Research / Investigación

Category learning, categorical perception and language.
How is it that our nervous systems vertiginously extract the relevant information out of the world's "booming, buzzing confusion" (sic. William James) to know what is what and what to do with what? To successfully interact with the world, different organisms learn to sort objects and instances in the world, detecting  shared features among objects towards which we can act in the same way and ignoring those characteristics that are not relevant for interaction. This process is called categorization. Moreover, humans have evolved a system of symbols through which we can refer to these learned categories (even when their referents are not present) and share them with other fellow humans, and what we categorize and name depends on our geographical, cultural and social environment. What changes in our brain when we start sorting and naming the world according to our contexts? Do we see and experience the world differently as a result of these processes? 

My doctoral thesis, titled "How and why does category learning cause categorical perception?" combined psychophysics, electroencephalographic techniques and computational models to assess how learning new categories through sensorimotor interaction changes our neurocognitive processes, focusing on the effect of learning new categories on perception.  The neural and behavioral findings of our experimental work support the idea that learning new categories change early perceptual processes in the brain, making us perceive things within the same category as more similar and things belonging to different categories as more different and the data from our computational models suggest that these changes arise thanks to dimensional reduction: When we learn to detect those features or characteristics that are relevant to categorize, our brain systems prioritize them over other perceptual information, "shrinking" the stimulus dimensional space and generating a "feature filter" that will allow us to categorize effortlessly and automatically in the future.  My thesis brings these levels of explanation together with linguistics and cognitive science to elaborate on how systems of categories (largely conveyed by language and culture)  have an effect on the way we experience the world. 

Related publications and conference presentations.

Pérez Gay, F., House, L., Sicotte, T, Harnad, S. (2021). Alpha desynchronization in the occipital cortex during category learning as a neural correlate of Learned Categorical Perception. Data Blitz & Poster presentation. Cognitive Neuroscience Society 24th Annual meeting (Virtual). March 13-16, 2021.

Pérez-Gay, F., Sicotte, T., Thériault, C., & Harnad, S. (2019). Category learning can alter perception and its neural correlates. PloSONE (14), e0226000. https://doi.org/10.1371/journal.pone.0226000

Pérez-Gay, F., Labrecque, D., Frak, V. (2019) Electrophysiological correlates of language-induced motor activity: Combining cognitive Event Related Potentials and the Grip Force Sensor. Brain and Cognition (135), https://doi.org/10.1016/j.bandc.2019.05.010

Pérez Gay, F., Thériault, C., Kang, X., Rivas, D., Sicotte, T., Harnad, S. (2017). Poster presentation. Category Learning Generates Categorical Perception: Behavioral, Neural and Computational Aspects. Cognitive Neuroscience Society 24th meeting. Hyatt Regency, San Francisco, Cal., USA. March 25-28, 2017. https://tinyurl.com/ea7ue5d2

Li, M., Rivas, D., Pérez-Gay, F., Sicotte, T., & Harnad, S. (2018). Acquisition of categorical perception of Mandarin tone. The Journal of the Acoustical Society of America. 144, 1867-1868. DOI: 10.1121/1.5068214. https://asa.scitation.org/doi/10.1121/1.5068214

Pérez-Gay, F., Thériault, C., Gregory, M., Sabri, H, Rivas, D. & Harnad, S. (2017). How and why does category learning cause categorical perception?  International journal of comparative psychology, 30 (0).  https://escholarship.org/uc/item/8rg6c087

Social Categorization, Theory of Mind and Narrative Fiction
My doctoral work fueled my interest to look for similar effects in social categorization and its impact on the way we perceive, understand and treat other people. In my postdoctoral project, I have led the creation of a new, multicultural face database to investigate the interactions between social categorization—the classification of others as within or outside of one’s own group—and Theory of Mind – the capacity to attribute mental states to others. In parallel, experiments are being run to explore whether the effects arising from this interaction can be altered by reading fiction. As part of this line of research, I have led the development and validation of a new multicultural face database of 93 different facial expressions. This project is important because it will provide the first systematic assessment of the effects of social categorization on Theory of Mind as well as an experimental evaluation of the power of fiction to reduce prejudice by fostering the understanding of others outside our social group. 

Relevant publications and conference presentations

Pérez-Gay, F.,  Touté, L., Leos, H.,  (2023). Using fiction to enhance empathy accross ethnic groups: An exploratory study. Society for Personality and Social Psychology. Social Cognition Preconference.  Atlanta, Georgia. Febrary 22-26, 2023. https://fictionsocialcatandtom.tiiny.site/

Pérez-Gay, F. & Touté, L. (2022, forthcoming). The neuroscience of literary fiction: A bridge between the biomedical sciences and the humanities. In D. Laforest, E. Mihelakis & L. Toth (Eds.) Toward Embodied Narratives in the Health Humanities and Literary Studies . University of Toronto Press. Forthcoming.

Pérez-Gay F., Leone, O., Solomonova, E., Gold, I. (2022). Transcultural mindreading: Building a new database of Facial Expressions with actors of diverse ethnicities to assess social cognition. Cognitive Science Society 2022. Toronto, Canada. July 29th, 2022. https://escholarship.org/uc/item/8038q79w

Psychosocial consequences of the COVID-19 pandemic

In 2020, after the COVID-19 pandemic hit, I joined international efforts to study the socio-psychological consequences of the pandemic and associated government measures through a) the COVIDiSTRESS project, which gathered a global dataset (N=173,426) for the  cross-cultural study of psychological and behavioural responses to the pandemic, b) the “COVID beliefs and mental health project”, based at McGill university, where we studied the association between mental health symptoms, conspiracy ideation and fear of contagion, c) the “COVID impacts in social cognition”, a series of experiments studying the impact of face masks and virtual interaction in Theory of Mind and social interactions and d) The McGill "Overcoming Vaccine Hesitancy project", in which we explore psychosocial factors associated to vaccine hesitancy and explore strategies to overcome them. 

Relevant publications and conference presentations

Leos, H., Gold, I. & Pérez-Gay F. (2023) Face masks negatively skew theory of mind judgements. Sci Rep 13, 4950 (2023). https://doi.org/10.1038/s41598-023-31680-y 

Solomonova, E., Pérez-Gay F., Gold, I. (2022). Distressing nightmares and bad dreams during the COVID-19 pandemic are associated with depressive symptoms, somatic symptoms and delusional ideation. Poster presentation.  World Sleep Congress 2022. Rome, Italy, March 15th, 2022. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9300190/

Lieberoth, A., Lin, S. Y., Stöckli, S., Han, H., Pérez-Gay, F., & COVIDiSTRESS global survey consortium (2021). Stress and worry in the 2020 coronavirus pandemic: relationships to trust and compliance with preventive measures across 48 countries in the COVIDiSTRESS global survey. Royal Society open science, 8(2), 200589. https://doi.org/10.1098/rsos.200589

Yamada, Y., Ćepulić, DB., Coll-Martín, T, Pérez-Gay. F., & COVIDiSTRESS global survey consortium (2021). COVIDiSTRESS Global Survey dataset on psychological and behavioural consequences of the COVID-19 outbreak. Scientific Data 8, 3. https://doi.org/10.1038/s41597-020-00784-9

Contreras-Ibáñez, C., Flores, R., Reynoso-Alcántara, V. Pérez-Gay, F., Castro, C. & Martínez, L. (2020). Socioeconomic and situational conditions associated with stress at the start of the COVID-19 pandemic. Condiciones psicosociales y situacionales asociadas al estrés al inicio de la pandemia por COVID-19. Entorno UDLAP, edición especial, 102-119.