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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Toward a technological oriented assessment in psychology: A proposal for the use of contactless devices for Heart Rate Variability and facial emotion recognition in psychological diagnosis</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Raffaele Sperandeo</string-name>
          <email>raffaele.sperandeo@gmail.com</email>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Alfonso Davide Di Sarno</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Teresa Longobardi</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Daniela Iennaco</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Lucia Luciana Mosca</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Nelson Mauro Maldonato</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Department of Neuroscience and Reproductive Sciences and Odontostomatology of the University of Naples Federico II</institution>
          ,
          <addr-line>Naples</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Introduction: Beyond the limits of diagnosis</institution>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>SiPGI - Postgraduate School of Integrated Gestalt Psychotherapy, Torre Annunziata</institution>
          ,
          <addr-line>Naples</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Diagnosis is a complex cognitive process that takes shape within an interpersonal relationship. It aims at the evaluation of mental and affective processes that make the patient suffer, through their classification and identification of the mechanisms and psychological factors that originated them. This process can be made more effective thanks to the introduction in the diagnostic context of technological tools, non-intrusive and relatively simple to use for the detection of biomedical parameters. In the first section, this work highlights some of the critical issues related to psychological diagnosis; subsequently the methods of detecting physiological parameters, such as the Heart Rate Variability and facial expressions related to the patient's emotional fluctuations, are described. Finally, the concept of diagnosis will be introduced, assisted by computational methods, aimed at supporting the work of the clinical psychologist in the complex procedure of diagnosis.</p>
      </abstract>
      <kwd-group>
        <kwd>Psychological Diagnosis</kwd>
        <kwd>Heart Rate Variability</kwd>
        <kwd>Emotion Recognition</kwd>
        <kwd>Kinect v2</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        In 2003 APA [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] defined psychological diagnosis as the evaluation of abnormal
behavior and mental and affective processes that are maladaptive and / or a source of
suffering through their classification in a recognized diagnostic system and the
identification of the mechanisms and psychological factors that originated them and
maintain them [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]. Diagnosis is also a cognitive process that takes place within an
interpersonal relationship, which is its basis and influence it. This process allows the
identification of a psychopathology, if it is present, and can provide data necessary for the
structuring of an effective therapeutic plan [
        <xref ref-type="bibr" rid="ref3 ref4 ref5">3, 4, 5</xref>
        ]. In this perspective, the
relation
      </p>
      <p>
        Copyright © 2019 for this paper by its authors. Use permitted under
Creative Commons License Attribution 4.0 International (CC BY 4.0).
ship established between the psychologist who performs the psychological evaluation
and the patient is of fundamental importance. In this paper, after discussing the limits
of current diagnostic models, a computational approach to diagnosis in
psychopathology is presented, which introduces the use of technologies to integrate mental
reagents with objective biomedical parameters [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. Since the results of the Rosenham
experiment in the 1970s [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ], psychiatric diagnoses have been extremely influenced by
the subjectivity of the observer. However, the current nosographies (DSM and
ICD10) have solved this problem by tightening the operative definitions of the
syndromes and have generated nosographies with poor naturalistic adherence [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ]. The
debate is still strong and one of the possibilities presented by scholars for the
definition of naturalistic nosographic criteria that reflect modern knowledge in the
biomedical and neuroscientific fields, emphasize the use of objectivable biomedical
parameters [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ].
      </p>
      <p>
        Without claiming to identify biological markers for mental disorders, the detection
of psychophysiological signals can be clinically very useful [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ].
      </p>
      <p>The signals generated by the activity of the autonomic nervous system are suitable
for integrating the description of the emotional state of the patients.</p>
      <p>
        One of the most significant physiological parameters is the Heart Rate Variability
which is significantly correlated to individual emotional responses [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ].
2
      </p>
    </sec>
    <sec id="sec-2">
      <title>A question of heart: the implication of the Heart Rate</title>
    </sec>
    <sec id="sec-3">
      <title>Variability in cognition and emotion</title>
      <p>
        The term "Heart Rate Variability" (HRV) indicates the time difference between
two sequential heart beats. It is also called R-R variability since it is given by the
measurement of the interval of two peaks "R" in the reading of the QSR complex of
an electrocardiographic trace. Physiological, cognitive and affective events of
different nature can cause HRV fluctuations. HRV is controlled by the autonomic nervous
system. As is known, the latter consists substantially in the parasympathetic system,
active when low levels of arousal are present (eg. rest, digestion) and in the
sympathetic nervous system, conversely active when elevations of the arousal state are
present, for example in stress conditions. The parasympathetic system decreases the
heart rate, increasing HRV, the sympathetic system increases the heart rate by
decreasing the HRV. This type of mechanics necessarily also involves arousal
fluctuations related to changes in the emotional state: low activation states, and therefore a
high HRV, seems to be related to a condition of substantial well-being, whereas,
instead, it is shown that in different psychopathological conditions such as anxiety[
        <xref ref-type="bibr" rid="ref12">12</xref>
        ],
depression [
        <xref ref-type="bibr" rid="ref13 ref14">13, 14</xref>
        ], bipolar disorder [
        <xref ref-type="bibr" rid="ref15 ref16">15, 16</xref>
        ], phobic manifestations [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ] and panic
disorder [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] there is a fall in HRV. This makes it possible to define this value as an
index of individual self-regulatory abilities [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ]. Therefore, the HRV indicates the
health state of the autonomic nervous system, as a high HRV is associated with
greater flexibility of physiological processes and the production of adaptive responses to
environmental stimuli and changes, inversely to what happens to individuals with low
HRV [
        <xref ref-type="bibr" rid="ref20 ref21">20, 21</xref>
        ].
      </p>
      <p>The need to switch from "contact" to "contactless</p>
      <p>
        The HRV can be measured by a high number of sensors of various degrees of
complexity. The golden standard in HRV measurement is the electrocardiogram
(ECG), which, although it is an effective and accurate detection, at the same time
implies the use of a complex device directly connected to the subject's skin,
potentially inconvenient and intrusive. In fact, a traditional ECG system requires that at least
three bioelectrodes are positioned in different parts of the body to obtain an effective
detection, significantly limiting the patient's mobility, making it inapplicable in
psychopathological assessments [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ]. This resulted in the need to implement equipment
that could detect the heart rate in a non-intrusive manner, as an alternative to the
ECG, such as less intrusive devices such as smartwatch or Heart rate chest strap [
        <xref ref-type="bibr" rid="ref23">23</xref>
        ]
which, however, introduce a foreign element in the interaction between the patient
and the psychodiagnostic. In order to eliminate any element of disturbance in data
collection a series of methodologies have been developed; they are based on small
changes in the color of the skin of the face, invisible to the human eye but visible
through digital devices. Methods based on the photoplethysmographic(PPG) approach
[
        <xref ref-type="bibr" rid="ref24 ref25 ref26">24, 25, 26</xref>
        ] are described in the literature, they allow to identify microvascular blood
volume changes in tissues, through the micro variations of the cutaneous absorption
of light [
        <xref ref-type="bibr" rid="ref27">27</xref>
        ], which is proportional to the variation of blood flow [
        <xref ref-type="bibr" rid="ref28">28</xref>
        ]. PPG
technology has the advantages of being relatively simple as it is composed of a light source
and a photodetector, comfortable for the patient and economically sustainable [
        <xref ref-type="bibr" rid="ref29">29</xref>
        ].
The PPG approach was implemented by other authors [
        <xref ref-type="bibr" rid="ref30">30</xref>
        ] through the Eulerian
Video Magnification (EVM)[
        <xref ref-type="bibr" rid="ref31">31</xref>
        ], introduced to amplify the imperceptible variations in
skin color. The EVM amplifies the color in a video sequence and deconstructs it in
different temporal space bands by detecting the color change of the skin over time
[
        <xref ref-type="bibr" rid="ref32">32</xref>
        ]. Gambi et al [
        <xref ref-type="bibr" rid="ref30">30</xref>
        ] propose using frames of a human face obtained from the input
of a Kinect V2 as a RedGreenBlue(RGB) camera processing the area of the face
through the EVM algorithm. Through a process of extraction of ROI (Region of
interest), they limit the detection to the face and neck areas, so the Fast Fourier Transform
algorithm is applied to the video signal, which converts the data collected into a
collection of coefficients of a combination linear of sinusoids. The variations of the
frequency of the sinusoidal curves allow to obtain as output the HRV [
        <xref ref-type="bibr" rid="ref33">33</xref>
        ]. Tools such as
Kinect v2 was chosen because a single contactless device makes available a series of
additional data such as the analysis of the subject's movements or facial expressions,
detectable simultaneously with the images of the RGB camera. The Kinect v2, was
built in 2014 by Microsoft, and is composed of two cameras, RGB and Infra Red (IR),
allowing to obtain different information streams such as: stream of 2D color image
frames, a stream of 3D depth image frames. These features allow it to function as a
valid depth sensor. Through the Software Development Kit (SDK) [
        <xref ref-type="bibr" rid="ref34">34</xref>
        ], made
available by the manufacturer, it provides a skeleton tracker that gives a stable tracking of
the individual, providing 3D information on the position of 25 joints per person
allowing the detection and recognition of complex movements [
        <xref ref-type="bibr" rid="ref35 ref36">35, 36</xref>
        ]. These methods
are not without criticality, as pointed out by Wang et al.[
        <xref ref-type="bibr" rid="ref37">37</xref>
        ], which show that subtle
color changes or head movements may not be recorded during detection or due to
camera distortions or changes in light conditions, an avoidable eventuality through a
rigorous control of the setting in which this methodology is applied.
3
      </p>
    </sec>
    <sec id="sec-4">
      <title>Beyond HRV: towards an integrated diagnosis</title>
      <p>In view of the functional integration of data to psychological diagnosis, it is
extremely important not only to detect the physiological change of emotion or the
patience’s experience, but also how this is expressed. Humans use different signals to
express emotions, such as facial expressions, gesticulation and voice.</p>
      <p>
        It is known that non-verbal aspects give the most of the information. It has been
estimated that the expression of emotions is conveyed through facial expressions for at
least 55% of the communication, while 7% is instead attributed to the expression
through verbal language [
        <xref ref-type="bibr" rid="ref38">38</xref>
        ]. Seven basic human emotions are commonly
recognized: joy, surprise, anger, sadness, fear, disgust and neutral; the recognition
procedure of an emotional experience is extremely complex, above all because different
emotional expressions share some salient expressive characteristics and an observer
could recognize the emotion but not be able to identify the different nuances of that
experience with clarity: for example a sad smile or a fear caused by disgust[
        <xref ref-type="bibr" rid="ref39">39</xref>
        ]. The
researchers relied on different theoretical approaches to apply technological
methodologies to the recognition of emotions. Therefore, some studies was been inspired by
the detailed work developed by Ekman, the Facial Action Coding System
(FACS)[
        <xref ref-type="bibr" rid="ref40">40</xref>
        ], a system based on the change of facial muscles characteristic of the
individual expression of human emotions. This system has coded the movement of
specific facial muscles called "Action Units" (AU), which reflect the continuous changes
in facial expressions. Based on Ekman's studies, over 46 fundamental AUs, producing
the facial expressions of emotions, have been codified [
        <xref ref-type="bibr" rid="ref41">41</xref>
        ]. Kinect face tracking is
based on Active Appearance Model (AAM), one of the most popular methods for
pattern recognition applied to deformable objects. It is an algorithm for matching the
statistical model of the shape and appearance of the object to a new image, widely
used in the localization of the features of the faces [
        <xref ref-type="bibr" rid="ref42">42</xref>
        ]. Although some authors
consider it desirable to use different sensors for an effective expressive-emotional
recognition, this method was implemented through the use of depths and RGB data of the
Kinect camera [
        <xref ref-type="bibr" rid="ref43">43</xref>
        ]. Several studies have revealed the effectiveness of using Kinect in
facial expression recognition [
        <xref ref-type="bibr" rid="ref44 ref45 ref46">44, 45, 46</xref>
        ].
4
      </p>
    </sec>
    <sec id="sec-5">
      <title>Conclusions</title>
      <p>Psychological diagnosis is a complex interactive relational process of fundamental
importance for the preparation and management of the patient's therapeutic plan and
also an important indication of the relational modalities that the therapist can follow
during the treatment.</p>
      <p>
        This complex relationship can be enriched by the introduction in the diagnostic
context of technological tools, non-intrusive, economic and relatively simple to use
for the detection of fundamental biomedical parameters. The detection of both the
HRV and the expression of emotions through facial expression can be essential to
obtain the most reliable and objectable psychological assessment model possible. For
a near future we mean to conceive differently the psychopathological diagnosis,
basing it on new neuro-psychophysiological discoveries and introducing a diagnostic
standard based on computational methods in order to support the work of the clinical
psychologist in the complex definition of the treatment protocol [
        <xref ref-type="bibr" rid="ref47">47</xref>
        ].
      </p>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          1.
          <string-name>
            <surname>APA (American</surname>
            <given-names>PsychologicalAssociation)</given-names>
          </string-name>
          ,
          <source>Parere sulla diagnosi</source>
          .
          <year>2003</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          2.
          <string-name>
            <surname>Sperandeo</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Esposito</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Maldonato</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Dell'Orco</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          (
          <year>2015</year>
          , May).
          <article-title>Analyzing correlations between personality disorders and frontal functions: a pilot study</article-title>
          .
          <source>In International Workshop on Neural Networks</source>
          (pp.
          <fpage>293</fpage>
          -
          <lpage>302</lpage>
          ). Springer, Cham.
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          3.
          <string-name>
            <surname>Cantone</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Sperandeo</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Maldonato</surname>
            ,
            <given-names>M. N.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Cozzolino</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Perris</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          (
          <year>2012</year>
          ).
          <article-title>Dissociative phenomena in a sample of outpatients</article-title>
          .
          <source>Rivista di psichiatria</source>
          ,
          <volume>47</volume>
          (
          <issue>3</issue>
          ),
          <fpage>246</fpage>
          -
          <lpage>253</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          4.
          <string-name>
            <surname>Maldonato</surname>
            ,
            <given-names>N. M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Sperandeo</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Moretto</surname>
            ,
            <given-names>E.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Dell'Orco</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          (
          <year>2018</year>
          ).
          <article-title>A non-linear predictive model of borderline personality disorder based on multilayer perceptron</article-title>
          . Frontiers in psychology,
          <volume>9</volume>
          ,
          <fpage>447</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          5.
          <string-name>
            <surname>Dazzi</surname>
            ,
            <given-names>N.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Lingiardi</surname>
            ,
            <given-names>V.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Gazzillo</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <article-title>La diagnosi in psicologia clinica</article-title>
          . Personalità e psicopatologia, Milano, Raffaello Cortina,
          <year>2014</year>
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          6.
          <string-name>
            <surname>Repetto</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Serino</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Maldonato</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Longobardi</surname>
            ,
            <given-names>T.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Sperandeo</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Iennaco</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Riva</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          (
          <year>2019</year>
          , April).
          <article-title>Immersive Episodic Memory Assessment with 360° Videos: The Protocol and a Case Study</article-title>
          .
          <source>In International Symposium on Pervasive Computing Paradigms for Mental Health</source>
          (pp.
          <fpage>117</fpage>
          -
          <lpage>128</lpage>
          ). Springer, Cham.
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          7.
          <string-name>
            <surname>Rosenhan</surname>
            ,
            <given-names>D. L.</given-names>
          </string-name>
          ,
          <article-title>On being sane in insane places</article-title>
          .
          <source>Science</source>
          .
          <year>1973</year>
          ;
          <volume>179</volume>
          :
          <fpage>250</fpage>
          -
          <lpage>258</lpage>
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          8.
          <string-name>
            <surname>Sperandeo</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Maldonato</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Moretto</surname>
            ,
            <given-names>E.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Dell'Orco</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          (
          <year>2019</year>
          ).
          <article-title>Executive Functions and Personality from a Systemic-Ecological Perspective</article-title>
          .
          <source>In Cognitive Infocommunications, Theory and Applications</source>
          (pp.
          <fpage>79</fpage>
          -
          <lpage>90</lpage>
          ). Springer, Cham.
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          9.
          <string-name>
            <surname>Double</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          (
          <year>2002</year>
          ).
          <article-title>The limits of psychiatry</article-title>
          .
          <source>Bmj</source>
          ,
          <volume>324</volume>
          (
          <issue>7342</issue>
          ),
          <fpage>900</fpage>
          -
          <lpage>904</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          10.
          <string-name>
            <surname>Krystal</surname>
            ,
            <given-names>J. H.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>State</surname>
            ,
            <given-names>M. W.</given-names>
          </string-name>
          (
          <year>2014</year>
          ).
          <article-title>Psychiatric disorders: diagnosis to therapy</article-title>
          .
          <source>Cell</source>
          ,
          <volume>157</volume>
          (
          <issue>1</issue>
          ),
          <fpage>201</fpage>
          -
          <lpage>214</lpage>
          . doi:
          <volume>10</volume>
          .1016/j.cell.
          <year>2014</year>
          .
          <volume>02</volume>
          .042
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          11.
          <string-name>
            <surname>Williams</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Cash</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Rankin</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Bernardi</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Koenig</surname>
            ,
            <given-names>J.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Thayer</surname>
            ,
            <given-names>J.</given-names>
          </string-name>
          (
          <year>2015</year>
          ).
          <article-title>Resting heart rate variability predicts self-reported difficulties in emotion regulation: a focus on different facets of emotion regulation</article-title>
          . Frontiers In Psychology,
          <volume>6</volume>
          . doi:
          <volume>10</volume>
          .3389/fpsyg.
          <year>2015</year>
          .00261
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          12.
          <string-name>
            <surname>Gorman</surname>
            ,
            <given-names>J. M.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Sloan</surname>
            ,
            <given-names>R. P.</given-names>
          </string-name>
          (
          <year>2000</year>
          ).
          <article-title>Heart rate variability in depressive and anxiety disorders</article-title>
          .
          <source>American Heart Journal</source>
          ,
          <volume>140</volume>
          (
          <issue>4</issue>
          ),
          <fpage>S77</fpage>
          -
          <lpage>S83</lpage>
          . doi:
          <volume>10</volume>
          .1067/mhj.
          <year>2000</year>
          .109981
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>
          13.
          <string-name>
            <surname>Kidwell</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Ellenbroek</surname>
            ,
            <given-names>B. A.</given-names>
          </string-name>
          (
          <year>2018</year>
          ).
          <article-title>Heart and soul: heart rate variability and major depression</article-title>
          .
          <source>Behavioural pharmacology</source>
          ,
          <volume>29</volume>
          (
          <issue>2</issue>
          ),
          <fpage>152</fpage>
          -
          <lpage>164</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref14">
        <mixed-citation>
          14.
          <string-name>
            <surname>Dominique</surname>
            ,
            <given-names>L.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Musselman</surname>
            ,
            <given-names>D. L.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Charles</surname>
            ,
            <given-names>B. N.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Nemeroff</surname>
            ,
            <given-names>C. B.</given-names>
          </string-name>
          (
          <year>1998</year>
          ).
          <article-title>The relationship of depression to cardiovascular disease</article-title>
          .
          <source>Arch Gen Psychiatric</source>
          ,
          <volume>55</volume>
          ,
          <fpage>580</fpage>
          -
          <lpage>592</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref15">
        <mixed-citation>
          15.
          <string-name>
            <surname>Chang</surname>
            ,
            <given-names>H. A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Chang</surname>
            ,
            <given-names>C. C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Kuo</surname>
            ,
            <given-names>T. B.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Huang</surname>
            ,
            <given-names>S. Y.</given-names>
          </string-name>
          (
          <year>2015</year>
          ).
          <article-title>Distinguishing bipolar II depression from unipolar major depressive disorder: Differences in heart rate variability</article-title>
          .
          <source>The World Journal of Biological Psychiatry</source>
          ,
          <volume>16</volume>
          (
          <issue>5</issue>
          ),
          <fpage>351</fpage>
          -
          <lpage>360</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref16">
        <mixed-citation>
          16.
          <string-name>
            <surname>Voggt</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Berger</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Obermeier</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Löw</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Seemueller</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Riedel</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          , ... &amp;
          <string-name>
            <surname>Severus</surname>
            ,
            <given-names>E.</given-names>
          </string-name>
          (
          <year>2015</year>
          ).
          <article-title>Heart rate variability and Omega-3 Index in euthymicpatients with bipolardisorders</article-title>
          .
          <source>EuropeanPsychiatry</source>
          ,
          <volume>30</volume>
          (
          <issue>2</issue>
          ),
          <fpage>228</fpage>
          -
          <lpage>232</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref17">
        <mixed-citation>
          17.
          <string-name>
            <surname>Kawachi</surname>
            ,
            <given-names>I.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Sparrow</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Vokonas</surname>
            ,
            <given-names>P. S.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Weiss</surname>
            ,
            <given-names>S. T.</given-names>
          </string-name>
          (
          <year>1995</year>
          ).
          <article-title>Decreased heart rate variability in men with phobic anxiety (data from the Normative Aging Study)</article-title>
          .
          <source>The American journal of cardiology</source>
          ,
          <volume>75</volume>
          (
          <issue>14</issue>
          ),
          <fpage>882</fpage>
          -
          <lpage>885</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref18">
        <mixed-citation>
          18.
          <string-name>
            <surname>Klein</surname>
            ,
            <given-names>E.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Cnaani</surname>
            ,
            <given-names>E.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Harel</surname>
            ,
            <given-names>T.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Braun</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Ben-Haim</surname>
            ,
            <given-names>S. A.</given-names>
          </string-name>
          (
          <year>1995</year>
          ).
          <article-title>Alteredheart rate variability in panicdisorderpatients</article-title>
          .
          <source>Biologicalpsychiatry</source>
          ,
          <volume>37</volume>
          (
          <issue>1</issue>
          ),
          <fpage>18</fpage>
          -
          <lpage>24</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref19">
        <mixed-citation>
          19.
          <string-name>
            <surname>Segerstrom</surname>
            ,
            <given-names>S. C.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Nes</surname>
            ,
            <given-names>L. S.</given-names>
          </string-name>
          (
          <year>2007</year>
          ).
          <article-title>Heart rate variability reflects self-regulatory strength, effort, and fatigue</article-title>
          .
          <source>Psychological science</source>
          ,
          <volume>18</volume>
          (
          <issue>3</issue>
          ),
          <fpage>275</fpage>
          -
          <lpage>281</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref20">
        <mixed-citation>
          20.
          <string-name>
            <surname>Meerwijk</surname>
            ,
            <given-names>E. L.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Chelsa</surname>
            ,
            <given-names>C. A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Weiss</surname>
            ,
            <given-names>S. J.</given-names>
          </string-name>
          (
          <year>2014</year>
          ).
          <article-title>Psychological pain and reduction resting-state heart rate variability in adults with a history of depression</article-title>
          .
          <source>Psychophysiology51 247-256</source>
          .
          <fpage>10</fpage>
          .1111/psyp.12175
        </mixed-citation>
      </ref>
      <ref id="ref21">
        <mixed-citation>
          21.
          <string-name>
            <surname>Haiblum-Itskovitch</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          , Czamanski-Cohen,
          <string-name>
            <given-names>J.</given-names>
            , &amp;
            <surname>Galili</surname>
          </string-name>
          ,
          <string-name>
            <surname>G.</surname>
          </string-name>
          (
          <year>2018</year>
          ).
          <article-title>Emotional response and changes in heart rate variability following art-making with three different art materials</article-title>
          .
          <source>Frontiers in psychology, 9.</source>
        </mixed-citation>
      </ref>
      <ref id="ref22">
        <mixed-citation>
          22.
          <string-name>
            <surname>Zhang</surname>
            ,
            <given-names>Z.</given-names>
          </string-name>
          ,
          <article-title>Photoplethysmography-based heart rate monitoring in physical activities via joint sparse spectrum reconstruction</article-title>
          .
          <source>IEEE Trans Biomed Eng</source>
          <year>2015</year>
          ;
          <volume>62</volume>
          (
          <issue>8</issue>
          ):
          <fpage>1902</fpage>
          -
          <lpage>1910</lpage>
        </mixed-citation>
      </ref>
      <ref id="ref23">
        <mixed-citation>
          23.
          <string-name>
            <surname>Sartor</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Gelissen</surname>
            , J., van Dinther,
            <given-names>R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Roovers</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Papini</surname>
            ,
            <given-names>G. B.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Coppola</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          (
          <year>2018</year>
          ).
          <article-title>Wrist-worn optical and chest strap heart rate comparison in a heterogeneous sample of healthy individuals and in coronary artery disease patients</article-title>
          .
          <source>BMC sports science, medicine &amp; rehabilitation, 10</source>
          , 10. doi:
          <volume>10</volume>
          .1186/s13102-018-0098-0
        </mixed-citation>
      </ref>
      <ref id="ref24">
        <mixed-citation>
          24.
          <string-name>
            <surname>Verkruysse</surname>
            ,
            <given-names>W.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Svaasand</surname>
            ,
            <given-names>L.O.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Nelson</surname>
            ,
            <given-names>J.S.</given-names>
          </string-name>
          <article-title>Remote plethysmographic imaging using ambient light</article-title>
          .
          <source>Opt. Express</source>
          .
          <year>2008</year>
          ;
          <volume>16</volume>
          :
          <fpage>21434</fpage>
          -
          <lpage>21445</lpage>
        </mixed-citation>
      </ref>
      <ref id="ref25">
        <mixed-citation>
          25.
          <string-name>
            <surname>Benezeth</surname>
            ,
            <given-names>Y.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Li</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Macwan</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Nakamura</surname>
            ,
            <given-names>K.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Gomez</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Yang</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          (
          <year>2018</year>
          , March).
          <article-title>Remote heart rate variability for emotional state monitoring</article-title>
          .
          <source>In 2018 IEEE EMBS International Conference on Biomedical &amp; Health Informatics (BHI)</source>
          (pp.
          <fpage>153</fpage>
          -
          <lpage>156</lpage>
          ). IEEE.
        </mixed-citation>
      </ref>
      <ref id="ref26">
        <mixed-citation>
          26.
          <string-name>
            <surname>Tulyakov</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Alameda-Pineda</surname>
            ,
            <given-names>X.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Ricci</surname>
            ,
            <given-names>E.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Yin</surname>
            ,
            <given-names>L.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Cohn</surname>
            ,
            <given-names>J.F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Sebe</surname>
            ,
            <given-names>N.</given-names>
          </string-name>
          ,
          <article-title>Self-Adaptive Matrix Completion for Heart Rate Estimation From Face Videos Under Realistic Conditions; Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition (CVPR); Seattle</article-title>
          , WA, USA.
          <fpage>27</fpage>
          -
          <lpage>30</lpage>
          June 2016
        </mixed-citation>
      </ref>
      <ref id="ref27">
        <mixed-citation>
          27.
          <string-name>
            <surname>Saquib</surname>
            ,
            <given-names>N.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Papon</surname>
            ,
            <given-names>M. T. I.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Ahmad</surname>
            ,
            <given-names>I.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Rahman</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          (
          <year>2015</year>
          , January).
          <article-title>Measurement of heart rate using photoplethysmography</article-title>
          .
          <source>In 2015 International Conference on Networking Systems and Security (NSysS)</source>
          (pp.
          <fpage>1</fpage>
          -
          <lpage>6</lpage>
          ). IEEE.
        </mixed-citation>
      </ref>
      <ref id="ref28">
        <mixed-citation>
          28.
          <string-name>
            <surname>Wang</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Li</surname>
            ,
            <given-names>Z.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Wei</surname>
            ,
            <given-names>X.</given-names>
          </string-name>
          ,
          <article-title>Monitoring heart and respiratory rates at radial artery based on PPG</article-title>
          .
          <source>Opt Int J Light Electron Opt</source>
          <year>2013</year>
          ;
          <volume>124</volume>
          (
          <issue>4</issue>
          ):
          <fpage>3954</fpage>
          -
          <lpage>3956</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref29">
        <mixed-citation>
          29.
          <string-name>
            <surname>Sviridova</surname>
            ,
            <given-names>N.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Sakai</surname>
            ,
            <given-names>K.</given-names>
          </string-name>
          ,
          <article-title>Human photoplethysmogram: new insight into chaotic characteristics</article-title>
          .
          <source>Chaos Solitons &amp; Fractals</source>
          .
          <year>2015</year>
          ;
          <volume>77</volume>
          :
          <fpage>53</fpage>
          -
          <lpage>63</lpage>
        </mixed-citation>
      </ref>
      <ref id="ref30">
        <mixed-citation>
          30.
          <string-name>
            <surname>Gambi</surname>
            ,
            <given-names>E.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Agostinelli</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Belli</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Burattini</surname>
            ,
            <given-names>L.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Cippitelli</surname>
            ,
            <given-names>E.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Fioretti</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          , ...
          <string-name>
            <surname>Spinsante</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          (
          <year>2017</year>
          ).
          <article-title>Heart Rate Detection Using Microsoft Kinect: Validation and Comparison to Wearable Devices</article-title>
          .
          <source>Sensors</source>
          (Basel, Switzerland),
          <volume>17</volume>
          (
          <issue>8</issue>
          ), 1776. doi:
          <volume>10</volume>
          .3390/s17081776
        </mixed-citation>
      </ref>
      <ref id="ref31">
        <mixed-citation>
          31.
          <string-name>
            <surname>Wu</surname>
          </string-name>
          , H. Y.,
          <string-name>
            <surname>Rubinstein</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Shih</surname>
            ,
            <given-names>E.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Guttag</surname>
            ,
            <given-names>J.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Durand</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Freeman</surname>
            ,
            <given-names>W.</given-names>
          </string-name>
          (
          <year>2012</year>
          ).
          <article-title>Eulerian video magnification for revealing subtle changes in the world</article-title>
          .
        </mixed-citation>
      </ref>
      <ref id="ref32">
        <mixed-citation>
          32.
          <string-name>
            <surname>Liu</surname>
            ,
            <given-names>Y. F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Vuong</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Walker</surname>
            ,
            <given-names>P. C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Peterson</surname>
            ,
            <given-names>N. R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Inman</surname>
            ,
            <given-names>J. C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Filho</surname>
            ,
            <given-names>P. A.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Lee</surname>
            ,
            <given-names>S. C.</given-names>
          </string-name>
          (
          <year>2016</year>
          ).
          <article-title>Noninvasive Free Flap Monitoring Using Eulerian Video Magnification</article-title>
          .
          <source>Case reports in otolaryngology,</source>
          <year>2016</year>
          ,
          <volume>9471696</volume>
          . doi:
          <volume>10</volume>
          .1155/
          <year>2016</year>
          /9471696
        </mixed-citation>
      </ref>
      <ref id="ref33">
        <mixed-citation>
          33.
          <string-name>
            <surname>Al-Naji</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Gibson</surname>
            ,
            <given-names>K.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Chahl</surname>
            ,
            <given-names>J.</given-names>
          </string-name>
          (
          <year>2017</year>
          ).
          <article-title>Remote sensing of physiological signs using a machine vision system</article-title>
          .
          <source>Journal of medical engineering &amp; technology, 41(5)</source>
          ,
          <fpage>396</fpage>
          -
          <lpage>405</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref34">
        <mixed-citation>
          34.
          <string-name>
            <surname>Microsoft</surname>
            <given-names>Corporation</given-names>
          </string-name>
          ,
          <article-title>Kinect for windows SDK programming guide</article-title>
          ,
          <source>version 1.5</source>
          ,
          <year>2012</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref35">
        <mixed-citation>
          35.
          <string-name>
            <surname>Giancola</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Corti</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Molteni</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Sala</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          (
          <year>2016</year>
          , November).
          <article-title>Motion capture: an evaluation of kinect V2 body tracking for upper limb motion analysis</article-title>
          .
          <source>In International Conference on Wireless Mobile Communication and Healthcare</source>
          (pp.
          <fpage>302</fpage>
          -
          <lpage>309</lpage>
          ). Springer, Cham.
        </mixed-citation>
      </ref>
      <ref id="ref36">
        <mixed-citation>
          36.
          <string-name>
            <surname>Hwang</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Tsai</surname>
            ,
            <given-names>C. Y.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Koontz</surname>
            ,
            <given-names>A. M.</given-names>
          </string-name>
          (
          <year>2017</year>
          ).
          <article-title>Feasibility study of using a Microsoft Kinect for virtual coaching of wheelchair transfer techniques</article-title>
          . Biomedical Engineering/BiomedizinischeTechnik,
          <volume>62</volume>
          (
          <issue>3</issue>
          ),
          <fpage>307</fpage>
          -
          <lpage>313</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref37">
        <mixed-citation>
          37.
          <string-name>
            <surname>Wang</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Pun</surname>
            ,
            <given-names>T.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Chanel</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          (
          <year>2018</year>
          ).
          <article-title>A Comparative Survey of Methods for Remote Heart Rate Detection From Frontal Face Videos</article-title>
          .
          <source>Frontiers in bioengineering and biotechnology</source>
          ,
          <volume>6</volume>
          , 33. doi:
          <volume>10</volume>
          .3389/fbioe.
          <year>2018</year>
          .00033
        </mixed-citation>
      </ref>
      <ref id="ref38">
        <mixed-citation>
          38.
          <string-name>
            <surname>Mehrabian</surname>
            <given-names>A</given-names>
          </string-name>
          .
          <article-title>Communication without words</article-title>
          .
          <source>IOJT</source>
          .
          <year>2008</year>
          :
          <fpage>193</fpage>
          -
          <lpage>200</lpage>
        </mixed-citation>
      </ref>
      <ref id="ref39">
        <mixed-citation>
          39.
          <string-name>
            <surname>Alabbasi</surname>
            ,
            <given-names>H. A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Moldoveanu</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Moldoveanu</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          (
          <year>2015</year>
          ).
          <article-title>Real time facial emotion recognition using kinect V2 sensor</article-title>
          .
          <source>IOSR J. Comput. Eng. Ver</source>
          . II,
          <volume>17</volume>
          (
          <issue>3</issue>
          ),
          <fpage>2278</fpage>
          -
          <lpage>2661</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref40">
        <mixed-citation>
          40.
          <string-name>
            <surname>Ekman</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          (
          <year>1997</year>
          ).
          <article-title>What the face reveals: Basic and applied studies of spontaneous expression using the Facial Action Coding System (FACS)</article-title>
          . Oxford University Press, USA.
        </mixed-citation>
      </ref>
      <ref id="ref41">
        <mixed-citation>
          41.
          <string-name>
            <surname>Du</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Tao</surname>
            ,
            <given-names>Y.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Martinez</surname>
            ,
            <given-names>A. M.</given-names>
          </string-name>
          (
          <year>2014</year>
          ).
          <article-title>Compound facial expressions of emotion</article-title>
          .
          <source>Proceedings of the National Academy of Sciences of the United States of America</source>
          ,
          <volume>111</volume>
          (
          <issue>15</issue>
          ),
          <fpage>E1454</fpage>
          -
          <lpage>E1462</lpage>
          . doi:
          <volume>10</volume>
          .1073/pnas.1322355111
        </mixed-citation>
      </ref>
      <ref id="ref42">
        <mixed-citation>
          42.
          <string-name>
            <surname>Coots</surname>
            ,
            <given-names>T. F.</given-names>
          </string-name>
          ,
          <string-name>
            <given-names>G. J.</given-names>
            <surname>Edwards</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C. J.</given-names>
            <surname>Taylor</surname>
          </string-name>
          . Active Appearance Models.
          <source>- IEEE Transactions on Pattern Analysis and Machine Intelligence</source>
          , Vol.
          <volume>23</volume>
          ,
          <year>2001</year>
          , No 6, pp.
          <fpage>484</fpage>
          -
          <lpage>498</lpage>
          .
          <fpage>43</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref43">
        <mixed-citation>
          43.
          <string-name>
            <surname>Wang</surname>
            ,
            <given-names>Q.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Yu</surname>
            ,
            <given-names>Y.</given-names>
          </string-name>
          (
          <year>2015</year>
          ).
          <article-title>AAM Based Facial Feature Tracking with Kinect</article-title>
          .
          <source>Cybernetics and Information Technologies</source>
          ,
          <volume>15</volume>
          (
          <issue>3</issue>
          ),
          <fpage>127</fpage>
          -
          <lpage>139</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref44">
        <mixed-citation>
          44.
          <string-name>
            <surname>Gunawan</surname>
            ,
            <given-names>A.A.S.</given-names>
          </string-name>
          ,
          <article-title>Face expression detection on Kinect using active appearance model and fuzzy logic</article-title>
          .
          <source>Procedia Comput. Sci</source>
          .
          <year>2015</year>
          ;
          <volume>59</volume>
          :
          <fpage>268</fpage>
          -
          <lpage>274</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref45">
        <mixed-citation>
          45.
          <string-name>
            <surname>Szwoch</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Pieniążek</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          ,
          <article-title>Facial emotion recognition using depth data;</article-title>
          <source>Proceedings of the 8th International Conference on Human System Interactions; Warsaw</source>
          , Poland.
          <fpage>25</fpage>
          -
          <lpage>27</lpage>
          June 2015; pp.
          <fpage>271</fpage>
          -
          <lpage>277</lpage>
        </mixed-citation>
      </ref>
      <ref id="ref46">
        <mixed-citation>
          46.
          <string-name>
            <surname>Wei</surname>
            ,
            <given-names>W.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Jia</surname>
            ,
            <given-names>Q.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Chen</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          ,
          <article-title>Real-time facial expression recognition for affective computing based on</article-title>
          <source>Kinect; Proceedings of the IEEE 11th Conference on Industrial Electronics and Applications; Hefei, China. 5-7</source>
          June 2016; pp.
          <fpage>161</fpage>
          -
          <lpage>165</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref47">
        <mixed-citation>
          47.
          <string-name>
            <surname>Sperandeo</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Esposito</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Maldonato</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          , &amp;
          <string-name>
            <surname>Dell'Orco</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          (
          <year>2015</year>
          , May).
          <article-title>Analyzing correlations between personality disorders and frontal functions: a pilot study</article-title>
          .
          <source>In International Workshop on Neural Networks</source>
          (pp.
          <fpage>293</fpage>
          -
          <lpage>302</lpage>
          ). Springer, Cham.
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>