Document Type
Article
Publication Date
9-2026
Publication Title
Scientific Reports
Abstract
Speaking and gesturing are fundamental aspects of human communication that commonly occur while main- taining upright posture. Although speech and postural control are known to compete for shared motor-cognitive resources, it remains unclear how co-speech gestures affect balance control and their underlying neural mecha- nisms. Using combined behavioral and neuroimaging approaches, we investigated whether co-speech gestures interfere with concurrent postural control, whether this interference depends on the spatial reference frame (egocentric vs. allocentric), and whether dual-task costs arise from competing motor demands, overlapping cog- nitive processes, or both. Forty-one right-handed adults (25.9 ± 6.8 years) maintained posture—monitored via a wearable Inertial Measurement Unit (IMU) sensor—while performing co-speech and no-speech gestures with right and left hands from allocentric or egocentric perspectives. Functional near infrared spectroscopy (fNIRS) was applied to measure cortical oxygenation in bilateral pre- and postcentral areas. Postural sway increased during co-speech versus no-speech gestures, right versus left hand, and egocentric versus allocentric gestures. Co-speech elicited increased left premotor and supplementary motor cortex (PMC) activation. Egocentric ges- tures produced greater frontal cortex and Broca's area activation than allocentric gestures. Co-speech gestures increase postural instability and recruit shared motor-cognitive resources within the left premotor cortex, sug- gesting that speech, gesture production, and balance control compete for overlapping neural networks. Right- hand and egocentric gestures produced the strongest interference effects, indicating that gesture characteristics modulate motor-cognitive demands during postural control.
Keywords
Postural control, Co-speech gestures, Neuroimaging, Dual-task interference, Motor-cognition
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Rights
© The Author(s) 2026 Licensed to Smith College and distributed CC-BY 4.0 under the Smith College Faculty Open Access Policy.
Version
Author's Accepted Manuscript
Recommended Citation
Lifton Lewis, Sasha; Lu, Weina; and Helmich, Ingo, "Co-speech Gestures Destabilize Posture via Shared Motor-Cognitive Resources" (2026). Exercise and Sport Studies: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/ess_facpubs/65