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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>ORCID:</journal-title>
      </journal-title-group>
      <issn pub-type="ppub">1613-0073</issn>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Fine-tuning language models for emotion recognition in Lithuanian texts using neural machine translation of training datasets</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Mindaugas Petkevičius</string-name>
          <email>mindaugas.petkevicius@vdu.lt</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Daiva Vitkutė-Adžgauskienė</string-name>
          <email>daiva.vitkute@vdu.lt</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Workshop</string-name>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Vytautas Magnus University</institution>
          ,
          <addr-line>K. Donelaičio g. 58, Kaunas, 44248</addr-line>
          ,
          <country country="LT">Lithuania</country>
        </aff>
      </contrib-group>
      <volume>000</volume>
      <fpage>0</fpage>
      <lpage>0002</lpage>
      <abstract>
        <p>Lithuanian language is a complex and rich language with a unique grammar structure, making it an interesting choice for natural language processing (NLP) tasks such as emotion detection. This study provides helpful insights into the emotional nuances of Lithuanian texts by utilizing a translated and augmented emotion dataset. We present a methodology that leverages translated datasets for emotion recognition and augmentation approaches to improve the performance of emotion identification models in low-resource languages. We compared the outcomes of transformer-based language models, such as RoBERTa, LaBSE, and LitLat BERT on the translated and augmented data. Our results demonstrated that LitLat BERT, which is primarily trained on Lithuanian texts, showed the most significant improvement in performance when data augmentation was applied. We conclude that LitLat BERT could be the preferred choice for emotion recognition tasks for Lithuanian language due to its specialized training and enhanced adaptability when provided with diverse and augmented data. This study provides valuable insights into the challenges and potential solutions for emotion identification tasks in morphology-rich languages, like Lithuanian language. NLP, emotion detection, transformer-based models, BERT, translation, augmentation, 28th International Conference Information Society and University Studies - IVUS 2023 Proceedings</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>Emotion recognition in texts is an important natural language processing (NLP) task and has
wideranging applications, including sentiment analysis, customer support, mental health monitoring and
others. With the rapid development of deep learning techniques, significant advancements have been
made in emotion recognition for high-resource languages, such as English, Chinese and Spanish.
However, research in low-resource languages, like Lithuanian language, remains limited due to the
scarcity of annotated datasets and the lack of pre-trained models.</p>
      <p>In this paper, we propose a methodology for improving emotion recognition performance in
lowresource and morphology-rich languages, using translated datasets and augmentation approaches for
the Lithuanian language.</p>
      <p>In order to reach our goal, we perform the following tasks: related work analysis (Section 2), dataset
analysis (Section 3), methodology for translating and augmenting datasets, as well as fine-tuning
transformer-based language models (Section 4), experimental evaluation of different fine-tuned models
(Section 5), conclusions and future plans (Section 6).</p>
      <p>2023 Copyright for this paper by its authors.
CEUR</p>
      <p>ceur-ws.org</p>
    </sec>
    <sec id="sec-2">
      <title>2. Related Works</title>
      <p>
        Research in emotion recognition for low-resource languages has been an area of growing interest in
recent years [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. Several studies have proposed different approaches to tackle this problem, such as
cross-lingual transfer learning [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ], data augmentation technique [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ], and leveraging unsupervised
methods [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ].
      </p>
      <p>
        Also there have been studies, where emotion detection datasets across 19 languages were trained on
a multilingual emotion prediction model, XLM-EMO, for social media data, which showed competitive
performance in a zero-shot setting and is particularly useful for low-resource languages [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ].
      </p>
      <p>
        In another study, researchers addressed the shortage of annotated gold standard resources for
emotion mining by presenting a multilingual emotion dataset of tweets in English and Spanish, labeled
with one of seven emotions and proposed a machine learning approach for automatically detecting
emotions in tweets for both languages [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ].
      </p>
      <p>
        Also, researchers conducted experiments on sentiment and emotion recognition for English and
Polish texts in the context of a chatbot, creating a parallel corpus named CORTEX and employing
various classifiers such as Support Vector Machines, fastText, and BERT, with BERT-based models
yielding the highest accuracy and F1-scores, although results for Polish were slightly inferior to those
for English [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ].
      </p>
      <p>However, these methods are often problematic due to the need for parallel data, noise adding, or
relying on uncontrolled training goals that may not match the target task.</p>
    </sec>
    <sec id="sec-3">
      <title>3. Dataset</title>
      <p>
        We selected the CARER (Contextualized Affect Representations for Emotion Recognition) [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ]
dataset, a widely-used and well-annotated dataset for emotion recognition tasks for our research in this
study. The dataset contains textual data, labeled with six different emotions: sadness, joy, love, anger,
fear, and surprise. In this section, we provide a brief overview of the dataset and discuss the reasons
for choosing it for our emotion recognition task for the Lithuanian language.
      </p>
      <p>Type
Training
Validation</p>
      <p>Testing
Total</p>
      <p>This dataset is a collection of 20,000 English social media text samples, with each sample annotated
with one of the six emotions. The dataset is split in the following way: 16,000 samples for training,
2,000 samples for validation, and 2,000 samples for testing. The data is diverse, containing a variety of
sentence structures and extensive vocabulary, allowing the models to learn the nuances of different
emotions in textual data. Label distribution is presented in Figure 1 and text length distribution is
presented in Figure 2.</p>
      <sec id="sec-3-1">
        <title>There were several reasons for selecting this dataset for our study:</title>
        <p>1. High-quality annotations: accurate and well-annotated labels for model training and evaluation.
2. Diversity of emotions: wide range of emotions for learning linguistic patterns and improved
emotion recognition.
3. Transfer learning suitability: English dataset enables transfer learning for low-resource</p>
        <p>Lithuanian tasks using translations.
4. Compatibility with models/frameworks: Widely used dataset, compatible with pre-trained
models, simplifies incorporation and focuses on emotion recognition challenges.</p>
        <p>Summarizing, the dataset was chosen due to its high-quality annotations, diversity of emotions,
suitability for transfer learning, and compatibility with existing models and frameworks. By leveraging
this dataset in conjunction with language-specific models and translation techniques, we can effectively
address the challenges associated with emotion identification in low-resource languages such as
Lithuanian.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Methodology</title>
      <p>The methodology part covers the methods applied in this research: (1) translation of the dataset using
neural machine translation models; (2) augmentation process for enriching and balancing the dataset;
(3) fine-tuning transformer-based models for emotion classification task.</p>
    </sec>
    <sec id="sec-5">
      <title>4.1. Translation of the dataset</title>
      <p>
        For the emotion recognition task, the choice of translation service plays a crucial role in generating
high-quality translated datasets. To increase the linguistic diversity of our dataset, we translated these
datasets using two state-of-the-art machine translation models:
1. Opus-MT [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]: An open-source neural machine translation model trained on a variety of
multilingual parallel corpora.
2. facebook/m2m100_418M [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ] A many-to-many multilingual translation model developed by
Facebook AI [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ]. It is designed to support translation between 100 languages and is trained on
a large-scale parallel corpus.
      </p>
      <p>
        However, depending on specific requirements and constraints of certain projects, DeepL [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] or
Google Translate [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ] could also be viable options.
      </p>
      <p>By combining and translating these datasets, we aimed to create a rich, diverse dataset that covers a
wide range of emotions, contexts and social texts.</p>
      <p>When choosing a translation service, it is important to think about the quality of the translation, the
number of domains it covers, and how well it fits the task at hand. In some situations, it might be helpful
to improve the quality of the translated information by using a combined approach, merging translations
from more than one service.</p>
      <p>
        After combining the translations, generated by both models, we obtained a dataset with the following
distribution of emotion labels, as displayed on Figure 3.
It was observed that certain emotion classes, specifically love and surprise, have a significantly lower
number of samples in the dataset. To address this imbalance and improve the performance of our
models, we decided to augment the dataset by applying synonym replacement to the underrepresented
classes. Synonym replacement has showed good results for dataset augmentation [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ].
      </p>
    </sec>
    <sec id="sec-6">
      <title>4.2. Augmentation</title>
      <p>In our study, we employed data augmentation techniques to enhance the performance of the emotion
recognition models and improve their robustness to different translations and imbalanced emotion
distributions. For this purpose, we used synonym replacement as our data augmentation method. In this
section, we describe the process of synonym replacement and its importance in the context of the
Lithuanian language.</p>
      <p>Synonym replacement is accomplished by replacing words in a given text with their synonyms in
order to create new and slightly different variations of the original text while preserving its meaning
and sentiment. The process of synonym replacement is shown in Figure 4.</p>
      <p>
        We used the following algorithm to implement synonym replacement in our study:
1. Tokenization: Tokenize the Lithuanian text samples using a spaCy [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ] library tokenizer.
2. Vector representation: Represent each word token using the GloVe [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ] word vectors provided
by the spaCy library. These vectors capture the semantic word meaning in a high-dimensional
space.
3. Similarity computation: For each word token, compute the cosine similarity between its vector
representation and the vectors of other words in the vocabulary to identify the most semantically
similar words like synonyms.
4. Synonym selection: Select the most similar words, matching the same part-of-speech (POS)
and morphology, as the original word token. This is crucial for preserving the grammatical
correctness of the text, especially in a morphologically rich language like Lithuanian.
5. Replacement: Randomly replace a subset of word tokens in the text with their selected
synonyms, ensuring that the replacements do not alter the text's overall meaning or sentiment.
Synonym replacement increases the performance of the emotion recognition model for Lithuanian by
addressing morphological richness, promoting diverse training data, and handling imbalanced datasets.
It preserves grammatical correctness and overall sentiment, exposes models to various linguistic
patterns, and generates additional samples for underrepresented emotion classes.
      </p>
      <p>After analyzing the dataset, we decided to add additional augmented texts for the labels love and
surprise, which had the fewest occurrences. The updated distribution of emotion labels in the dataset is
presented in Figure 5.
This balanced distribution of emotion labels enables the models to learn better representations of
different emotions in the text, and potentially improves their overall performance in the emotion
identification task. Final version of the dataset is shown in Table 2.</p>
    </sec>
    <sec id="sec-7">
      <title>4.3. Training and fine-tuning language models</title>
      <p>
        We chose three transformer-based models for our experiments for investigating the impact of
translation quality and data augmentation on emotion recognition tasks in Lithuanian:
1. RoBERTa [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ] (xlm-roberta-base): A multilingual version of RoBERTa pretrained on various
languages, offering state-of-the-art performance in numerous NLP tasks.
2. LaBSE [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] (sentence-transformers): A sentence-level transformer architecture designed for
cross-lingual tasks, generating fixed-size representations for multilingual text data.
3. Litlat BERT [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] (litlat-bert): A fine-tuned BERT [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ] model tailored to Lithuanian and Latvian
languages, pretrained on a large corpus of Lithuanian and Latvian text data.
      </p>
      <p>By comparing these diverse models, we aimed to identify the most efficient approach for emotion
recognition for the Lithuanian language, and evaluate the impact of translation quality and data
augmentation techniques on their performance.</p>
    </sec>
    <sec id="sec-8">
      <title>5. Experiments and results</title>
      <p>Experiments were carried out in a series of tasks:
1. Firstly, the quality of translations was assessed.
2. Secondly, base model for English language was fine-tuned using original English dataset.
3. Thirdly, the obtained word embedding models were evaluated using the adapted intrinsic
evaluation benchmarks.
4. Finally, the resulting data was examined in order to determine the effect of different
hyperparameters on benchmark evaluation results.</p>
    </sec>
    <sec id="sec-9">
      <title>5.1. Assessing quality of the translations</title>
      <p>In our study, we used two translation models to generate Lithuanian versions of the dataset. Due to
the morphological richness of Lithuanian, achieving consistent translations can be challenging.
Translation models may struggle to generate accurate translations, which can impact emotion
identification performance.</p>
      <p>
        However, as long as the main sentiment remains consistent, this impact is expected to be minimal.
Training models on diverse translation styles can improve their robustness and performance in
realworld scenarios [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ].
      </p>
      <p>To assess translation quality, we calculated the BLEU (bilingual evaluation understudy) 0.2337 and
WER (word error rate) 0.3349 scores for the translations. These scores indicate significant differences
between the two models, attributable to the complex nature of the Lithuanian language. Despite the
differences, the main idea is generally preserved, enabling emotion identification models to learn from
the dataset. This highlights the importance of translation quality in low-resource language tasks and the
need for more robust models to handle translation inconsistencies.</p>
    </sec>
    <sec id="sec-10">
      <title>5.2. Base model trained on original English dataset</title>
      <p>In order to establish a baseline for comparison, we trained a base model on the original English
dataset. This experiment allowed us to evaluate the performance of the emotion identification models
when trained on a high-resource language, like the English language, and compare the results with those
obtained for the Lithuanian translations.</p>
      <p>
        We selected the xlm-roberta-base model for this experiment, as it has demonstrated strong
performance in various NLP tasks [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ], including emotion identification. The results obtained from
training the xlm-roberta-base model on the original English dataset are presented in Table 3:
      </p>
      <p>As expected, the xlm-roberta-base model achieved a high level of performance when trained on the
English dataset, with an accuracy of 0.9305 and an F1 score of 0.9313. These results serve as a
benchmark for assessing the performance of the emotion identification models trained on the translated
Lithuanian datasets, enabling us to better understand the challenges and potential improvements
associated with semantically rich and low-resource languages.</p>
    </sec>
    <sec id="sec-11">
      <title>5.3. Fine-tuning models for emotion detection</title>
      <p>In the second training experiment, we aimed to evaluate the performance of the emotion
identification models when exposed to a diverse range of translation styles and potential errors. For this
purpose, we combined the datasets generated using both translation models. This approach provided
the models with a more varied and potentially challenging dataset, allowing us to assess the model's
adaptability and robustness in the face of translation inconsistencies. Results are provided in Table 4.</p>
      <p>Comparing the results of the experiments, we observed that when trained on the original English
dataset, the xlm-roberta-base model achieved the highest accuracy, precision, recall, and F1 score.
However, when using translated dataset, the performance of xlm-roberta-base decreased but remained
competitive. In this scenario, LaBSE showed slightly better accuracy and F1 score compared to
lmroberta-base, while LitLat BERT (litlat-bert) had marginally lower results.</p>
      <p>This comparison demonstrates that translation quality and the choice of translation model can impact
the performance of emotion identification models in low-resource languages like Lithuanian. Moreover,
they emphasize the need for developing more robust models that can effectively handle translation
inconsistencies and variations in the text.</p>
    </sec>
    <sec id="sec-12">
      <title>5.4. Fine-tuning models for emotion detection with augmented dataset</title>
      <p>In the third training experiment, we aimed to evaluate the performance of the emotion identification
models when exposed to a diverse range of translation styles, potential errors, and augmented data. For
this purpose, we used the translated dataset, and, additionally, applied data augmentation techniques.
This approach provided models with a more varied and potentially challenging dataset, allowing us to
assess the models' adaptability and robustness in the face of translation inconsistencies and the
additional variations introduced by data augmentation. Table 5 shows the results.</p>
      <p>When comparing the results obtained from the models trained with and without data augmentation,
we can observe significant differences. After data augmentation was applied, the performance of LitLat
BERT reached a highest accuracy with 0.813 and F1 score of 8 of 0.81.</p>
      <p>The improvement in LitLat BERT's performance can be attributed to the fact that it is primarily
trained on Lithuanian texts, unlike the other multi-language models. This specialized training allows
LitLat BERT to be more sensitive to the nuances and linguistic patterns specific to the Lithuanian
language. When the dataset is augmented, the model can effectively leverage its knowledge of
Lithuanian text to adapt to a broader range of linguistic variations, improving its overall performance.
Consequently, LitLat BERT could be the preferred choice for emotion identification tasks in Lithuanian
due to its targeted training and enhanced adaptability when provided with diverse and augmented data.</p>
    </sec>
    <sec id="sec-13">
      <title>6. Conclusions</title>
      <p>This study marks the initial effort to translate and adapt a training dataset for downstream NLP
tasks in the Lithuanian language. While we did not achieve the same performance level as the original
English dataset, our findings demonstrate that models can effectively be trained on translated and
augmented data for the Lithuanian context.</p>
      <p>In summary, data augmentation, using synonym replacement, is an effective method for enhancing
the performance and robustness of emotion identification models in low-resource languages like
Lithuanian, by addressing the challenges posed by the morphological richness of the language and
generating diverse and balanced training data.</p>
      <p>In the future, we intend to accomplish a more in-depth study of how well these services translate in
the context of detecting emotions. We also intend to look into ways of improving the translation quality
by fine-tuning the translation models.
7. References</p>
      <sec id="sec-13-1">
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