, if the typing test software already provides such texts
but the researcher has to select some of them for the experiment. Further, the
difficulty of the provided texts should be verified to ensure accurate results
across multiple treatments. A possible solution for this problem is
crowdsourcing.
Howe CONTINUE
\cite { howe_ crowdsource} . If there are automated checks for text
difficulty in place, this method completely excludes the researcher from the
text selection process.
\subsubsection { Relevance for this thesis}
% \subsection { Keyboard usage}
% \subsection { Finger strength}
% \subsection { Traditional methods}
% \subsection { Alternative methodology}
% - Available Methods (Impact vs load)
% - Load cells
thereby conceivably influence the outcome of the study\cite { hrob_ observer,
berger_ observer} . The same problem arises, if the typing test software already
provides such texts but the researcher has to select some of them for the
experiment. Furthermore, the difficulty of the provided texts should be verified
to ensure accurate results across multiple treatments. A possible solution to
this problem is crowdsourcing. Howe describes crowdsourcing as the act of
outsourcing a problem to a group of individuals that are voluntarily working
together to solve it \parencite [1-11] { howe_ crowd_ book} \&
\cite { howe_ crowdsource, schenk_ crowdsource} .
Observer bias can also occur while conducting the experiment when the researcher
has to give instructions to the subject. Therefore, it is important to treat
every participant equally by following a predefined procedure and minimize
unnecessary interaction where possible to further minimize the risk of bias
\parencite [674] { angrosino_ observer} .
\subsubsection { Relevance for this Thesis}
Summarizing, even seemingly arbitrary decisions or actions can have a potential
undesirable impact on the results of a study. If it is possible to implement
automated checks for the suitability of text e.g., a platform that verifies
submitted text based on \gls { FRE} scores, crowdsourcing could be used to
completely exclude the researcher from the text selection process and therefore
mitigate the risk of unwanted bias. In addition, the aspect of time in the
preparation phase of a study could be another factor to consider crowdsourcing
to acquire larger amounts of text with equal difficulty.
\subsection { Strength of Individual Fingers}
As already mentioned in Section \ref { sec:metrics} , the force applied to a
keyswitch is the concern of multiple studies that evaluate the relation between
keyboarding and \gls { WRUED} . Further, multiple studies came to the conclusion,
that there is a significant discrepancy in strength between individual fingers
\cite { bretz_ finger, martin_ force, baker_ kinematics, dickson_ finger} . Bretz et
al. found, that when participants squeezed an object between thumb and finger,
differences in applicable force between different fingers ranged from 1.6
\gls { N} up to 25.9 \gls { N} (n=16) \cite { bretz_ finger} . Dickson and Nicolle
observed the effects of surgery on patients with rheumatoid hands. The pre and
post surgery force of finger flexion was recorded and the post surgery results
yielded a difference in flexion force, which is similar to the force required to
actuate a keyswitch, that ranged from 1 \gls { N} to 4 \gls { N}
\cite { dickson_ finger} . Martin et al. measured applied average and peak force of
individual digits while typing on a keyboard (n=10). The measured differences
ranged from 0.10 \gls { N} to 1.49 \gls { N} for peak force and 0.01 \gls { N} to 0.08
\gls { N} for mean force \cite { martin_ force} .
\subsubsection { Relevance for this Thesis}
The goal of this thesis is to evaluate the possible advantages of keyboards with
non-uniform actuation forces. The fairly small difference of only 0.08 \gls { N} in mean
force applied to keyboards recorded by Martin et al. \cite { martin_ force} but
rather big difference in finger strength measured by Bretz et
al. \cite { bretz_ finger} could indicate, that albeit the difference in strength,
all fingers have to apply equal force to generate a keypress because of the
uniform actuation force used in commercially available keyboards.
\subsection { Summary}
Since keyboards are still the most commonly used input method for data entry to
date and so far all efforts to convince the mainstream to move from the
standard, less ergonomic, physical layouts to split keyboards failed, further
alternatives that could be easily implemented into manufacturing processes have
to be explored, to counteract the rising risks for \gls { WRUED} . One factor
related to \gls { WRUED} is the actuation force of the keyswitches
\cite { bufton_ typingforces, rempel_ ergo, rempel_ force,
gerard_ keyswitch} . Especially higher actuation forces have shown to be the
reason for discomfort in the upper extremity. On the other hand, higher
actuation forces also led to lower error rates while typing and therefore
enhance user satisfaction and performance \cite { gerard_ keyswitch} . With the help
of several methods to measure typing relate metrics such as muscle activity
(\gls { EMG} ), error rates (\gls { CER} and \gls { UER} ), typing speed (\gls { WPM} ) and
user satisfaction { \gls { UEQ} and \gls { KCQ} } it is feasible to evaluate possible
alternative input methods to the more traditional keyboard.
phga
4 years ago