In a groundbreaking advancement at the intersection of neuroscience, psychology, and affective science, researchers have unveiled compelling evidence demonstrating that the electrical stimulation of smiling muscles can significantly modulate visual processing and emotional perception. Published in Communications Psychology in 2025, this study, spearheaded by Baker, Ngo, Efthimiou, and colleagues, reveals that artificially activating the muscles responsible for smiling not only alleviates the cognitive burden required to process visual stimuli but also enhances the viewer’s perception of happiness, even when observing faces that are emotionally neutral. These insights illuminate the intricate feedback loops between facial motor activity and affective perception, challenging longstanding models of emotion recognition and cognitive load in social contexts.
Traditional theories of emotion perception have heavily emphasized the significance of visual cues and contextual information in interpreting facial expressions. However, this new research posits that facial motor activations—specifically, the activation of muscles engaged in smiling—can exert a top-down influence, effectively recalibrating the observer’s neural mechanisms involved in visual processing. By employing transcutaneous electrical stimulation targeted at the zygomaticus major muscle, which is predominantly responsible for the elevation of the corners of the mouth during a smile, researchers were able to induce subtle muscular activations without overtly altering facial expressions. This method allowed for the isolation of facial muscle activity effects on the viewer’s cognitive processing, thereby providing a unique window into sensorimotor-affective integration.
The experimental paradigm utilized functional neuroimaging alongside behavioral assessments to track changes in both brain activity and subjective affective ratings while participants viewed images of emotionally neutral faces. The methodology was meticulous: participants underwent controlled electrical stimulation sessions and compared to sham stimulation controls. Remarkably, neural markers associated with visual processing efficiency, particularly within the occipitotemporal cortex, showed decreased activation thresholds during muscle stimulation. This suggests that smiling muscle activation reduces the neural resources required to decode facial stimuli, thereby lessening the visual processing load.
Moreover, participants reported higher happiness ratings in response to the neutral faces during sessions involving electrical stimulation of their smiling muscles. These findings provide robust empirical support for the embodied cognition framework, positing that bodily states and motor activity influence perception and emotion in a bidirectional manner. The observed enhancement in positive emotional perception underscores a form of somatic feedback whereby activating smiling muscles predisposes the brain to infer greater happiness in otherwise emotionally ambiguous stimuli.
The implications of these findings extend beyond theoretical neuroscience, offering practical insights for clinical and therapeutic applications. Emotional dysregulation, often manifesting in affective disorders such as depression and anxiety, can be linked to impairments in emotion perception and social cognition. The demonstrated ability to modulate emotional experience through peripheral stimulation of facial musculature holds promise for novel, non-invasive interventions aimed at improving affective processing and emotional wellbeing.
It is particularly intriguing to consider the temporal dynamics underlying this effect. The speed at which smiling muscle stimulation influenced both neural processing and subjective ratings suggests a rapid sensorimotor feedback mechanism, which may operate unconsciously and prior to higher-order cognitive appraisal. This raises fundamental questions regarding the hierarchy of emotional perception and the extent to which peripheral physiological signals inform central nervous system activity related to social cognition.
Additionally, this research provides a fresh perspective on the role of microexpressions and subtle facial movements in everyday social interactions. Given that smiling is a universal nonverbal cue associated with positive affect, the activation of these muscles may serve as a physiological shortcut facilitating social bonding and empathy. Electrical stimulation thus serves as a controlled mimicry of natural smiling muscle activity, highlighting its functional importance in emotional communication.
The technological approach also merits attention. Using low-intensity transcutaneous electrical nerve stimulation (TENS) patches positioned strategically on the face, the researchers navigated challenges of safety, participant comfort, and stimulation precision. This careful balancing act underscores the increasing interdisciplinary sophistication in experimental paradigms, merging bioengineering with cognitive psychology to probe embodied affective phenomena.
Furthermore, the study navigates complex questions surrounding causality in embodied emotion theories. While prior observational studies have identified correlations between smiling and positive affect, this research establishes causative links by experimentally manipulating facial motor activity and observing downstream changes in perception. This experimental rigor marks a critical advancement in disentangling the intricate feedforward and feedback loops within affective neuroscience.
While the current focus rested on smiling muscles and happiness perception, the methodological framework invites expansions into other facial muscle groups and a spectrum of emotions. For example, stimulating muscles involved in frowning could explore the converse effect on negative emotion perception and cognitive load, deepening our understanding of sensorimotor contributions across emotional valence.
Considering the broader cognitive framework, this study complements existing models of predictive coding, where the brain uses incoming sensory data to generate hypotheses about the environment. Smiling muscle activation may modify these predictions, biasing perceptual inference toward more positive emotional categorizations. Such interactions emphasize the active role of the body in shaping mind and perception.
From a social neuroscience standpoint, this research provides a physiological substrate for phenomena such as emotional contagion and mimicry. By showing that induced facial muscle activation lowers barriers to perceiving happiness, it supports theories that shared bodily states facilitate resonance and understanding in social contexts. These insights could inform socially assistive technologies and interventions aimed at enhancing empathy and rapport.
This pioneering work also invites ethical reflection regarding the use of neuromodulation and peripheral stimulation to influence mood and perception. While promising, responsible application requires nuanced consideration of autonomy, consent, and the longitudinal effects of such interventions. Ongoing research must balance efficacy with safety and psychological implications.
In conclusion, Baker and colleagues’ study redefines the nexus of facial motor activity and emotional perception, offering a compelling demonstration that the electrical stimulation of smiling muscles reduces visual processing load and enhances happiness perception, even in neutral faces. This convergence of neuroengineering, psychology, and social neuroscience charts a transformative path for both theoretical understanding and practical modalities to enrich human emotional experience. The subtle interplay between muscle activation and perceptual interpretation underscores the profound embodiment of human affect—what our faces do can profoundly shape what we see and feel in others.
Subject of Research: Electrical stimulation of smiling muscles and its effects on visual processing load and happiness perception in neutral faces.
Article Title: Author Correction: Electrical stimulation of smiling muscles reduces visual processing load and enhances happiness perception in neutral faces.
Article References:
Baker, J., Ngo, H., Efthimiou, T.N. et al. Author Correction: Electrical stimulation of smiling muscles reduces visual processing load and enhances happiness perception in neutral faces. Commun Psychol 3, 111 (2025). https://doi.org/10.1038/s44271-025-00297-4
Image Credits: AI Generated
