This study is part of a research project aimed at investigating the relationship between language writing skills and the development of critical thinking (CT) cognitive skills in public high school students, aiming to contribute to the following research question: How does writing and comprehension skills in one's mother tongue contribute to the cognitive skills of critical thinking in high school students? We will focus on the links between writing skills and critical thinking, employing a cognitive framework to integrate data from social contexts, and behavior, all the while recording neural activity using electroencephalography (EEG).

Facione (1990, p. 2) assumes “critical thinking to be purposeful, self-regulatory judgment which results in interpretation, analysis, evaluation, and inference, as well as explanation of the evidential, conceptual, methodological, criteriological, or contextual considerations upon which that judgment is based”. CT is associated with academic success (Halpern, 2014), better informed decision making (Butler, 2012), and better professional opportunities (Brotherton, 2011; Weng,2015). Despite its importance, many students present insufficient levels of CT (Flores et al, 2012; Carrithers et al., 2008; Harasym et al., 2008). 

In secondary education and in young students, there are relatively few studies on CT (Deniz, 2019; Fung, 2017; Liang & Fung, 2021; Lopes et al., 2018; Uğurlu, 2010). This can be explained, perhaps, by the observation that CT is usually considered a higher-order skill associated with adult thinking, higher education, scientific knowledge, and the workplace (Bağ & Gürsoyb, 2021). However, according to Piaget’s Theory of Cognitive Development, students in secondary education typically develop the cognitive capacities necessary for critical thinking, as they enter the formal operational stage. 

A literature review on these topics reveals studies that have assessed the CT level of participants (Reid & Chin, 2021), and explored  correlations between CT and language proficiency, motivation, and academic success (Altay, 2013; Bagheri, 2015), but generally in the context of a second language. In the context of the mother tongue, researchers have found high levels of some higher-order skills involved in critical thinking such as analytical thinking and problem-solving skills (Arum & Roksa, 2011; Demir, 2022). Another focus has been the impact of external factors on students’ development of critical thinking such as different pedagogies (Fung, 2017; Liang & Fung, 2021), the role of the parents' educational level (Ekinci & Aybek, 2010), and reading habits (Çelik et al., 2015; Gökkuş & Delican, 2016; Koçak et al., 2015 for higher education).

Research on neuroscience of creativity has focused on spectral analyses in the alpha band frequency, where task-related increases (synchronization) in the lower alpha band have been associated to attentional effort, while increases in the upper alpha band to specific task requirements as semantic processing (Fink et al., 2014). These results also suggest that increased alpha activity is associated with divergent thinking (Mölle et al., 1999; Jauk et al., 2012), implicating this activity as a marker of a state of focused attention and mental processing required for creativity tasks (Fink et al., 2014).

To the best of our knowledge no studies have evaluated brain activity through spectral analyses in the alpha band during a natural task using the Critical Thinking Test (TPC). Therefore, the main goal of this study is to assess alpha band power in the lower (8-10 Hz) and upper (10-12 Hz) alpha bands to understand whether this activity is sensitive to the cognitive demands of the cognitive activities employed in the TPC.

This study will address the following research questions: (i) How do students perform in CT tasks across Grades 10, 11, and 12? (ii) How does writing proficiency influence CT development? (iii) What are the neural correlates of CT and writing, as assessed through EEG?

A cross-sectional mixed-methods design will be employed, combining a standardized CT test [Teste de Pensamento Crítico (TPC), Lopes et al., 2018, a structured writing assessment, and EEG analyses. The study sample comprises 75 high school students, divided into three cohorts. EEG will be used to examine spectral alpha-band oscillations while participants engage in CT tasks, providing insights into cognitive load and neural activation patterns. Additionally, behavioral data will be analyzed to examine correlations between writing quality, coherence, and CT scores. The study will be conducted in public high schools in Lisbon (Portugal). The 75 participants will be assessed using the TPC test (Lopes et al., 2018) and a structured written assessment, graded according to national standards (IAVE, 2022). Writing samples will be analyzed by trained research team members for linguistic complexity, argument structure, and coherence. A subset of 12 students (four per grade level) will participate in EEG experiments. EEG recordings will capture neural oscillations during the CT task, focusing on spectral analyses of alpha-band activity. Participants will respond to open-ended CT questions while EEG signals are recorded, allowing for real-time neural monitoring. Additional behavioral markers, including reaction time and response accuracy, will be collected. Statistical analyses will include Structural Equation Modeling (SEM) and Latent Growth Curve Modeling to track CT progression. EEG data will be analyzed using spectral decomposition techniques to examine cognitive engagement and effort. Ethical considerations include informed consent, participant anonymity, and adherence to data protection guidelines.

This study aims to contribute to educational neuroscience by identifying neural markers of CT, evaluating the impact of writing proficiency on cognitive growth, and proposing evidence-based strategies for curriculum enhancement. The findings will provide insights for policymakers and practitioners on how to integrate writing tasks into CT-focused instruction. Expected outcomes include: Identification of key writing skills that enhance CT development. Mapping EEG activity patterns associated with different CT skills. Longitudinal analysis of CT growth through written expression. Pedagogical recommendations for integrating writing-focused CT instruction. Insights into cognitive load and neural engagement during writing and CT tasks. Findings will contribute to an interdisciplinary understanding of how language skills shape cognitive development, supporting evidence-based interventions for high school education. This study will also inform teacher training programs, emphasizing the role of structured writing tasks in fostering higher-order thinking skills.

Bağ, H. K., & Gürsoyb, E. (2021). The Effect of Critical Thinking Embedded English Course Design to The Improvement of Critical Thinking Skills of Secondary School Learners. Thinking Skills and Creativity, 41,100910 Bagheri, F. (2015). The Relationship between Critical Thinking and Language Learning Strategies of EFL Learners. Journal of Language Teaching and Research, 6 (5), 969-975 Demir, E. (2022). An examination of high school students’ critical thinking dispositions and analytical thinking skills. Journal of Pedagogical Research, 6(4), 190-200. https://doi.org/10.33902/JPR.202217357 Fink, A. & Benedek, M. (2014). EEG alpha power and creative ideation. Neurosci. Biobehav. Rev. 44(100), 111-23. https://doi.org/10.1016/j Flores, K. L., Matkin, G. S., Burbach, M. E., Quinn, C. E., & Harding, H. (2012). Deficient Critical Thinking Skills among College Graduates: Implications for leadership. Educational Philosophy and Theory, 44, 212-230. https://doi.org/10.1111/j.1469- 5812.2010.00672.x Fung, D. (2017). The pedagogical impacts on students’ development of critical thinking dispositions: Experience from Hong Kong secondary schools. Thinking Skills and Creativity, 26, 128-139 Halpern, D. F. (2014). Thought and knowledge: An introduction to critical thinking (5th ed). Psychology Press. Harasym, P. H., Tsai, T. C., Hemmati, P. (2008). Current trends in developing medical students' critical thinking abilities. Kaohsiung J Med Sci., 24(7), 341-55. https://doi.org/ 10.1016/S1607-551X(08)70131-1 Instituto de Avaliação Educativa [IAVE]. (2022). Exame Final Nacional de Português. 12o ano de escolaridade. Decreto-Lei n.o 55/2018, de 6 de julho | Decreto-Lei n.o 27- B/2022, de 23 de março Jauk, E., Benedek, M., Neubauer, A.C. (2012). Tackling creativity at its roots: Evidence for different patterns of EEG alpha activity related to convergent and divergent modes of task processing. International Journal of Psychophysiology, 84, 219– 225 Koçak, B., Kurtlu, Y., Ulaş, H., & Epçaçan, C. (2015). Examining of the elementary class teachers’ critical thinking levels and their attitudes towards reading. Ekev Akademi Journal, 61(61), 211-228 Liang, W. & Fung, D. (2021). Fostering critical thinking in English-as-a-second-language classrooms: Challenges and opportunities. Thinking Skills and Creativity, 39, 100769 Lopes, J., Silva, H., & Morais, E. (2018). Test de pensamiento crítico para estudiantes de enseñanza básica y secundaria. Revista de Estudios e Investigación en Psicología y Educación, 5(2), 82-91. Mölle, M., Marshall, L., Wolf, B., Fehm, H.L., Born, J. (1999). EEG complexity and performance measures of creative thinking. Psychophysiology, 36, 95–104