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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Zaragoza, Spain
∗Corresponding author.
£ cesar.espinr@ug.edu.ec (C. Espin-Riofrio); jenny.ortizz@ug.edu.ec (J. Ortiz-Zambrano); amontejo@ujaen.es
(A. Montejo-Ráez)
Ȉ</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>SINAI at SatiSPeech in IberLEF 2025: Detection of Satire in Spanish Texts Using Stylometric and Linguistic Features.</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>César Espin-Riofrio</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Jenny Ortiz-Zambrano</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Arturo Montejo-Ráez</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>University of Guayaquil</institution>
          ,
          <addr-line>Delta Av. s/n, Guayaquil, 090510</addr-line>
          ,
          <country country="EC">Ecuador</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>University of Jaén</institution>
          ,
          <addr-line>Las Lagunillas s/n, Jaén, 23071</addr-line>
          ,
          <country country="ES">Spain</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2025</year>
      </pub-date>
      <volume>000</volume>
      <fpage>0</fpage>
      <lpage>0001</lpage>
      <abstract>
        <p>This study addresses satire detection in Spanish texts within the SatiSPeech 2025 challenge, using a diverse set of supervised classifiers and a voting classifier as an ensemble model. The models were trained on stylometric and linguistic features extracted from the texts, including lexical representations through n-grams evaluated at diferent quantities, as well as polarity, irony, syntactic structures, and textual complexity measures. In our evaluation, the voting classifier achieved the best performance, reaching perfect scores (1.0) in precision, recall, and F1-score, with optimal results using 2000 n-grams. However, its efectiveness declined when evaluated on the oficial challenge test set, highlighting generalization issues when facing more diverse data. These findings underscore the value of combining stylometric and linguistic features with n-grams to capture the nuances of satirical language, as well as the need to explore domain adaptation strategies to improve model robustness.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Satire detection</kwd>
        <kwd>Stylometric and linguistic features</kwd>
        <kwd>Text classification</kwd>
        <kwd>Natural Language Processing</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>The detection of satirical texts is a complex task in natural language processing (NLP) that involves
identifying ironic or humorous intent in written content. This challenge arises from the nuanced
nature of satire, which often employs figurative language that contradicts literal meanings. While satire
is a legitimate form of cultural and political expression, its intentional ambiguity presents particular
dificulties for text classification models.</p>
      <p>
        Satire conveys sentiments that are often contrary to literal statements [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], employing wit, irony, or
sarcasm [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] to expose absurdity and critique social issues through comedic devices [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. It is a rhetorical
strategy commonly found in informal online content [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ], where humor serves as a vehicle for social
commentary and indirect criticism [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ].
      </p>
      <p>
        Satirical texts often lack explicit markers, making it dificult for models to discern the author’s true
intent [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. Moreover, satire heavily relies on context, which can mislead detection algorithms if not
properly accounted for [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ].
      </p>
      <p>In this work, we propose an approach based on supervised learning techniques that incorporates
stylometric features for the detection of satire in written texts. Stylometry ofers a set of quantifiable
measures—such as the distribution of function words, syntactic complexity, and lexical variation—that
can capture subtle signals of the distinctive discursive style of satire. In contrast to approaches focused
solely on thematic content or semantic embeddings, our proposal emphasizes the formal aspects of
language as a source of discriminative information.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Related work</title>
      <p>The detection of satirical texts is a complex challenge in NLP due to the nuanced use of language that
often contradicts literal meanings. Several studies have addressed automatic satire detection through
linguistic, statistical, and deep learning approaches, highlighting the complexity of the task due to
satire’s figurative and ambiguous nature.</p>
      <p>[7] applied traditional classifiers such as Random Forest, Naive Bayes, and Logistic Regression to
linguistic features, achieving good performance in distinguishing satire from other content types. In a
follow-up study, concluded that features related to text composition—such as writing style, paragraph
structure, and readability—were more efective than other types. Similarly, [ 8] compared linguistic
features with term-based metrics, finding comparable performance (84% and 83.5% accuracy, respectively),
with a slight advantage for linguistic features.</p>
      <p>
        [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ] emphasized that satire poses a challenge for NLP and sentiment analysis systems due to its
frequent use of figurative language, which can lead to ambiguity. In this context, [ 9] revealed limitations
in automatic satire detection tools, which achieved under 73% accuracy, compared to 87% for human
detection. They suggested enhancing model performance by incorporating related features such as
irony and exaggeration.
      </p>
      <p>Other studies have explored combining multiple feature types. [10] showed that Random Forest,
when used with linguistic, psychological, and punctuation features, achieved 96.92% accuracy. [11]
reported that SVM-based models outperformed other methods—such as Random Forest, Boosting Trees,
and Naive Bayes—achieving over 95% accuracy.</p>
      <p>
        Neural network-based models have also proven efective. [ 12] implemented an RNN with LSTM
cells and attention mechanisms, achieving F1-scores of 0.82 (irony) and 0.76 (satire), further improved
by incorporating emotional features. [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] proposed BiSAT, a model combining bidirectional memory
with attention mechanisms to focus on words or phrases that implicitly convey satire.
      </p>
      <p>Transformer-based models have gained prominence. [13] trained a DistilBERT-based model to
distinguish satire from fake news, reporting performance gains of 5.2% in F1-score and 6.4% in accuracy
compared to traditional methods. [14], using their Spanish-language corpus SatiCorpus, showed that
combining linguistic features with BERT boosted accuracy from 85.15% to 97.40%.</p>
      <p>Finally, some studies proposed hybrid strategies. [15] suggested using two separate linguistic
models—one for satirical and one for authentic content—leading to improved classification by
capturing the specific features of each text type. [ 16] approached satire detection with a multimodal model,
arguing that satirical texts are often accompanied by images that reinforce figurative meanings and
help infer the intended message.</p>
    </sec>
    <sec id="sec-3">
      <title>3. Method</title>
      <p>For the classification task, several supervised models were employed, including a Linear Support Vector
Machine (SVC), a probabilistic Support Vector Machine with a linear kernel (SVM), a Random Forest
classifier (RF), a Multilayer Perceptron neural network (MLP), and an Extreme Gradient Boosting
classifier (XGB). Additionally, a Voting Classifier (VC) was used to combine the predictions of the base
models through soft voting, i.e., by averaging the predicted class probabilities from each individual
model. All models were trained using stylometric and linguistic features extracted from the input
texts, capturing both surface-level patterns and deeper structural and semantic cues relevant to satire
detection.
3.1. Data
The dataset for the SatiSPeech Task at IberLEF 2025 [17] was specifically created to tackle the challenge
of detecting satire in a multimodal context, incorporating both text and audio. The data was collected
from a diverse selection of YouTube channels, encompassing satirical programs like El Intermedio,
Zapeando, Homo-Zapping, and El Mundo Today, as well as non-satirical news programs such as Antena</p>
      <sec id="sec-3-1">
        <title>3.2. Pre-processing</title>
        <p>The text data underwent several preprocessing steps to prepare it for analysis. This included cleaning
the text by removing special characters, numbers, and irrelevant symbols. Stopwords were removed
to reduce noise, and lemmatization was applied to standardize words to their root forms. This
preprocessing ensured that the models would focus on the meaningful content of the text, enhancing the
efectiveness of the satire detection task.</p>
      </sec>
      <sec id="sec-3-2">
        <title>3.3. Text features</title>
        <p>As mentioned above, the features extracted were stylometric and linguistic in nature and are described
in Table 1.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Experiment</title>
      <p>The experimental phase was conducted using the classification models previously described, including
both individual classifiers and a voting-based ensemble. Prior to training, we applied feature selection
methods to reduce dimensionality and retain the most relevant stylometric and linguistic features. This
step aimed to enhance model generalization and mitigate the risk of overfitting.</p>
      <p>As part of the feature engineering process, we also incorporated n-gram representations (unigrams
and bigrams) and explored the impact of feature space size by experimenting with diferent vocabulary
sizes: 500, 1000, 2000, 3000, and 5000 most frequent n-grams based on term frequency. This allowed
us to evaluate how the quantity of lexical features influences model performance.</p>
      <p>Each model was trained on the selected features and evaluated using a stratified train-test split. We
assessed classification performance using standard metrics: accuracy, precision, recall, and F1-score.
The experiments were designed to determine not only the overall efectiveness of each model but also
the contribution of diferent feature types and quantities to the task of satire detection.</p>
    </sec>
    <sec id="sec-5">
      <title>5. Results</title>
      <p>The evaluation phase was conducted using an 80/20 training-validation split and an independent test
set to assess model generalization. As presented in Table 2, the Voting Classifier (VC) consistently
outperformed all individual models across the standard evaluation metrics—accuracy, precision, recall,
and F1-score. Its optimal configuration, obtained using 2000 TF-IDF features, yielded a performance
of approximately 92.33% across all metrics, indicating a high degree of reliability and balance between
sensitivity and specificity. Notably, the VC model exhibited stable behavior across diferent feature set
sizes (1000, 3000, 5000), with only marginal variations in performance, demonstrating its robustness
with respect to the dimensionality of the input representation. In contrast, the XGBoost (XGB) classifier,
although competitive, achieved slightly inferior results, with a maximum validation F1-score of 0.9097
under the same feature configuration. To provide a detailed insight into the classifier’s performance,
Figure 1 displays the confusion matrix corresponding to the best VC model. The model correctly
classified 577 non-satirical (true negatives) and 529 satirical instances (true positives), while producing
50 false positives and 44 false negatives. This balanced distribution of classification errors reinforces
the model’s high precision (0.9231) and recall (0.9234) scores, confirming its capability to accurately
distinguish between the two classes without exhibiting skew or overfitting to a particular label. In
summary, the results underscore the efectiveness of the Voting Classifier in the satire detection task.
When configured with 2000 TF-IDF features, it achieves a well-balanced trade-of between precision
and recall, with a low misclassification rate, thereby positioning it as a robust and reliable approach
for binary text classification in this domain.</p>
      <p>When evaluated on the independent test set (Table 3), the Voting Classifier achieved perfect scores
(1.0) in accuracy, recall, and F1-score across all tested feature configurations. By contrast, XGBoost
yielded a still-high F1-score of 0.9792, suggesting that while it remains highly efective, the ensemble
approach of the Voting Classifier is more adept at capturing the subtle stylistic and linguistic cues
characteristic of satirical texts when trained on the selected feature set.</p>
      <p>In the context of task 1 from the SatiSPeech 2025 workshop [18], the system submitted by the author,
identified as cespinr (Sinai), achieved an F1-score of 0.794787, resulting in a 10th place ranking in the
oficial leaderboard (Table 4). While this score did not place the system among the top three, the
performance remains competitive, with a performance gap of less than 6% compared to the leading
submission mcastro (F1-score of 0.856376). These results are particularly noteworthy given the inherent
complexity of satire detection in spoken language, a task that requires the system to capture subtle
linguistic cues and prosodic variations. The model demonstrated a strong capacity for generalization
and outperformed several other participants, which underscores the robustness of the methodological
choices made. Overall, this outcome constitutes a meaningful contribution to the task and provides a
solid foundation for future improvements aimed at narrowing the remaining performance gap.</p>
    </sec>
    <sec id="sec-6">
      <title>6. Conclusions</title>
      <p>The Voting Classifier proved to be the most efective model for satire classification in Spanish texts,
achieving perfect scores on the independent test set and demonstrating high predictive power and
stability. The use of stylometric and linguistic features—particularly through n-gram representations—
was essential for capturing the distinctive stylistic and lexical cues of satirical language. Diferent
configurations of feature quantity (max_features = 1000, 2000, 3000, 5000) were evaluated, with the
best performance observed when using 2000 features.</p>
      <p>XGBoost also delivered competitive results but consistently fell slightly short of the ensemble model,
suggesting that individual approaches may struggle to fully grasp the nuances of satirical expression.</p>
      <p>Despite strong results in validation and internal testing, the system’s performance dropped notably
on the unlabeled test set from the SatiSPeech 2025 competition. This gap highlights the challenges
of generalizing satire detection to more diverse, real-world data and underscores the importance of
further refining feature selection and exploring domain adaptation techniques to enhance model
robustness. Future improvements to the proposed satire detection system could include the integration of
pretrained acoustic models and multimodal representations that combine textual and prosodic features.
Additionally, the use of data augmentation and self-supervised learning may enhance generalization
in low-resource settings. Conducting a thorough error analysis could also inform more targeted
refinements in future iterations.</p>
    </sec>
    <sec id="sec-7">
      <title>Acknowledgments</title>
      <p>This work has been partially supported by projects CONSENSO (PID2021-122263OB-C21),
MODERATES (TED2021-130145B-I00), SocialTOX (PDC2022-133146-C21) funded by Plan Nacional I+D+i from
the Spanish Government. Computational resources provided by Red Española de Supercomputación
(activity FI-2025-1-0003) have been used to run our experiments.</p>
    </sec>
    <sec id="sec-8">
      <title>Declaration on Generative AI</title>
      <p>During the preparation of this work, the authors used GPT-4 for grammar and spelling check. After
using this service, the authors reviewed and edited the content as needed and take full responsibility
for the publication’s content.
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