Fig 1.
Schematic diagram of the relationship between intrapersonal and interpersonal synchronization, whether unimodal or multimodal.
A) and B) represent intrapersonal synchronization among the modalities of a single speaker. A) Full blue arrows highlight the unimodal relationship between the gestures generated by a single individual (i.e., head vs. head, head vs. wrist). B) Dashed blue arrows highlight the multimodal relationship between the voice and the gesture produced by a single individual (i.e., head vs. voice; wrist vs. voice). C) and D) represent the interpersonal synchronization between the modalities of speaker A and speaker B. C) Full red arrows highlight the unimodal relationships between the movements of speaker A and speaker B, and between their voices (i.e., head vs. head, head vs. wrist, voice vs. voice). D) Dashed red arrows highlight the multimodal relationships between the voice of speaker A and the gesture of speaker B and inversely (i.e., head vs. voice; wrist vs. voice).
Fig 2.
Wavelet transform of a vocal signal at 0.5 Hz.
The wavelet transforms represents one person’s voice saying “OK” every 2 seconds (0.5 Hz). The x-axis shows the time in seconds. The y-axis represents the different timescale expressed in frequency (Hz)(i.e., where the 1 Hz = 1/period = 1/1 sec). The main frequency of the voice is represented with the continuous yellow line at 0.5 Hz while the consecutive burst reflects the moment when frequency modification occurs (i.e., when the person said, “OK”).
Fig 3.
Intrapersonal degree and pattern of synchronization: Unimodal analyses.
(A) Differences in mean coherence between the experimental condition (red) and the virtual condition (blue), across different timescales. Mean and standard deviation are represented with dots and colored ribbons respectively. Grey areas depict significant differences between conditions. Here, all timescales are significant. (B) A circular histogram depicting the probability distribution for the experimental condition and ranges timescale where wavelet significantly differed from chance. The blue line represents the mean phase angle. Unimodal wrist vs. head relative phase angle oscillates around -6°, the head leading the wrist on average.
Fig 4.
Intrapersonal degree and pattern of synchronization: Multimodal analyses.
(A) differences in mean coherence between the experimental condition (red) and the virtual condition (blue), across different timescales. Mean and standard deviation are represented with dots and colored ribbons respectively. Grey areas depict significant differences between conditions. Here, all timescales are significant. (B) and (C) multimodal Head vs. Voice and Wrist vs. Voice relative phase angle respectively. The circular histograms depict the probability distribution for the experimental condition for timescales where wavelet significantly differed from chance. The blue line represents the mean phase angle. Head vs. voice relative phase angle oscillates around -18°, the voice leading the head on average. The wrist vs. voice relative phase angle oscillates around -34°, the voice leading the wrist on average.
Fig 5.
Interpersonal degree and pattern of synchronization: Unimodal analyses.
(A) differences in mean coherence between the experimental condition (red) and the virtual condition (blue), across different timescales. Mean and standard deviation are represented with dots and colored ribbons respectively. Grey areas depict significant differences between conditions. Here, the significative timescales are 0.125–0.375, and 1–30 for (A); 5–7 and 9–26 for (B). (C) A circular histogram depicting the probability distribution for the experimental condition and ranges timescale where wavelet significantly differed from chance. The blue line represents the mean phase angle. Unimodal wrist vs. head relative phase angle oscillates around 14°, the wrist leading the head on average.
Fig 6.
Interpersonal degree and pattern of synchronization: Multimodal analyses.
(A) differences in mean coherence between the experimental condition (red) and the virtual condition (blue), across different timescales. Mean and standard deviation are represented with dots and colored ribbons respectively. Grey areas depict significant differences between conditions. Here, the significative timescales are 2-30s. (B) and (C) multimodal head vs. voice and wrist vs. voice relative phase angle respectively. The circular histograms depict the probability distribution for the experimental condition for timescales where wavelet significantly differed from chance. The blue line represents the mean phase angle. Head vs. voice relative phase angle oscillates around 5°, the head leading the voice on average. The wrist vs. voice relative phase angle oscillates around 100°, the voice leading the wrist on average.
Table 1.
Overview of key findings in previous research on intrapersonal and interpersonal synchronization relative to our results.