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Unintentional Interpersonal Synchronization Represented as a Reciprocal Visuo-Postural Feedback System: A Multivariate Autoregressive Modeling Approach.

Okazaki S, Hirotani M, Koike T, Bosch-Bayard J, Takahashi HK, Hashiguchi M, Sadato N - PLoS ONE (2015)

Bottom Line: As for the causality analysis, noise contribution ratio (NCR), the measure of influence using a multivariate autoregressive model, was also computed to identify the degree to which one's postural sway is explained by that of the other's and how visual information (sighted vs. blindfolded) interacts with paired participants' postural sway.It was found that for synchronization to take place, it is crucial that paired participants be sighted and exert equal influence on one another by simultaneously exchanging visual information.Furthermore, a simulation for the proposed system with a wider range of visual input showed a pattern of results similar to the behavioral results.

View Article: PubMed Central - PubMed

Affiliation: Division of Cerebral Integration, National Institute for Physiological Sciences, Okazaki, Aichi, Japan.

ABSTRACT
People's behaviors synchronize. It is difficult, however, to determine whether synchronized behaviors occur in a mutual direction--two individuals influencing one another--or in one direction--one individual leading the other, and what the underlying mechanism for synchronization is. To answer these questions, we hypothesized a non-leader-follower postural sway synchronization, caused by a reciprocal visuo-postural feedback system operating on pairs of individuals, and tested that hypothesis both experimentally and via simulation. In the behavioral experiment, 22 participant pairs stood face to face either 20 or 70 cm away from each other wearing glasses with or without vision blocking lenses. The existence and direction of visual information exchanged between pairs of participants were systematically manipulated. The time series data for the postural sway of these pairs were recorded and analyzed with cross correlation and causality. Results of cross correlation showed that postural sway of paired participants was synchronized, with a shorter time lag when participant pairs could see one another's head motion than when one of the participants was blindfolded. In addition, there was less of a time lag in the observed synchronization when the distance between participant pairs was smaller. As for the causality analysis, noise contribution ratio (NCR), the measure of influence using a multivariate autoregressive model, was also computed to identify the degree to which one's postural sway is explained by that of the other's and how visual information (sighted vs. blindfolded) interacts with paired participants' postural sway. It was found that for synchronization to take place, it is crucial that paired participants be sighted and exert equal influence on one another by simultaneously exchanging visual information. Furthermore, a simulation for the proposed system with a wider range of visual input showed a pattern of results similar to the behavioral results.

No MeSH data available.


Related in: MedlinePlus

Simulated results for time lag in synchronization.The figure illustrates the relationship between the synchronization time lag for the simulated and the behavioral data (for the simulation procedures, see Fig 2). The colored dots, green, red, and blue, in the figure correspond to the results for the Open-Open, Blindfold-Open, and Open-Blindfold conditions, respectively. The same color was used for the regression line for each of the conditions. The slope for each regression line was significantly higher than 0, suggesting a positive relation between the simulated and behavioral data.
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pone.0137126.g006: Simulated results for time lag in synchronization.The figure illustrates the relationship between the synchronization time lag for the simulated and the behavioral data (for the simulation procedures, see Fig 2). The colored dots, green, red, and blue, in the figure correspond to the results for the Open-Open, Blindfold-Open, and Open-Blindfold conditions, respectively. The same color was used for the regression line for each of the conditions. The slope for each regression line was significantly higher than 0, suggesting a positive relation between the simulated and behavioral data.

Mentions: The experimental results of the time lag in postural sway along the AP axis for the Near DISTANCE condition were replicated in our simulation. The time lag of postural sway synchronization in the simulated data was correlated with that in the behavioral data across pairs of participants in the OO, BO, and OB conditions (OO: B1 = 1.23, t = 6.866, p < 0.001; B0 = -6.37, t = 0.206, p = 0.839 (uncorrected); BO: B1 = 1.20, t = 5.912, p < 0.001; B0 = 61.07, t = 0.723, p = 0.478; OB: B1 = 0.68, t = 4.700, p < 0.001; B0 = 178.26, t = 2.586, p = 0.018). In addition, the time lag in the OO condition was 68 ± 163 ms (mean ± SD). This result was not significantly different from 0 ms (p = 0.061). The time lag in both BO and OB conditions was significantly different from that in the OO condition (BO: -235 ± 353 ms, p < 0.001; OB: 397 ± 271 ms, p < 0.001) (see Fig 6). These simulated results are consistent with the results of the behavioral experiment reported above and reinforce our proposal about lag-0 synchronization of postural sway between two individuals.


Unintentional Interpersonal Synchronization Represented as a Reciprocal Visuo-Postural Feedback System: A Multivariate Autoregressive Modeling Approach.

Okazaki S, Hirotani M, Koike T, Bosch-Bayard J, Takahashi HK, Hashiguchi M, Sadato N - PLoS ONE (2015)

Simulated results for time lag in synchronization.The figure illustrates the relationship between the synchronization time lag for the simulated and the behavioral data (for the simulation procedures, see Fig 2). The colored dots, green, red, and blue, in the figure correspond to the results for the Open-Open, Blindfold-Open, and Open-Blindfold conditions, respectively. The same color was used for the regression line for each of the conditions. The slope for each regression line was significantly higher than 0, suggesting a positive relation between the simulated and behavioral data.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4580648&req=5

pone.0137126.g006: Simulated results for time lag in synchronization.The figure illustrates the relationship between the synchronization time lag for the simulated and the behavioral data (for the simulation procedures, see Fig 2). The colored dots, green, red, and blue, in the figure correspond to the results for the Open-Open, Blindfold-Open, and Open-Blindfold conditions, respectively. The same color was used for the regression line for each of the conditions. The slope for each regression line was significantly higher than 0, suggesting a positive relation between the simulated and behavioral data.
Mentions: The experimental results of the time lag in postural sway along the AP axis for the Near DISTANCE condition were replicated in our simulation. The time lag of postural sway synchronization in the simulated data was correlated with that in the behavioral data across pairs of participants in the OO, BO, and OB conditions (OO: B1 = 1.23, t = 6.866, p < 0.001; B0 = -6.37, t = 0.206, p = 0.839 (uncorrected); BO: B1 = 1.20, t = 5.912, p < 0.001; B0 = 61.07, t = 0.723, p = 0.478; OB: B1 = 0.68, t = 4.700, p < 0.001; B0 = 178.26, t = 2.586, p = 0.018). In addition, the time lag in the OO condition was 68 ± 163 ms (mean ± SD). This result was not significantly different from 0 ms (p = 0.061). The time lag in both BO and OB conditions was significantly different from that in the OO condition (BO: -235 ± 353 ms, p < 0.001; OB: 397 ± 271 ms, p < 0.001) (see Fig 6). These simulated results are consistent with the results of the behavioral experiment reported above and reinforce our proposal about lag-0 synchronization of postural sway between two individuals.

Bottom Line: As for the causality analysis, noise contribution ratio (NCR), the measure of influence using a multivariate autoregressive model, was also computed to identify the degree to which one's postural sway is explained by that of the other's and how visual information (sighted vs. blindfolded) interacts with paired participants' postural sway.It was found that for synchronization to take place, it is crucial that paired participants be sighted and exert equal influence on one another by simultaneously exchanging visual information.Furthermore, a simulation for the proposed system with a wider range of visual input showed a pattern of results similar to the behavioral results.

View Article: PubMed Central - PubMed

Affiliation: Division of Cerebral Integration, National Institute for Physiological Sciences, Okazaki, Aichi, Japan.

ABSTRACT
People's behaviors synchronize. It is difficult, however, to determine whether synchronized behaviors occur in a mutual direction--two individuals influencing one another--or in one direction--one individual leading the other, and what the underlying mechanism for synchronization is. To answer these questions, we hypothesized a non-leader-follower postural sway synchronization, caused by a reciprocal visuo-postural feedback system operating on pairs of individuals, and tested that hypothesis both experimentally and via simulation. In the behavioral experiment, 22 participant pairs stood face to face either 20 or 70 cm away from each other wearing glasses with or without vision blocking lenses. The existence and direction of visual information exchanged between pairs of participants were systematically manipulated. The time series data for the postural sway of these pairs were recorded and analyzed with cross correlation and causality. Results of cross correlation showed that postural sway of paired participants was synchronized, with a shorter time lag when participant pairs could see one another's head motion than when one of the participants was blindfolded. In addition, there was less of a time lag in the observed synchronization when the distance between participant pairs was smaller. As for the causality analysis, noise contribution ratio (NCR), the measure of influence using a multivariate autoregressive model, was also computed to identify the degree to which one's postural sway is explained by that of the other's and how visual information (sighted vs. blindfolded) interacts with paired participants' postural sway. It was found that for synchronization to take place, it is crucial that paired participants be sighted and exert equal influence on one another by simultaneously exchanging visual information. Furthermore, a simulation for the proposed system with a wider range of visual input showed a pattern of results similar to the behavioral results.

No MeSH data available.


Related in: MedlinePlus