Speaking Without Words

Hello family and friends,

As my time in Paris comes to a close, I look back on everything I have learned during these speedy four weeks. From analyzing primary articles to visiting the libraries of famous French neurologists, it has truly been an enlightening experience. Nevertheless, one of the hardest aspects of studying abroad has been the language barrier. Knowing only a handful of French phrases, I have had to use alternative methods of communication in a variety of social contexts. After spending ample time interacting with Parisians, I find myself growing less anxious in my daily exchanges with non-English speakers. Instead, I take comfort in the fact that nonverbal communication can be as effective, if not more effective, than verbal communication. Interested in the broad category of nonverbal communication, I took it upon myself to do a little more research. As it turns out, what I found relates to the grand field of neuroscience.

First off, let me start by asking what you think of when you hear the phrase “nonverbal communication”. Personally, I imagine someone using a simple combination of facial expressions and bodily gestures to convey meaning. However, after reading a new study on the phenomenon, I realize that the cognitive processes involved in nonverbal exchanges are quite complex. Let me explain.

In a study led by Alexandra Georgescu from the University Hospital of Cologne in Germany, researchers delved into two types of perceived human motion, movement fluency and movement contingency, and their relationship to nonverbal interactions (Georgescu et al., 2014). For reference, movement fluency is the quality of one’s motions. Movement contingency is coordinated patterns of movement between two people. Thus, fluency deals more with the individual while contingency depends on the interactive dynamic between two people. What is the importance of these terms? Well, through their experimental design, Georgescu et al. found that manipulating movement fluency and contingency changes our perception of the “naturalness” of a nonverbal social interaction. Looking into the neural correlates involved with this perception, Georgescu et al. hoped to learn more about the processes occurring in the brain during nonverbal social interactions.

Figure 1. The four experimental video conditions.

In order to study movement fluency and contingency in the context of nonverbal social interactions, researchers measured the brain activity of study participants as they watched virtual dyadic interactions, or interactions between a pair. By virtual, I mean experimenters presented a silent video showing two mannequins interacting with one another (Figure 1). The goal here was to evaluate the brain’s response to natural and unnatural movements committed by the mannequins during their interactions. By doing this, researchers hoped to determine the neural networks involved in perceiving motion during nonverbal exchanges. Two kinds of motional manipulations were used during presentation of videos. The first targeted motion fluency by altering the smoothness of each mannequin’s movements. Here, alterations resulted in mannequins making rigid, robot-like movements. The second targeted motion contingency by eliminating one of the mannequins and having a mirror image of the remaining mannequin take its place. Here, Georgescu et al. reasoned that mirrored movements of the one mannequin would be interactively meaningless and thus non-contingent. Four 10-second videos were used, each presenting a different combination of manipulated and non-manipulated movements (refer back to Figure 1). Participants watched the videos while their brain activity was monitored by a functional magnetic resonance imaging (fMRI) machine. After presentation of each video, participants were instructed to quickly rate the “naturalness” of the clip on a scale from 1 to 4, 1 being “very unnatural” and 4 being “very natural”. Georgescu et al. ran many trials with 28 participants to gather sufficient data.

So… what were the results?

Figure 2. AON activation in response to visualizing contingent movement patterns.

Georgescu et al. found that participants were sensitive to changes in both movement contingency and fluency, and that participants considered the interactions to be most “natural” when movement was both contingent and fluid. From the imaging results, researchers concluded that visualizing movement contingency engages a network known as the “action observation network”, or AON (Figure 2). The AON includes several brain regions including bilateral posterior superior temporal sulcus (pSTS), the inferior parietal lobe (IPL), the inferior frontal gyrus (IFG), the adjacent ventral as well as dorsal premotor cortices (PMv, PMd), and the supplementary motor area (Wow, those are pretty overwhelming names!). In contrast, visualizing rigid movements (manipulated movement fluency) activated a different network known as the “social neural network”, or SNN (Figure 3). The SNN comprises of the medial prefrontal cortex (mPFC), the posterior cingulate cortex (PCC), the temporoparietal junction (TPJ), and the adjacent pSTS (I promise there are no more scary words). Thus, these results suggest that the AON may be a key neural network in the understanding of social interactions. Meanwhile, the SNN might play a role in interpreting incongruences during social interactions. Relating back to my daily experiences here in Paris, it would seem that my AON is activated as I coordinate my movements with a French speaker in a nonverbal exchange. If he or she makes a movement I fail to interpret, my SNN most likely activates as I try to sort out the ambiguity. Voila! Science.

Figure 3. SNN activation in response to visualizing rigid movement fluency.

Although I had difficulty interpreting the study’s imaging data due to poorly labeled figures, I found this article to be extremely interesting. It considered the processes of nonverbal communication in a novel fashion while providing solid evidence for the differential roles of the AON and SNN in nonverbal social exchanges. It would be exciting to perform similar experiments using videos displaying specific social contexts. That way, we might learn if social context leads to differential brain activity.

 

Always a pleasure,

Christian

 

References

Georgescu AL, Kuzmanovic B, Santos NS, Tepest R, Bente G, Tittgemeyer M, Vogeley K (2014) Perceiving nonverbal behavior: neural correlates of processing movement fluency and contingency in dyadic interactions. Hum Brain Mapp.35(4):1362-78

Figures 1-3 are from Georgescu et al., 2014.

“Welcome” image was obtained using a Creative Commons search:

Pixabay

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