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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <article-id pub-id-type="doi">10.1109/TBME.2015.2474131</article-id>
      <title-group>
        <article-title>Estimation of Mathematical Anxiety Using Psycho-Physiological Data</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Andrej Košir</string-name>
          <email>andrej.kosir@fe.uni-lj.si</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Urban Burnik</string-name>
          <email>urban.burnik@fe.uni-lj.si</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Janez Zaletelj</string-name>
          <email>janez.zaletelj@fe.uni-lj.si</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Samo Jean</string-name>
          <email>samo.jean@lucami.fe.uni-lj.si</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Peter Janjušević</string-name>
          <email>peter.janjusevic@scoms-lj.si</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Gregor Strle</string-name>
          <email>gregor.strle@fe.uni-lj.si</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>The Counselling Centre for Children</institution>
          ,
          <addr-line>Adolescents and Parents Ljubljana, Gotska 18, SI-1000 Ljubljana</addr-line>
          ,
          <country country="SI">Slovenia</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>University of Ljubljana, Faculty of Electrical Engineering</institution>
          ,
          <addr-line>Tržaška 25, SI-1000 Ljubljana</addr-line>
          ,
          <country country="SI">Slovenia</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2016</year>
      </pub-date>
      <volume>2016</volume>
      <fpage>797</fpage>
      <lpage>804</lpage>
      <abstract>
        <p>This work addresses the question of how to estimate mathematical anxiety from psycho-physiological data in real-time applicable to primary school pupils. Besides establishing machine learning and statistical learning architecture, the intrusion of wearable sensors and the feasibility of test dataset collection are considered. From the psychological aspect, the framework of mathematical anxiety estimation was established within the CoolKids program. It provides an established and verified program of helping pupils with mathematical anxiety and the instruments to estimate mathematical anxiety without technology. As such it also provides the measurement scenario. Measurement and estimation system architecture and an early-stage research design are given only.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;psycho-physiological signals</kwd>
        <kwd>mathematical anxiety</kwd>
        <kwd>sensors</kwd>
        <kwd>machine learning</kwd>
        <kwd>social signal processing</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        Mathematics anxiety (MA) is described as “a feeling of tension and anxiety that interferes with
the manipulation of numbers and the solving of mathematical problems in a wide variety of
ordinary life and academic situations.” [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ].
      </p>
      <p>
        According to Luttenberger [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ], anxiety disorders are some of the most widespread mental
health issues worldwide involving nearly 17% of the population. MA is spread across all ages.
Studies of the USA population revealed 95% of the population experienced some MA and 17%
experienced high levels of anxiety. We were not able to find reliable data on the situation in
Central Europe or Slovenia.
      </p>
      <p>
        An important finding is that the research showed mathematical anxiety is not necessarily
linked to lower mathematical abilities and can be caused by numerous other factors as pointed
out by Mammarella et. al. [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. Also, according to Luttenberger [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] math anxiety is diferent
from anxieties in other school subjects or general test anxiety.
      </p>
      <p>
        MA framework is a complex one and it interacts with environment-related and person-related
variables. According to Luttenberger [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ], citation ”antecedents of MA may be
environmentrelated and include culture, the characteristics of educational systems, as well as parents’ and
teachers’ attitudes toward math and their students and children. Furthermore, antecedents
of math anxiety may be person related and include aspects such as trait anxiety or gender”.
Furthermore, variables that interact reciprocally with math anxiety are self-eficacy, self-concept,
and motivation. As a consequence, there is a need for the objective measurement of MA in real
time using modern technology.
      </p>
      <p>In this paper, the first step of the mathematical anxiety (MA) measurement and estimation
system is given. We present the study design including the measurement procedure and
mathematical anxiety ground truth determination. A reliable feasibility study is one of the main
goals including sensor intrusion measurement.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Related Work</title>
      <sec id="sec-2-1">
        <title>2.1. Mathematical anxiety</title>
        <p>
          A primary interest of this study is to estimate mathematical anxiety (MA) from real-time
measurement and to obtain ground truth values best available today. Therefore, models of
mathematical anxiety are the first to be examined. There are several models of mathematical
anxiety studied, among them, MA as a personality construct, MA as a cognitive construct, MA
as a sociocultural construct, and MA as a neuro-biological construct as indicated by Mammarella
et. al. [
          <xref ref-type="bibr" rid="ref3">3</xref>
          ]. In principle, the cognitive construct led to a ground truth determination instrument
and procedure, and the neuro-biological construct led to a psycho-psychological measurement
design. Since the ground truth determination instruments and procedures are taken as ready
to go from the Cool Kids program, we focus primarily on psycho-physiological sensors and
signals, and related machine learning procedures applicable to automatically estimate MA in
real-time.
        </p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2. CoolKids program</title>
        <p>
          The Cool Kids Anxiety Management Program has been developed, designed, and established by
Ron Rapee and his colleagues at Macquarie University. It is been running and further developed
since 1993, [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ]. The program consists of 10 sessions running for 10 weeks. Parents and children
(ages 7-17 years) attend sessions to better cope with and manage their child’s anxiety. The
program can be run with individuals or in a group, in a clinical or school setting [
          <xref ref-type="bibr" rid="ref5">5</xref>
          ].
        </p>
        <p>The theoretical basis of the Cool Kids Anxiety Program is derived from Cognitive Behavioural
Therapy (CBT), with a focus on teaching practical skills. There are a number of research and
scientific studies evaluating the eficiency of the program available. The development of the
program followed these studies. Past studies showed that the majority of attendees of the
program show significant improvement. There were indications of improvements in terms of
an increase in school attendance, academic achievement, confidence, and decreases in worry,
shyness, and fear. The many aspect verifications of the program are crucial for our research
since it assures the best available ground truth values of MA entered into statistical analysis
and machine learning procedures.</p>
        <p>
          Slovenian language versions of procedures materials and instruments were developed and
made available by a consortium of four child and adolescent mental health centers (SCOMS
Ljubljana and Maribor and Community Health Centres Ljubljana and Velenje), through funding
by the Ministry of Health of Republic of Slovenia while obtaining Cool Kids license [
          <xref ref-type="bibr" rid="ref6">6</xref>
          ].
        </p>
      </sec>
      <sec id="sec-2-3">
        <title>2.3. Psycho-physiological signals and mathematical anxiety</title>
        <p>Since MA may be afected by any aspect of cognitive processing, we examined promising studies
from a wider area of processes such as fatigue, afect, and emotion.</p>
        <p>
          Physiological signals were used to estimate users’ fatigue [
          <xref ref-type="bibr" rid="ref7">7</xref>
          ][
          <xref ref-type="bibr" rid="ref8">8</xref>
          ]. Estimation of human activity
can be assessed from sensors using data fusion and machine learning [
          <xref ref-type="bibr" rid="ref9">9</xref>
          ]. Activity recognition
using body-mounted sensors utilizing machine learning provides promising results [
          <xref ref-type="bibr" rid="ref10">10</xref>
          ][11].
Afect and emotion detection is well studied in physiological signals analysis [ 12][13][14] also
utilizing heterogeneous multi-modal data using fusion approaches [15].
        </p>
        <p>To the best of our knowledge, no study on MA estimation from psycho-physiological sensors
is available. However, there were studies on the association of psycho-physiological signals
to MA such as heart rate (HR) and electro-dermal activity (EDA), see [16][17][17]. Only low
efect-size associations were found indicating the automatic estimation of MA from these signals
is a dificult task.</p>
      </sec>
      <sec id="sec-2-4">
        <title>2.4. Psycho-physiological sensors, signals and mathematical anxiety</title>
        <p>Since sensors applicable to a given measurement scenario is a major design-deciding factor, we
present psycho-psychological signals grouped by sensors primarily selected in this research.
According to the previous studies’ results, see Subsec. 3.4, we selected three sensors briefly
described below.
2.4.1. Empatica E4
The Empatica E4 bracelet [18] is a state-of-the-art sensor for the real-time measurement of wrist
psycho-psychological signals. Among others, it covers skin electro-dermal activity (EDA), heart
rate, accelerometer, gyroscope, and others. It is important to point out 200 Hz sampling rate
allows for algorithmically separating EDA signal into a phasic and a tonic signal component.</p>
        <sec id="sec-2-4-1">
          <title>2.4.2. Tobii glasses 3</title>
          <p>Tobii pro glasses 3 [19] supports eye tracking, pupil diameter measurement, head acceleration,
and other measurements. The intrusiveness of eye-tracking glasses was reduced considerably
by a novel design. The calibration procedure is not required for each individual measurement.
Also, it allows selecting lenses with a selected diopter. The Samling rate of eye tracking can be
set to 50  or 100  .</p>
        </sec>
        <sec id="sec-2-4-2">
          <title>2.4.3. Edge computing Camera R50</title>
          <p>Edge computing camera R50 [20] was selected to track the pupil’s skeleton in real-time. The
OAK-D baseboard has three on-board cameras which implement stereo and RGB vision, piped
directly into the OAK SoM for depth and AI processing. The data is then output to a host via
USB 3.1 Gen1 (Type-C).</p>
        </sec>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Methodology and proposed solution</title>
      <p>In this section, we provide an outline of the measurement and mathematical anxiety estimation
operation procedure and PC-based application including selected psycho-physiological sensors.</p>
      <sec id="sec-3-1">
        <title>3.1. System architecture</title>
        <sec id="sec-3-1-1">
          <title>3.1.1. System requirements</title>
          <p>System requirements were derived from research goals and research questions mainly directed
toward the feasibility of automatic mathematical anxiety estimation:
1. Measurement device (to which sensors are connected) might not be the same as the device
presenting estimation results in real-time;
2. Near-real-time measurement and anxiety estimation, delays under 1 second are acceptable;
3. Psycho-physiological sensor connection - there is no applicable standard for sensor
connection and a specific solution for each sensor must be provided;
4. Reliability and end-to-end delay: reliability is of crucial importance and will be regularly
verified (see Sec. 3.1.3). End-to-end delay (measurement, processing, MA estimation) is
not critical, a delay of 1 sec. is acceptable.</p>
        </sec>
        <sec id="sec-3-1-2">
          <title>3.1.2. Proposed solution</title>
          <p>Considering also ethical (including GDPR) requirements we decided the architecture system
architecture is based on a client-server architecture built around node.js run-time environment
[21] and real-time database InfluxDB [ 22]. Specifically:
1. Client/server architecture based on node.js run-time environment;
2. User interface must support 1. real-time interaction of a session supervisor, 2. real-time
visualization of measured signals to monitor sensor ”burn-in” period (for instance, the
bracelet for EDA must get to the right temperature), and to make sure the measurement
system is operating properly;
3. Measurement device is Windows PC as it allows the simplest development environment;
4. Measured signals database: we selected the real-time database InfluxDB meeting all
requirements;
5. Candidate sensors are given in Subsection 2.4.</p>
          <p>The resulting architecture is given in Fig 1</p>
          <p>The outline of the operation is the following: First, we run a script that starts up the sensors.
Data from sensors has to be collected and sent to the server database. This is done with the
help of a python program that turns on the sensors and triggers the sensors to start measuring.
It also sends data to the server database. Values that are sent represent sensor measurements
and are written in JSON format. Next, the database receives the JSON strings that contain
sensor measurements. It stores them in a table that contains a timestamp to maintain the
necessary relations between diferent sources. This information is later used to calculate which
values pertain to the measured event. Afterward, the server’s main assignment is to maintain
a connection between the back-end and front-end. It receives client input which determines
the state of the data-gathering process. Based on client input and values from the database it
calculates the level of anxiety. Calculated data is then forwarded to the client side where it is
presented. The connection between the client and server side is a two-way connection. Its job
is to maintain a connection between the two parts. It forwards the state of the data-gathering
process from the client side and forwards calculation results from the server side. Note that
client is responsible for taking user input that defines the state of the data-gathering process
and forwarding it to the server side. It also presents calculated results from the server side.</p>
        </sec>
        <sec id="sec-3-1-3">
          <title>3.1.3. Reliability and end-to-end delay verification</title>
          <p>Reliability verification will be implemented in terms of
1. Regular arrival data points from sensors: are sensors fully functional?
2. Missing data points from sensors: is the proportion of missing values low enough?
3. Correctness of machine-learning algorithms for MA estimation: do we receive correct</p>
          <p>MA estimation results?
According to our experience with similar systems, the wireless connections (WIFi and Bluetooth)
of sensors to the measurement device is the main source of reliability issues. Reliability will be
verified during the usage of the system regularly once per month.</p>
          <p>End-to-end delay will be measured on three diferent test persons through automatic analysis
of system log files. In the verification mode, the system will be logging the following events:
data point arrivals from sensors, each estimation of MA and user interface refresh. All events
will be time-stamped.</p>
        </sec>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Mathematical anxiety measurement scenario</title>
        <p>The measurement scenario is taken from the Cool Kids format. As an established and verified
program, our goal was to modify it as little as possible. The time frame is given by carefully
designed and structured ten sessions each pupil attends. Sessions are one-to-one and supervised
by certificated psychologists.</p>
        <p>
          We plan to measure two out of ten sessions as identified by the field experts. The session
will be upgraded by a standard explanation of the study purpose to the participants and their
parents and sensor mounting. The online measurements and MA estimation results are not
planned to be shown to the participants. For a fair comparison of results, the rest of the Cool
Kids [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] session procedure will remain as unchanged as possible.
        </p>
      </sec>
      <sec id="sec-3-3">
        <title>3.3. Ground truth determination</title>
        <p>
          To label our measured data on real subjects with estimated mathematical anxiety we also lean on
Cool Kids program [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] and its instruments of mathematical anxiety determination. Such labels
are required to equip machine learning testing datasets. Before the session, the participants will
ifll out a short self-report measure of MA (to be decided later between several diferent scales in
consideration at the moment).
        </p>
        <p>During the process of the session, the participant’s (pupil’s) mathematical anxiety is measured
several times using a single-dimensional 10-level anxiety level scale as a pupil self-report. The
participant estimates and reports her anxiety by looking at the graphical representation of the
scale attached to the wall.</p>
        <p>The number of Likert scale levels of MA as a ground truth will be determined according to
the distribution of obtained values on the 10-level scale. The starting point is a 10-level scale.</p>
        <p>After the session, participants will again fill out a short self-report measure of MA (to be
decided later between several diferent scales in consideration at the moment).</p>
      </sec>
      <sec id="sec-3-4">
        <title>3.4. Statistical and machine learning</title>
        <p>To the best of our knowledge, automatic estimation of Mathematical anxiety in real-time from
psycho-physiological signals was not reported yet. However, useful algorithms were reported
and described from likely related estimations including stress and attention estimation.</p>
        <p>Literature review shows machine and statistical learning algorithms are selected and
optimized according to the selected psycho-physiological signals and features extracted from them.
As such, feature extraction is the main challenge of information extraction from physiological
signals [23][24][25][26]. Since measuring the time dynamics of our test participants, we will
pay special attention to time-local features. Signal-specific feature extraction yields the best
results. Regarding EDA, decomposition to tonic and phasic components is of key importance
[27]. Standard feature extraction includes the number of peaks, variability, and spectral-based
features. There are specific feature extraction techniques. Observing EDA at diferent
frequencies is studied in [28]. Authors of [29] focus on time and frequency domain features followed by
information-based feature selection approaches including maximization of mutual information
and input symmetrical relevance. Chaspari et al [30] proposed a multidimensional EDA
fingerprint as a model of efective feature extraction. Authors of [ 31] focus on multi-modal feature
extraction proposing 40 features designed for fear classification but applicable to other tasks.</p>
        <p>Regarding heart signals, authors of [32] propose dimensionality reduction and salient features
approach to ECG signal directly linked to feature selection and machine learning methods.
Ebrahimzadeh propose lime-local features of ECG signal evaluated for sudden cardiac death [33].
Authors of [34] focus on fusion-based feature extraction of ECG signal applicable as general
purpose framework. Van Gent et. al pay special attention to noisy heart rate signals [35] also
providing a Python toolbox. A systematic review of deep learning-based methods is given in
[36] covering 154 research papers. Machine learning techniques are usually linked to specific
signals and their features [37].</p>
        <p>Studies directed into mathematical anxiety estimation are summarised in [16]. As a
framework, the human autonomous response system is described. The most reliable measurement
pointed out was salivary cortisol level which is not applicable in real-time measurement. There
were several studies on hart rate (HR) correlation to MA and one study [17] reported a negative
correlation to the Anxiety Toward Mathematics Scale with low efect size. Other studies did not
ifnd correlations. Regarding Skin conductance (as a part of Electro-dermal activity) one study
found a positive correlation to the Anxiety Toward Mathematics Scale and to the Mathematics
Anxiety Rating Scale [17]. No pupil diameter relations to MA were reported.</p>
        <p>Several Python toolkit are available, we will base our work on Tsfresh [24], PySiology [25],
Neurokit2 [38] and PyHeart [35].</p>
      </sec>
      <sec id="sec-3-5">
        <title>3.5. Analysis of measured data</title>
        <p>The measured psycho-physiological signals will be reprocessed (missing values, outliers etc.),
time-synchronized, and labeled by the MA ground truth. To make machine learning model
evaluation possible, we will extract candidate psycho-physiological signal features and visualize
them. According to the addressed research question, the following data analysis is planned.
1. Which signal features are associated with MA? A one-way ANOVA design will be applied.</p>
        <p>Since signal features are typically not distributed normally, we will use Kruskal-Wallis
ANOVA when necessary.
2. Which statistical model explains most of the MA variability? To test linear and nonlinear
models, we will statistically test the null hypothesis  0 = [ 2 = 0] for each tested model.
 2 stands for the Coeficient of determination.
3. Which machine learning model performs the best classification on MA classes? For practical
application of MA estimation, classification of MA into predefined classes may be more
efective compared to regression models (ad 2.). We will analyze the distribution of ground
truth values of MA, group them into three or more classes, and evaluate ML classification
algorithms using Area Under ROC measure.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Discussion and Conclusion</title>
      <p>The problem of real-time mathematical anxiety (MA) estimation is posed and the outline of the
solution in terms of technology, procedure, and ground truth of MA determination is proposed.
A plan of statistical analysis is also provided. As the research project is in an early stage,
no experimental results on measurements or machine learning algorithms’ performance are
presented.</p>
      <p>Future work includes measurement application implementation and verification (currently in
progress), two-phase measurement of real subjects, selection and adaptation of most efective
machine learning algorithms, and the evaluation of the results. Note that the research is
primarily focused on the feasibility of the automatic MA estimation using sensors. Performance
in terms of reliability and end-to-end delay is scheduled first. Based on a small-scale study of
ifve participants, we will select classic instruments to measure MA later utilized as machine
learning test labels. Experimental results will be presented in the form of a feasibility study in
terms of machine learning and measurement (sensor intrusion included).</p>
      <p>Acknowledgement. This research was supported by the project P2-0246 ICT4QoL - Information
and Communications Technologies for Quality of Life.
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