Abstract

AREVALO-PACHON, Guillermo  and  CRUZ, Julio Eduardo. Contagious laughter as a provocative vocalization of facial and electromyographic expressions related to positive emotions in listeners. Act.Colom.Psicol. [online]. 2021, vol.24, n.2, pp.45-58.  Epub Oct 13, 2021. ISSN 0123-9155.  https://doi.org/10.14718/acp.2021.24.2.5.

Despite its relevance for the understanding of vocal emotional expression, the study of contagious laughter is in its early stages of research and neither its nature nor the nature of the responses it provokes have not yet been established. The purpose of this study was to determine whether the acoustic stimuli of contagious laughter, in addition to generating laughter or smiling behaviors, elicit in listeners the facial, electromyographic and heart expressions of a positive emotion. To this end, 60 university students of both sexes, aged between 18 and 30 years participated in an intrasubject experimental design with measurements in the baseline condition and in exposures to different contagious laughter stimuli, where three hypotheses were tested comparing facial expressions of joy (measured with the FaceReader software), electromyographic amplitude (EMG) of the zygomaticus major muscle (measured with the Biopac EMG-100 module) and RR intervals as indicators of heart rate (measured with the Biopac ECG-100 module) between the different conditions. As a result, significant differences were found in the percentages of facial expressions ofjoy and zygomatic EMG amplitude when comparing the baseline and stimulus conditions of more contagious laughter, and more and less contagious laughter. However, no significant differences were found in the R-R intervals in any of the compared conditions. In conclusion, the positive emotional nature of laughter / smile caused by contagious laughter stimuli and the proportionality between the intensity of the facial expressions and EMG responses elicited by this laughter and the perceived degree of contagiousness of laughter were verified.

Keywords : laughter; emotional contagiousness; joy; facial expression; facial electromyographynt.

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