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        <article-title>The 2nd Workshop &amp; Challenge on Micro-gesture Analysis for Hidden Emotion Understanding (MiGA2024)</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>August</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Korea</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
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          <label>0</label>
          <institution>Editors Haoyu Chen, University of Oulu</institution>
          ,
          <addr-line>Finland Björn W. Schuller</addr-line>
          ,
          <institution>University of Augsburg, Germany; Imperial College London, London/UK Ehsan Adeli, Stanford University, USA Guoying Zhao, University of Oulu</institution>
          ,
          <country country="FI">Finland</country>
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    <sec id="sec-1">
      <title>-</title>
      <p>Preface</p>
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    <sec id="sec-2">
      <title>The 2nd MiGA Workshop &amp; Challenge to explore using body gestures for hidden emotional state analysis, (MiGA2 in short) was jointly hosted at the IJCAI 2024 conference, in Jeju, Korea.</title>
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      <title>As introduced in 1st MiGA workshop, we focus on a specific group of body gestures, called micro-gestures (MGs), used in the psychology research field to interpret inner human feelings. With more and more research attention drawn to Micro-gestures, we continue to organize the second workshop focusing on micro-gestures this year.</title>
      <p>The second MiGA workshop and challenge seeks to broaden the research community focused on
micro-gesture analysis and its applications in emotion understanding, by introducing more modalities
into the task (both RGB and skeleton modalities). The event aims to foster dialogue among researchers
from academia and industry, highlighting key attributes influencing gesture-based emotion recognition
and evaluating recent advancements in the field. Similar to the first MiGA, we introduce two distinct
datasets (SMG and iMiGUE datasets) and corresponding benchmarks (classification and online
recognition), with the goal of shaping a new trajectory for the emotion AI community.</p>
    </sec>
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      <title>Building on the success of its inaugural event, MiGA 2024 was organized as a one-day workshop in</title>
    </sec>
    <sec id="sec-5">
      <title>Jeju, Korea. The workshop featured two invited talks and addressed topics spanning the theoretical</title>
      <p>foundations, technological advancements, and practical applications of gestures and micro-gestures in
emotion understanding. Discussions encompassed vision-based approaches for gesture-based emotion
recognition, including tasks such as classification, detection, and online recognition. The event also
highlighted newly collected datasets designed to support emotion understanding and explored diverse
applications of gestures and micro-gestures, such as emotion assessment in contexts like education. The</p>
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    <sec id="sec-6">
      <title>MiGA 2024 program, hosted in conjunction with IJCAI 2024, included two distinguished invited</title>
      <p>speakers: Prof. James Wang from Pennsylvania State University, USA, and Assistant Professor Hao</p>
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      <title>Tang from Peking University, China. Additionally, seven full papers were presented during the workshop, selected through a rigorous peer-review process.</title>
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    <sec id="sec-8">
      <title>We extend our heartfelt thanks to Prof. James Wang and Assistant Professor Hao Tang for their</title>
      <p>insightful and thought-provoking talks. We are equally grateful to all the participants for their
invaluable contributions, which were instrumental in making MiGA 2024 a remarkable event and a
dynamic forum for knowledge exchange within the community. Their engagement sparked vibrant
discussions on pivotal and contemporary advancements, highlighting an exceptional program that
exemplified cutting-edge work at the intersection of AI and emotion AI. Special thanks also gives to</p>
    </sec>
    <sec id="sec-9">
      <title>Associate Prof. Xiaobai Li for assisting this event. We look forward to the opportunity to host future events of this caliber, continuing to foster innovation and collaboration in this exciting field.</title>
      <p>The following full papers presenting original research works were accepted, and we divided them into three
sessions based on the content of the work.</p>
      <p>In Session1: MiGA Classification Schemes, Li et al. presented a framework the method is built on a two-stream
3D CNN backbone, dedicated to RGB and skeleton data each for micro-gesture classification, this scheme won
first place in the micro-gesture classification track. Huang et al. introduced their second-place winning scheme
for micro-gesture classification based on a framework named M2HEN, which constructs a heterogeneous
ensemble network by combining two fundamentally different deep learning models: a 3D convolution-based
model and a Transformer-based model. Wang et al. present a method rooted in the CLIP framework. Building
on Froster CLIP, they introduce a token attenuation strategy within the video encoding module, which
incrementally filters out less significant tokens at each layer.</p>
      <p>In Session2: MiGA Online Recognition Schemes, Huang, et al. introduced the first-runner scheme on the online
micro-gesture recognition track with a network that is primarily composed of two key elements: a 3D
convolutional network (RGBPose-Conv3D) and a multi-scale Transformer encoder. The approach introduced by
Li et al. is composed of a video encoder and an action decoder which incorporates a Mamba-MHSA module and
a multi-level interaction module.</p>
      <p>In Session3: Human Behaviour Analysis for Emotion Understanding, Xia, et al. reported a novel framework
that uses event data to recognize micro-gestures and micro-expressions, which is a novel research entry and the
features of an event camera meet the nature of those short and rapid movements of human behaviors. At last,
a summary work of all the plans proposed in the competition of MiGA 2 from Chen et al. was presented where
a detailed technical analysis of all the prize-winning schemes.</p>
      <sec id="sec-9-1">
        <title>Invited talk</title>
        <p>Artificial Emotional Intelligence and Bodily Expression In the Wild (Prof. James Wang, Pennsylvania</p>
      </sec>
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    <sec id="sec-10">
      <title>State University, USA)</title>
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    <sec id="sec-11">
      <title>Human motion understanding and synthesis (Assistant Professor Hao Tang, Peking University, China)</title>
      <sec id="sec-11-1">
        <title>Organizing Committee</title>
      </sec>
    </sec>
    <sec id="sec-12">
      <title>Haoyu Chen (University of Oulu, Finland)</title>
    </sec>
    <sec id="sec-13">
      <title>Guoying Zhao (University of Oulu, Finland)</title>
    </sec>
    <sec id="sec-14">
      <title>Ehsan Adeli (Stanford University, USA)</title>
      <sec id="sec-14-1">
        <title>Data Chairs</title>
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    </sec>
    <sec id="sec-15">
      <title>Marko Savic (University of Oulu, Finland)</title>
    </sec>
    <sec id="sec-16">
      <title>Atif Shah (University of Oulu, Finland)</title>
    </sec>
    <sec id="sec-17">
      <title>Abdelrahman Mostafa (University of Oulu, Finland)</title>
    </sec>
    <sec id="sec-18">
      <title>Björn W. Schuller (University of Augsburg, Germany; Imperial College London, London/UK)</title>
    </sec>
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