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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Using Scanpath Analysis for Performance and Affects Detection in Computer Users</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Piotr Augustyniak</string-name>
          <email>august@agh.edu.pl</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Mirosław Jabłoński</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Eliasz Kańtoch</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Tomasz Kryjak</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Zbigniew Mikrut</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Elżbieta Pociask</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Jaromir Przybyło</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>AGH University of Science and Technology</institution>
          ,
          <addr-line>30 Mickiewicza Ave. 30-059 Kraków</addr-line>
          <country country="PL">Poland</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>In interpersonal relations, interlocutor's emotions may be easily detected by facial and oculomotoric expressions. Several books are devoted to recognition so called body language expressions (e.g. [18]) several others - to avoiding of uncontrolled disclosure of spontaneous affects (e.g. [14]). Since modern information societies come to replace direct relations by computer-mediated communication and virtually all computers capture the face of the user, the idea of automatic emotion recognition becomes one of most important issue of man-machine interaction. Several papers focusing on facial expression were published as far (e.g. [19]), however our interest focuses rather on emotions expressed in the eyetrack [8], [12]. The approach is motivated by two facts: - the eye globe motion response cannot be trained as easily as face movements in order to hide emotions and - the eye motion can be elicited by the displayed content.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>Introduction</title>
    </sec>
    <sec id="sec-2">
      <title>Eyetarcking methods</title>
      <p>
        Four main principles were employed as far to capture the instantaneous
position of the eye: electric, magnetic, optical and visual [23], [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ]. Recording of eye
motion in electronystagmography is based on electric dipole property of the eye
globe and widely used in medical tests. Second method consists in generation of
artificial alternating magnetic field and induction-based localization of a serach
coil, in this case integrated with eye globe, in this field. Since technology does not
allow for fully non-invasive integration, the magnetic method is rarely used out
of leboratory experiments. An interesting practical feature of first two methods
is the measurement of the eye motion not depending on eyelid open or closed
(i.e. in sleep or vestibular nystagmus studies). The optical method bases on
reflection of artificial beam of light, in most cases infrared, either in the eye fundus
(Purkinje reflex), either in the surface (iris border or cornea cap) [17]. The
visual method is based on motion analysis in an image sequence recorded in visible
or infrared light with use of wide range cameras (webcams to high frame-rate
precision sensors) [22]. Two latter methods are non-invasive, however, with some
      </p>
      <p>Rysunek 1. A volunteer observer wearing Ober-2 eyetracking goggles.
exceptions, designed for open eye recordings. They are immune to interferences
of electrophysiological origin, but since the measurement is reliant on ambient
lighting condition, eyetracking systems either assumme stable conditions either
employ algorithms to compensate for variations. These methods are widely used
for studies of perception, interaction or visual conspicuity of the scene [16].</p>
      <p>While reflection-based eyetrackers are uniquely mounted on the observer’s
head, most of visual eyetrackers use stand-alone cameras allowing for distant
and even consciousless recording. This has two practical consequences:
– wearable eyetrackers determine the eyeglobe position in head-related (i.e.
relative) coordinates, allow for mobility during visual tasks, however
transforming data to environment-related coordinates (i.e. absolute) needs
continuous tracking of the head with a seach coil, visual system or navigation,
– stationary eyetrackers determine the eyeglobe position in absolute
coordinates but work in limited space, higher grade systems employ face or marker
tracking algorithm to compensate for head motion either with an auxiliary
camera either using a high resolution sensor.</p>
      <p>The other aspect is the eyetracking speed. In most perceptual studies 50-200
position samples per second are sufficient for accurate eyetracking, what
justifies suitability of consumer-grade cameras to these tasks. Otherwise, studies of
fast eye motion like microsaccades, or interactive applications requiring real time
reaction of the system would benefit from information rate up to 2 ksps.
Detection of affects, described later in this paper will also need a high-speed recording
equipment, since degradation of perception under influence of emotion may be
related to alternate patterns of ocular muscles control.
3</p>
    </sec>
    <sec id="sec-3">
      <title>Measurement of human performance</title>
      <p>
        Various eyetracking techniques were implemented in our laboratory for last two
decades. We employed electrical, visual and infrared reflection-based methods
accordingly to the examination purpose and expected performance. Several
attempts to eyetracking were focused on:
– human equilibrium assessment - computer-assisted processing of
electronystagmographic response to Hallpike caloric test [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ],
– human performance in simple visual tasks: searching and counting [15],
reading [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ],
– human performance in complex visual tasks: visual ECG interpretation [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ],
visual attention in OCT image assessment, car driving, webpage navigation
etc.,
– visual scene characterization by factors of human perception [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ], [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ],
– control of the intelligent living environment [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ], [13].
      </p>
      <p>These works revealed a particular usability of the eyetracking in assessment of
human preferences and performance in completing visual tasks. Some tasks were
performed in real live (driving), but most of them were implemented as computer
simulation through displayed images (ECG signal, OCT image or a text message
to read). This setup facilitates standardization of measurement conditions and
stabilization of the observer making the results repeatable and reliable.
4</p>
    </sec>
    <sec id="sec-4">
      <title>Predicting of skills degradation with emotions</title>
      <p>Human performance degrades in certain circumstances due to internal or
external influences. Using the eyetracking as a reliable tool for instantaneous and
objective assessment of performance we also can estimate the degradation extent
and correlate it with the intensity of disturbing factors. This research is
expected not only to shed light on the dependence of human errors and efficiency
in various stress conditions but also to quantitatively measure the influence of
disturbing factor.</p>
      <p>One of the most interesting internal factor influencing human performance
are affects, probably due to their hardly controlled occurrence. Nevertheless,
recognition of affects combined with knowledge of human response is expected to
help in adaptation of intelligent computer interface to maintain the most effective
communication. To this point we aim at preparing visual tasks for measurement
of performance in neutral conditions as a reference and then its degradation
with increasing level of a specific emotion. This research is expected to reveal
external factors that evoke emotions and possibly influence human performance
in certain tasks.</p>
      <p>Other interesting issue is modeling human performance in presence of
external influencing factor of given intensity. Such model may be useful in adaptation
of computer communication interface to actual preferences of the operating
human. Planned experiments are expected to apply various information forms (i.e.
displays) to a computer operator being in gradually rising emotions in order
to rank these forms accordingly to their robustness. Having such personal
profiles we could predict and employ the most appropriate communication form
depending on actually detected emotional state.
5</p>
    </sec>
    <sec id="sec-5">
      <title>Case studies</title>
      <p>Industrial defects are very costly, whereas machinery are usually very complex
(e. g. Boeing 373 contains 367000 parts and Airbus A380 has an approximate 4
million parts [20]). Skilled engineers and technicians are subjects of a perpetual
training and examining process to maintain best possible working excellence.
Despite these efforts, little is known on how much stress conditions influence their
skills at the particular moment when an unexpected repair work is performed.
Since searching among real-life object, their representation in documentation
and comparing measurement readouts are purely visual tasks, we postulate
predicting the skills of each individual in wide range of unfavorable conditions in
order to apply the personalized interface providing the most proper information
in a most acceptable form.</p>
      <p>Entertainment selection belongs to typical tasks of personal digital advisors,
however the information based on age, gender or history of the spectator or
client is not sufficient to yield suitable suggestions. The particular purpose of
watching movies is rather to get involved emotionally than to know details of
another story. In addition, emotions are hardly explainable in a conscious way.
Therefore the objective detection of spectator’s emotions and preferences, which
can be easily captured by an eyetracker, is postulated to be used in context of
automatically derived semantic description of the footage. The scanpath
indicating the preferred character and meta-description of this character are helpful
in research for other movies containing characters of the same type.
6</p>
    </sec>
    <sec id="sec-6">
      <title>Conclusion</title>
      <p>Scanpath analysis is a promising tool for objective assessment of degradation
of human performance under various emotional conditions. The method is,
however, limited to visual tasks. Future works will be directed to establishing
appropriate models of scanpath response to standardized affective stimuli and
to optimizing detection methods towards their use as a background real-time
service in any digital communication equipment.</p>
      <p>
        Studies show that building of a cheap high speed eyetracker is still an
interesting scientific challenge [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]. Main limitation of visual sensors speed is a video
standard-related organization of the pixel readout, not present in single-beam
reflectometers. Therefore an interesting topic of further research may be
building of randomly addressable matrix of fast photocells controlled by a real-time
algorithm following the pupil or iris edge.
7
      </p>
    </sec>
    <sec id="sec-7">
      <title>Acknowledgement</title>
      <p>This scientific work is supported by the AGH University of Science and
Technology in year 2016 as a research project No. 11.11.120.612.</p>
    </sec>
    <sec id="sec-8">
      <title>Literatura</title>
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