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Emotional Stimuli AND Social Categorisation


A study conducted by researchers at the Department of Psychology at Sapienza University in collaboration with the Santa Lucia Foundation has analysed how based on changes in our skin temperature changes, emotional stimuli drive us to include or exclude others from our social sphere.

The study is based on the fact that skin temperature is affected by changes in our muscles and microcirculation, which are controlled by the vegetative nervous system (also known as the autonomic nervous system) whose activity is largely independent of our will.
The project, coordinated by Professor Salvatore Maria Aglioti from the Sapienza Department of Psychology has been published in Proceedings of the Royal Society B: Biological Sciences Journal.

To demonstrate the association between changes in facial temperature and the way in which we perceive individuals around us, researchers presented participants with emotional stimuli of which they were more or less conscious, known respectively as supraliminal and subliminal stimuli. This led to the discovery of the physiological reaction thanks to a thermal camera, a device capable of precisely measuring bodily heat emission through infrared signal recording systems (Infrared Thermal Imaging).

The research project has revealed a tendency to categorize/perceive the faces of strangers as close to our social circle in the presence of positive stimuli and to consider them more distantly – or excluded - as a result of negative stimuli. Social categorization is the process by which we codify other people as in-group versus out-group based on different elements (ethnicity, religion, ideology). It is a voluntary cognitive mechanism strongly influenced by emotions.

"The results of this study,” explains Maria Serena Panasiti, a researcher at the Sapienza Department of Psychology “are relevant to understanding intergroup dynamics and physiological indexes associated with them, such as emotions, perceptual awareness of stimuli and how the activation of the vegetative nervous system greatly affects the tendency to categorize others as us vs. them."

The research was supported by a PRIN Grant (Research Projects of Relevant National Interest, Edit. 2015, Prot. 20159CZFJK) and European Funds (Horizon 2020-SESAR-2015-1-MOTO: The embodied reMoTe Tower, Project Number 699379).

References: Ponsi G, Panasiti MS, Rizza G, Aglioti SM. Thermal facial reactivity patterns predict social categorization bias triggered by unconscious and conscious emotional stimuli. Proc Biol Sci. 2017 Aug 30; 284 (1861). pii: 20170908. DOI: 10.1098 / rspb.2017.0908.