Curriculum
Neuroscience, Technology, and Society, XXXIV series
Grant sponsor
STARS Grant
Supervisor

Giuseppe Sartori
Co-supervisor
s
Fabio Aiolli, Cristina Scarpazza (esperto esterno)

Project: Lie to me: processing and detection of spontaneous and posed emotional facial expressions
Full text of the dissertation book can be downloaded from: https://www.research.unipd.it/handle/11577/3459406

Abstract: Facial expressions are the most effective and reliable indicator of emotional states. However, people are adept at modulating and falsifying their emotional expressions according to their needs, completely changing the observer’s perception and reaction. A new validated dataset displaying more than 1450 clips of both spontaneous and posed emotional facial expressions was created for a dual purpose: discriminate spontaneous and posed emotions according to the facial movements (detection section) and investigate how the brain extracts the genuineness of emotional expressions (perception section). In the detection part, Machine Learning models were applied to the clips in order to discriminate spontaneous from posed emotion automatically. Results yielded high accuracies in genuineness discrimination (up to 84.4% accuracy). Moreover, for the first time, the 3-D motion analysis was applied to the study of spontaneous and posed dynamic facial expressions of happiness to detect subtle movements in terms of space, time, and speed. Results revealed that the mouth widening and the speed of smiles are greater in posed than spontaneous happiness. In the perception section, time-frequency EEG analysis was used to compare the perception of three spontaneous and posed emotional facial expressions: happiness, disgust, and fear. Overall, strong differences in both the timing and the topography of the canonical EEG bands were observed, revealing how spontaneous and posed emotions are processed differently in our brains. In particular, compared to genuine happiness, posed happiness revealed increased delta and theta power at the onset and offset of the facial expressions over frontal sites. Compared to posed fear, genuine fear elicits an increase in alpha and beta bands followed by an increase in theta activity. Finally, for facial expressions of disgust, we found an early increased theta, alpha, and beta activity for the posed expressions, followed by increased activity in alpha and beta bands during the perception of genuine disgust. The implications and applications of these studies are discussed in light of the state of art of lie detection, psychology of emotions, and th