=Paper= {{Paper |id=Vol-3740/paper-266 |storemode=property |title=Binary Battle: Leveraging Machine Learning and Transfer Learning Models to Distinguish between Conspiracy Theories and Critical Thinking |pdfUrl=https://ceur-ws.org/Vol-3740/paper-266.pdf |volume=Vol-3740 |authors=Sidharth Mahesh,Sonith Divakaran,Kavya Girish,Hosahalli Lakshmaiah Shashirekha |dblpUrl=https://dblp.org/rec/conf/clef/MaheshDGS24 }} ==Binary Battle: Leveraging Machine Learning and Transfer Learning Models to Distinguish between Conspiracy Theories and Critical Thinking== https://ceur-ws.org/Vol-3740/paper-266.pdf
                         Binary Battle: Leveraging Machine Learning and Transfer
                         Learning Models to Distinguish between Conspiracy
                         Theories and Critical Thinking
                         Sidharth Mahesh† , Sonith Divakaran† , Kavya Girish† and
                         Hosahalli Lakshmaiah Shashirekha*,†
                         Department of Computer Science, Mangalore University, Mangalore, Karnataka, India


                                     Abstract
                                     In the context of automatic content moderation Natural Language Processing (NLP) has a complex task when it
                                     comes to distinguishing between conspiracy theories and critical thinking. While conspiracy theories present
                                     complex narratives attributing significant events to covert actions by powerful and malicious entities, critical
                                     thinking involves scrutinizing decisions without resorting to any sinister explanations. Making this distinction
                                     is essential to avoid the mislabeling of valid criticism as conspiracy, which may unintentionally lead people to
                                     join conspiracy communities. Conspiratorial and critical narratives are both examples of oppositional thinking,
                                     which is important in public debate, particularly in controversial areas like public health. In this direction,
                                     “Oppositional thinking analysis: Conspiracy theories vs critical thinking narratives"- a shared task organized
                                     at PAN 2024, invites the research community to address the challenges of distinguishing between conspiracy
                                     and critical texts in English and Spanish languages. To explore the strategies for distinguishing between critical
                                     and conspiracy texts in English and Spanish on social media platforms, in this paper, we - team MUCS, describe
                                     the models proposed for Subtask-1: "Distinguishing between critical and conspiracy texts" of the shared task.
                                     We explored machine learning models trained with Term Frequency-Inverse Document Frequency (TF-IDF) of
                                     char n-grams in the range (1, 5) and transfer learning techniques using several BERT variants fine-tuned with
                                     the given English and Spanish datasets, to classify the given unlabeled English and Spanish text into one of the
                                     two categories - ’CONSPIRACY’ or ’CRITICAL’. Among the proposed models, English_BERT and Spanish_BERT
                                     models obtained Matthews Correlation Coefficient (MCC) scores of 0.7162 and 0.6293 for English and Spanish
                                     languages respectively.

                                     Keywords
                                     Oppositional thinking analysis: Conspiracy vs Critical Narratives, Oppositional Thinking, Conspiracy Theories,
                                     Machine Learning, Transfer Learning




                         1. Introduction
                         Conspiracy theories and critical thinking are two forms of oppositional thinking which are common
                         especially on contentious issues and analyzing oppositional thinking entails scrutinizing narratives that
                         question mainstream perspectives. Further, understanding the impact of different types of oppositional
                         thinking on public opinion and behavior is crucial [1]. While critical thinking fosters constructive
                         and democratic debate characterized by reasoned questioning without unfounded explanations, con-
                         spiratorial thinking can lead to misinformation and social conflict attributing the significant events to
                         hidden malevolent forces[2]. In social and political discourse, conspiracy theories can have detrimental
                         effects on an individual as well as on organisations or the entire society. These theories suggest that
                         major social (encompass gatherings and activities involving people) and political events (activities
                         related to government and leadership) with careful planning by powerful and malevolent entities can
                         spread false information and stir social unrest. Conspiracy theories have been associated with violence,
                         war, terrorism, prejudice, poor health choices, and denial of climate change [3]. In contrast, critical


                         CLEF 2024 – Conference and Labs of the Evaluation Forum, September 9–12, 2024, Grenoble, France
                         *
                           Corresponding author.
                         †
                           All authors contributed equally.
                         $ sidharthmaheshedu@gmail.com (S. Mahesh); sonithksd@gmail.com (S. Divakaran); kavyamujk@gmail.com (K. Girish);
                         hlsrekha@mangaloreuniversity.ac.in (H. L. Shashirekha)
                                  © 2024 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).


CEUR
                  ceur-ws.org
Workshop      ISSN 1613-0073
Proceedings
thinking involves analyzing and questioning decisions, particularly in areas like public health, without
attributing events to hidden conspiracies.

    Table 1
    Sample text and their corresponding labels in English dataset




   Mislabeling critical discourse as conspiratorial can suppress healthy debate and alienate individuals
who are merely questioning decisions and mislabeling critical conversation as conspiracy can stifle
constructive disagreement and alienate people who are only challenging judgements [3, 4]. This leads
to a climate of mistrust and inhibits the exchange of open and sincere ideas. On the other hand, failing
to identify and address conspiratorial narratives allows the spread of misinformation, leading to societal
division and mistrust. Thus, accurate differentiation between the two forms of oppositional thinking
by content moderation systems is essential to avoid marginalizing legitimate criticism and preventing
individuals from being drawn into conspiracy communities by mistaking valid critique for conspiracy
theories [5]. Additionally, distinguishing between these forms of oppositional thinking is essential for
public discourse and social harmony.
   Distinguishing between the oppositional forms of thinking is challenging due to the nuanced and
overlapping content, the context-dependent nature of oppositional statements, and oppositional attitudes
[6]. Further, differentiating between well-founded critical and unfounded conspiracy theories require
advanced and context-aware NLP techniques and developing such techniques is crucial for improving
the accuracy and fairness of content moderation systems. To address the challenges of distinguishing
between the oppositional forms of thinking, "Oppositional thinking analysis: Conspiracy theories vs
Critical thinking narratives" shared task organized at PAN 2024 [7], invites the research community to
develop models to distinguish between conspiracy and critical thinking texts in English and Spanish
languages. The shared task has two subtasks in English and Spanish languages and we - team MUCS
participated in only Subtask-1: ’Distinguishing between critical and conspiracy texts’. This subtask
having two categories - ’CONSPIRACY’ and ’CRITICAL’, is modeled as a binary classification problem.
In this paper, we describe various machine learning models trained with TF-IDF of char n-grams in the
range (1, 5) and transfer learning techniques using several BERT variants fine-tuned with the given
Engish and Spanish datasets, to classify the given unlabeled English and Spanish text into one of the
two categories - ’CONSPIRACY’ or ’CRITICAL’. The sample text from the given datasets for English
and Spanish are shown in the Tables 1 and 2 respectively.
   The rest of the paper is organized as follows: Section 2 describes the recent literature on the two
forms of oppositional thinking and Section 3 focuses on the description of the proposed models followed
by the experiments and results in Section 4. The paper concludes with future works in Section 5.


2. Related Work
Conspiracy theories involve elaborate, unverified claims driven by cognitive biases and emotional
needs, often rejecting official explanations without sufficient evidence. In contrast, critical thinking is
characterized by objective analysis, logical reasoning, and the evaluation of evidence from multiple
sources. Research highlights that while conspiracy beliefs are linked to cognitive biases and feelings of
    Table 2
    Sample text with the English translation and corresponding labels in Spanish dataset




 powerlessness, critical thinking fosters informed decision-making and intellectual humility [3].
    To explore different strategies for the conspiracy textual content classification in social media,
 Moosleitner and Murauer [8] employed machine learning models (Support Vector Machines (SVM),
 Multinomial Naive Bayes (MNB), and Extremely randomized Trees) trained with TF-IDF of character,
word and Document Term n-grams based features and BERT models (BERT-base, RoBERTa, and
 DistilBERT) for English text. For the three tasks: Task 1 - Text-Based Misinformation Detection, Task 2
- Text-Based Conspiracy Theories Recognition, and Task 3 - Text-Based Combined Misinformation and
 Conspiracies Detection, their proposed BERT-base models outperformed all other models in all three
 tasks obtaining MCC scores of 0.3184, 0.3624, 0.3347 for Tasks 1, 2, and 3 respectively. For detecting fake
 news during covid-19 pandemic, Tahat et al. [9] proposed a hybrid analysis using Structural Equation
 Modelling (SEM) and machine learning classification algorithms such as BayesNet, AdaBoostM1, LWL,
 Logistic, J48, and OneR, for English dataset. Among the proposed models J48 classifier outperformed
 other machine learning classifiers with an F-Measure score of 0.863. Peskine et al. [10] proposed
 transformer model (composed of an ensembling of CT-BERT models) and a node embedding-based
 techniques (node2vec + Multilayer Perceptron (MLP) classification head) to detect COVID-19-related
 conspiracy theories in tweets in English language which consists of three subtasks: Task 1 - Text-Based
 Misinformation and Conspiracies Detection, Task 2 - Graph-Based Conspiracy Source Detection, and
Task 3 - Graph and Text-Based Conspiracy Detection. Their proposed CT-BERT ensembling model
 obtained a MCC score of 0.710 and 0.719 for Task 1 and Task 3 respectively, and node2vec + MLP model
 obtained a MCC of 0.355 for Task 2.
    Giachanou et al. [2] performed a comparative analysis of various profiles and psychological and
 linguistic characteristics in social media texts of users who share posts about conspiracy theories. The
 authors then compared the effectiveness of these characteristics for predicting whether a user is a
 conspiracy propagator or not by proposing ConspiDetector, a model that is based on a Convolutional
 Neural Network (CNN) which combines word embeddings with psycho-linguistic characteristics ex-
 tracted from the tweets of users to detect conspiracy propagators. Recordare et al. [11] implemented
various machine learning classifiers (Logistic Regression (LR), k-Nearest Neighbours (kNN), Naive
 Bayes (NB), SVM, Decision Trees (DT), Random Forest (RF), Gradient Boosting: XGBoost and LightGBM,
 Quadratic Discriminant Analysis, MLP, Ridge Classifier, and Linear Discriminant Analysis, trained
with Bidirectional Auto-Regressive Transformers (bart)-large-Multi-Genre natural language inference
 features for identifying users who propagate conspiracy theories based on a rich set of 871 features in
English language. Among all the proposed models, LightGBM classifier outperformed other models
with a macro F1 score of 0.87. To identify whether an article belongs to conspiracy theory or not in
English language, Ghasemizade and Onaolapo [12] proposed machine learning classifiers (RF, SVM,
k-NN, NB) trained with TF-IDF of word unigrams and deep learning model trained with padded and
embedded text sequences. Using their respective tokenizers, tokenized and padded text sequences were
taken as inputs to train the transformer models - BERT and RoBERTa. Their proposed RoBERTa model
outperformed other models with a macro F1 score of 87%.
   The above literature highlights extensive research efforts aimed at detecting conspiracy theories
utilizing a range of machine learning, deep learning, and transfer learning models. These studies offer
valuable insights into the detection of conspiracy theories. However, they do not specifically address
the distinction between conspiracy theories and critical thinking within the framework of oppositional
thinking. This gap suggests a need for further research to effectively distinguish between these concepts,
encouraging the creation of new models for this specific type of application.


3. Methodology
We have explored machine learning and transfer learning models for distinguishing between critical
and conspiracy texts in English and Spanish and the steps involved in the construction of these models
are explained in the following subsections.




Figure 1: Framework of the proposed machine learning model



3.1. Machine Learning models
The framework of machine learning model is visualized in Figure 1 and the steps included in building
these classifiers are explained below:

3.1.1. Pre-processing
Pre-processing is the preliminary step in building learning models and it involves cleaning and trans-
forming the raw text data to a suitable format required for subsequent processing. Usually, text data
contains noise in the form of: user mentions, hashtags, punctuation, digits, and hyperlinks, and elimi-
nating this irrelevant information makes the data less complex and improves the performance of the
classifier. Hence, in this work, this irrelevant information and stopwords are removed during pre-
processing. Further, English and Spanish stopwords available at NLTK library1 are used as references
to remove English and Spanish stopwords respectively from the given dataset.

3.1.2. Feature Extraction
The role of feature extraction is to extract relevant features from the given data to train the learning
models. TF-IDF of char n-grams is used to represent English and Spanish text. Char n-grams are
sequences of n consecutive characters in a word and char n-grams in the range (1, 5) are obtained from
the text and converted to TF-IDF vectors using TfidfVectorizer2 .
1
    https://www.nltk.org/search.html?q=stopwords
2
    https://scikit-learn.org/stable/modules/generated/sklearn.feature_extraction.text.TfidfVectorizer.html
Table 3
Hyperparameters and their values used in machine learning models
                                        Model      Hyperparameters          Values
                                                   alpha                         1.0
                                        MNB        fit_prior                   True
                                                   class_prior                None
                                                   C                             1.0
                                                   class_weight            balanced
                                        LSVC
                                                   max_iter                   10000
                                                   random_state                 123
                                        LR         max_iter                    1000
                                                   n_estimators                 100
                                        RF
                                                   random_state                  42


3.1.3. Model Construction
The performance of the learning model relies on the features and the classifier used to carry out
classification. This work utilizes machine learning classifiers (MNB, LR, RF, and ensemble of LSVC,
LR, and RF with majority voting), to distinguish between conspiracy and critical texts in English and
Spanish language. A brief description of the machine learning classifiers is given below:

       • MNB - is a probability-based classifier suitable for text classification with discrete characteristics
         like word frequency counts [13].
       • LinearSVC - used from the Scikit-learn library3 attempts to maximize the distance between
         classified samples by finding a hyperplane.
       • LR - is used to predict the probability of certain classes based on dependent variables and is
         suitable for binary classification task. Further, regularisation approaches in LR classifiers are
         useful for reducing overfitting in high dimensional space [14].
       • RF - is one of the supervised learning algorithms which is flexible and can be adapted easily to
         different situations but it is necessary to build a minimum number of trees in order to classify the
         data [15].
       • Ensemble learning - is a strategy for building a new classifier from several heterogeneous base
         classifiers taking benefit of the strength of one classifier to overcome the weakness of another
         classifier to get better performance for the classification task [16]. In this work, three machine
         learning classifiers (LSVC, LR, and RF) are ensembled with hard voting to distinguish between
         critical and conspiracy texts.

The hyperparameters and their values used in the machine learning models are shown in Table 3.

3.2. Transfer Learning
The technique of transfer learning within the broader field of machine learning utilizes knowledge
gained from one task to improve the performance of another related task. This is realized with the help
of pretrained transformer models which are trained on large unlabeled data and are widely accessible
and applicable to various tasks. The pretrained transformer models are fine-tuned with the given dataset
to fit the models to a particular task or domain. The framework of the proposed transfer learning model
is shown in Figure 2.
   The text is pre-processed to clean and transform the raw text into a consistent format by converting
numeric information to corresponding words, and removing URLs, user mentions, hash tags, and special
characters. Preprocessing is applied to the sentences of the given text to retain the sentence structure
in the text and the preprocessed text is used to fine-tune the transformer models. A brief description of
the transformer models used in this study to fine-tune are given below:
3
    https://scikit-learn.org/stable/modules/generated/sklearn.svm.LinearSVC.html
Figure 2: Framework of the proposed transfer learning model


    • BERT_base4 is a conceptually simple and empirically powerful pretrained language model using
      a Masked Language Modeling (MLM) objective trained on Toronto Book Corpus and Wikipedia
      and exclusively used for tasks involving English texts.
    • English_BERT5 - is a bilingual Legal BERT model trained with 2,000 Dutch and 6,000 English
      legal documents amounting to 12 GB legal text from various areas belonging to legal domain such
      as legislation and court cases. This domain specific BERT has resulted in improved performance
      compared to using standard BERT models for legal tasks.
    • CT_BERT_v26 - is a BERT-large-uncased model pretrained on a corpus of messages from Twitter
      about COVID-19. This model is identical to covid-twitter-bert but trained on more data (40.7M
      sentences and 633M tokens) resulting in higher performances for many downstream applications.
    • EN_RoBERTa7 - is a large multi-lingual language model trained on 12.5TB of filtered Common-
      Crawl data. Based on Facebook’s RoBERTa model, this model is fine-tuned with the conll2003
      dataset in English.
    • ES_BERT8 - BETO: Spanish BERT is trained on the Spanish edition of Wikipedia, the OPUS
      Project, and Spanish books and news articles, and is exclusively used for tasks involving Spanish
      texts.
    • Distil_SpanBERT9 - is a distilled version of SpanishBERT, trained on Spanish text sources, and is
      also exclusively used for tasks involving Spanish texts, but is optimized for efficiency and speed.
    • Spanish_BERT10 - is a sentence-transformers model which maps sentences and paragraphs to a
      768 dimensional dense vector space and can be used for tasks like clustering or semantic search.
    • ES_RoBERTa11 - a variant of RoBERTa is a BERT-based model, specifically tailored for the Span-
      ish language. It is trained on large Spanish text corpora to understand and generate contextually
      relevant representations of words and sentences.

   We employed the above mentioned BERT variants from the Hugging Face library. The hyperpa-
rameter and their values used in the above transfer learning models are shown in Table 4. These
BERT variants are fine-tuned with the pre-processed Train set and is used to train transformer classi-
fier (ClassificationModel) to distinguish between conspiracy and critical texts in English and Spanish
language.

4
  https://huggingface.co/google-bert/bert-base-uncased
5
  https://huggingface.co/Gerwin/legal-bert-dutch-english
6
  https://huggingface.co/digitalepidemiologylab/covid-twitter-bert-v2
7
  https://huggingface.co/FacebookAI/xlm-roberta-large-finetuned-conll03-english
8
  https://huggingface.co/dccuchile/bert-base-spanish-wwm-cased
9
  https://huggingface.co/dccuchile/distilbert-base-spanish-uncased
10
   https://huggingface.co/hiiamsid/sentence_similarity_spanish_es
11
   https://huggingface.co/bertin-project/bertin-roberta-base-spanish
Table 4
Hyperparameter and their values used in transfer learning models
              Model                  Hyperparameter                        Value
                              architectures                                   BertForMaskedLM
                              attention_probs_dropout_prob                                     0.1
                              hidden_size                                                     768
            BERT_base         intermediate_size                                             3072
                              max_position_embeddings                                         512
                              model_type                                                     bert
                              vocab_size                                                   30522
                              architectures                                          BertModel
                              hidden_size                                                     768
                              max_position_embeddings                                         512
          English_BERT        model_type                                                     bert
                              hidden_size                                                     768
                              num_hidden_layers                                                12
                              vocab_size                                                 105879
                              hidden_act                                                     gelu
                              hidden_size                                                   1024
           CT_BERT_v2         intermediate_size                                             4096
                              model_type                                                     bert
                              vocab_size                                                   30522
                              architectures                    XLMRobertaForTokenClassification
                              hidden_act                                                     gelu
           EN_RoBERTa         max_position_embeddings                                         514
                              model_type                                            xlm-roberta
                              vocab_size                                                 250002
                              architectures                                   BertForMaskedLM
                              hidden_act                                                     gelu
                              hidden_size                                                     768
             ES_BERT
                              intermediate_size                                             3072
                              position_embedding_type                                  absolute
                              vocab_size                                                   31002
                              architectures                             DistilBertForMaskedLM
         Distil_SpanBERT      model_type                                               distilbert
                              vocab_size                                                   31002
                              architectures                                          BertModel
                              hidden_act                                                     gelu
          Spanish_BERT        model_type                                                     bert
                              position_embedding_type                                  absolute
                              vocab_size                                                   31002
                              architectures                              RobertaForMaskedLM
                              hidden_act                                                     gelu
           ES_RoBERTa         hidden_size                                                     768
                              max_position_embeddings                                         514
                              vocab_size                                                   50262


4. Experiments and Results
The datasets provided by the organizers of the shared task consisted of only Train set and are highly
imbalanced. Statistics of the datasets are as follows:

    • English dataset: 2,621 samples belong to ’CRITICAL’ class and 1,379 samples belong to ’CON-
      SPIRACY’ class.
    • Spanish dataset: 2,538 samples belong to ’CRITICAL’ class and 1,462 samples belong to ’CON-
      SPIRACY’ class.
Table 5
Performances of the proposed machine learning and transfer learning models on English language Validation set
                                                                                   Macro
                                 Models                    Precision    Recall
                                                                                  F1 Score
                                            MNB               0.84       0.51       0.42
                                            LSVC              0.86       0.87       0.86
                 Machine Learning             LR              0.82       0.79       0.80
                                              RF              0.84       0.80       0.81
                                          Ensemble            0.84       0.82       0.83
                                         BERT_base            0.83       0.82       0.82
                                        English_BERT          0.92       0.89       0.90
                 Transfer Learning
                                        CT_BERT_v2            0.80       0.80       0.80
                                        EN_RoBERTa            0.34       0.50       0.40

Table 6
Performances of the proposed machine learning and transfer learning models on Spanish language Validation set
                                                                                   Macro
                                 Models                    Precision    Recall
                                                                                  F1 Score
                                             MNB              0.82       0.50       0.40
                                             LSVC             0.83       0.83       0.83
                 Machine Learning             LR              0.83       0.77       0.79
                                              RF              0.81       0.75       0.77
                                          Ensemble            0.83       0.79       0.81
                                          ES_BERT             0.92       0.90       0.91
                                        Distil_ESBERT         0.69       0.70       0.69
                 Transfer Learning
                                        Spanish_BERT          0.90       0.87       0.88
                                         ES_RoBERTa           0.78       0.74       0.75


   As the datasets consists of only Train sets, 33% of the Train sets at random are considered as Validation
sets to evaluate the performances of the proposed models for both the languages and the remaining
as the Train sets. Experiments were carried out by training various machine learning models using
TF-IDF of char n-grams in the range (1, 5) and by fine-tuning various BERT variants mentioned above,
to distinguish between conspiracy and critical texts in English and Spanish. The performances of the
proposed models were evaluated on the Validation set based on macro F1 score and the performances
are shown in Tables 5 and 6 for English and Spanish datasets respectively.
   The results shown in Tables 5 and 6 illustrate that transfer learning models have performed better
than machine learning models. As the shared task participants were allowed to submit the predictions
of only two models on the Test sets, we fine-tuned English_BERT and EN_RoBERTa with the complete
English Train set and Spanish _BERT and ES_RoBERTa with the complete Spanish Train set and the
predictions of these models on English and Spanish Test sets submitted to the organizers were evaluated
based on MCC scores. MCC is a metric used to evaluate the quality of binary classifications especially
with imbalanced datasets. The MCC value ranges from -1 to +1, where +1 indicates perfect prediction, 0
indicates no better than random prediction, and -1 indicates total disagreement between prediction and
observation. MCC provides a balanced and comprehensive measure of model’s performance, considering
all types of classification errors. MCC scores are calculated using the following formula:
                                     (𝑇 𝑃 × 𝑇 𝑁 ) − (𝐹 𝑃 × 𝐹 𝑁 )
                    MCC = √︀
                            (𝑇 𝑃 + 𝐹 𝑃 )(𝑇 𝑃 + 𝐹 𝑁 )(𝑇 𝑁 + 𝐹 𝑃 )(𝑇 𝑁 + 𝐹 𝑁 )

where:
    • 𝑇 𝑃 (True Positives) - number of correct positive predictions,
    • 𝑇 𝑁 (True Negatives) - number of correct negative predictions,
    • 𝐹 𝑃 (False Positives) - number of incorrect positive predictions,
Table 7
Performances of English_BERT and Spanish_BERT models on Test set in English and Spanish - models submitted
to the shared task
                                            MACRO               F1                F1
    Language         Model         MCC                                                      POSITION
                                           F1 SCORE CONSPIRACY CRITICAL
     English     English_BERT     0.7162     0.8538           0.7994            0.9082          61
     Spanish     Spanish_BERT 0.6293         0.8060           0.7363            0.8756          36


    • 𝐹 𝑁 (False Negatives) - number of incorrect negative predictions.
   Among the two transfer learning models submitted to the shared task, English_BERT and Span-
ish_BERT models obtained MCC scores of 0.7162 and 0.6293 for English and Spanish texts securing
61st and 36th position respectively. The performances of these models is shown in the Table 7. The
low performances of fine-tuned English_BERT and Spanish_BERT models could be attributed to the
following reasons:
    • The given datasets are highly imbalanced with approximately 2/3 of the total samples belonging
      to ’CRITICAL’ class and 1/3 belonging to ’CONSPIRACY’ class in both the languages. The highly
      imbalanced data will significantly impact the models’ performance with a bias towards majority
      class.
    • English_BERT designed for both Dutch and English may potentially reduce its effectiveness for
      purely English tasks. Further, domain-specific models like English_BERT might not generalize
      well outside their specialized contexts.
    • Spanish_BERT model might be more suited for sentence similarity tasks rather than classification.
Further, differences in pre-training data, fine-tuning processes, and the values of hyperparameters used
in the models could also contribute to the disparity in the performances of the proposed models.


5. Conclusion and Future Work
In this paper, we - team MUCS, describe the models submitted to Subtask-1: ’Distinguishing between
critical and conspiracy texts’ of the shared task "Oppositional thinking analysis: Conspiracy theories vs
critical thinking narratives" at ’PAN 2024’, to distinguishing between critical and conspiracy texts in
English and Spanish. Experiments are carried out with TF-IDF of char n-grams in the range (1, 5) to
train several machine learning classifiers and several BERT variants are fine-tuned with the English
and Spanish Train sets in transfer learning models, to distinguish the given unlabeled English and
Spanish text as ’CONSPIRACY’ or ’CRITICAL’. As the shared task participants were allowed to submit
the predictions of only two models on the Test set, we fine-tuned English_BERT and EN_RoBERTa
with the complete English Train set and Spanish_BERT and ES_RoBERTa with the complete Spanish
Train set and the predictions of these models on English and Spanish Test sets were submitted to the
organizers for evaluation. Among these two models, English_BERT and Spanish_BERT obtained MCC
scores of 0.7162 and 0.6293 for English and Spanish texts securing 61st and 36th position respectively.
As the given datasets are imbalanced, suitable text augmentation techniques followed by efficient text
representation methods and context-aware models to distinguish between the two forms of oppositional
thinking will be explored further.


References
 [1] H. Sharp, Oppositional Ideas, Not Dichotomous Thinking: Reply to Rorty, in: Political Theory,
     Sage Publications Sage CA: Los Angeles, CA, 2010, pp. 142–147.
 [2] A. Giachanou, B. Ghanem, P. Rosso, Detection of Conspiracy Propagators using Psycho-Linguistic
     Characteristics, in: Journal of Information Science, SAGE Publications Sage UK: London, England,
     2023, pp. 3–17.
 [3] K. M. Douglas, R. M. Sutton, What are Conspiracy Theories? A Definitional Approach to their
     Correlates, Consequences, and Communication, in: Annual review of psychology, volume 74,
     Annual Reviews, 2023, pp. 271–298.
 [4] A. A. Ayele, N. Babakov, J. Bevendorff, X. B. Casals, B. Chulvi, D. Dementieva, A. Elnagar, D. Freitag,
     M. Fröbe, D. Korenčić, M. Mayerl, D. Moskovskiy, A. Mukherjee, A. Panchenko, M. Potthast,
     F. Rangel, N. Rizwan, P. Rosso, F. Schneider, A. Smirnova, E. Stamatatos, B. Stein, M. Taulé,
     D. Ustalov, X. Wang, M. Wiegmann, S. M. Yimam, E. Zangerle, Overview of PAN 2024: Multi-
     Author Writing Style Analysis, Multilingual Text Detoxification, Oppositional Thinking Analysis,
     and Generative AI Authorship Verification - Condensed Lab Overview, in: Experimental IR
     Meets Multilinguality, Multimodality, and Interaction. Proceedings of the Fifteenth International
     Conference of the CLEF Association CLEF-2024, 2024.
 [5] J. Moffitt, C. King, K. M. Carley, Hunting Conspiracy Theories during the COVID-19 Pandemic,
     Social Media+ Society 7 (2021) 20563051211043212.
 [6] S. G. Thornton, R. M. Romano, Beyond Oppositional Thinking: Radical Respect., in: Philosophical
     Studies in Education, volume 38, ERIC, 2007, pp. 199–209.
 [7] J. Bevendorff, X. B. Casals, B. Chulvi, D. Dementieva, A. Elnagar, D. Freitag, M. Fröbe, D. Ko-
     renčić, M. Mayerl, A. Mukherjee, A. Panchenko, M. Potthast, F. Rangel, P. Rosso, A. Smirnova,
     E. Stamatatos, B. Stein, M. Taulé, D. Ustalov, M. Wiegmann, E. Zangerle, Overview of PAN 2024:
     Multi-Author Writing Style Analysis, Multilingual Text Detoxification, Oppositional Thinking
     Analysis, and Generative AI Authorship Verification, in: Experimental IR Meets Multilinguality,
     Multimodality, and Interaction. Proceedings of the Fourteenth International Conference of the
     CLEF Association (CLEF 2024), Lecture Notes in Computer Science, Springer, Berlin Heidelberg
     New York, 2024, pp. 3–10.
 [8] M. Moosleitner, B. Murauer, On the Performance of Different Text Classification Strategies on
     Conspiracy Classification in Social Media., in: MediaEval, 2021.
 [9] K. Tahat, A. Mansoori, D. N. Tahat, M. Habes, R. Alfaisal, S. Khadragy, S. A. Salloum, Detecting
     Fake News during the COVID-19 Pandemic: A SEM-ML Approach, in: Comput. Integr. Manuf.
     Syst, 2022, pp. 1554–1571.
[10] Y. Peskine, P. Papotti, R. Troncy, Detection of COVID-19-Related Conpiracy Theories in Tweets us-
     ing Transformer-Based Models and Node Embedding Techniques, in: MediaEval 2022, Multimedia
     Evaluation Workshop, 12-13 January 2023, Bergen, Norway, 2023.
[11] A. Recordare, G. Cola, T. Fagni, M. Tesconi, Unveiling Online Conspiracy Theorists: a Text-Based
     Approach and Characterization, in: arXiv preprint arXiv:2405.12566, 2024.
[12] M. Ghasemizade, J. Onaolapo, Developing a Hierarchical Model for Unraveling Conspiracy
     Theories, in: EPJ Data Science, Springer Berlin Heidelberg, 2024, p. 31.
[13] P. Harjule, A. Gurjar, H. Seth, P. Thakur, Text Classification on Twitter Data, in: 2020 3rd
     International Conference on Emerging Technologies in Computer Engineering: Machine Learning
     and Internet of Things (ICETCE), IEEE, 2020, pp. 160–164.
[14] J. Friedman, T. Hastie, R. Tibshirani, Additive Logistic Regression: A Statistical View of Boosting
     (With Discussion and a Rejoinder by the Authors), in: The annals of statistics, Institute of
     Mathematical Statistics, 2000, pp. 337–407.
[15] M. Huljanah, Z. Rustam, S. Utama, T. Siswantining, Feature Selection using Random Forest
     Classifier for Predicting Prostate Cancer, in: IOP Conference Series: Materials Science and
     Engineering, IOP Publishing, 2019, p. 052031.
[16] M. Li, P. Xiao, J. Zhang, Text Classification based on Ensemble Extreme Learning Machine, in:
     arXiv preprint arXiv:1805.06525, 2018.