Brain-to-Brain Coupling: A Mechanism for Creating and Sharing a Social World

"Thus, just as the Copernican revolution simplified rather than complicated understanding of the physical world, embracing brain-to-brain coupling as a reference system may simplify understanding of behavior by revealing new forces that operate among individuals and shape one’s social world."

This opinion article from Trends in Cognitive Sciences February 2012, Vol. 16, No. 2 focuses on the processing when one brain couples in an interaction with another: "We argue that in many cases the neural processes in one brain are coupled to the neural processes in another brain via the transmission of a signal through the environment. Brain-to-brain coupling constrains and shapes the actions of each individual in a social network, leading to complex joint behaviors that could not have emerged in isolation."

The comparison between the analogous coupling of brains through wireless communication is made, but differences are described as the coordination of behaviour between the sender and receiver: "seeing or hearing the actions, sensations or emotions of an agent trigger cortical representations in the perceiver (so-called vicarious activations....)" From examples of language acquisition for communication, "these data from songbirds, human adults and infants show that the development of communication is fundamentally embedded in social interactions across individual brains."

Diagrams of speech generation and reception in the brain are used to illustrate the following: "According to the brain-to-brain coupling framework, vocal communication emerges through the interactions or entrainment between the brains and bodies of signaler and receiver....Once brains are coupled to each other via speech signals, information can be shared and exchanged more efficiently. Human communication protocols can be divided into two types: monologues, in which only one speaker sends information and listeners receive it, and dialogues, in which interlocutors have to interweave their activities with precise timing." In dialogues, speakers align their representations by imitating each other’s choices of speech sounds, grammatical forms, words, and meanings because: 

1. "within an individual’s brain, production (speaking) and comprehension (listening) are coupled to each other and rely on shared linguistic representations...
2. ...when a speaker produces a particular representation, it primes (activates) both the comprehension and the corresponding production of the same representation in listeners, making them more likely to use it in their speech."

Research evidence of brain imaging shows that "the speaker's and listener's brains exhibited joint, temporally coupled, response patterns....Thus, whereas stimulus-to-brain coupling... is mostly locked to momentary states of affairs in the environment, brain-to-brain coupling... can provide a mechanism for transmitting information regarding temporally and spatially remote events."

Hand gestures and facial expressions can also stimulate brain-to-brain coupling. "Many human actions, such as playing basketball or operating a sailboat, require tight spatiotemporal coordination across team members.... An increasing body of evidence shows that, during joint actions, people become implicitly coupled at motor, perceptual and cognitive levels...The choices an individual makes are often influenced and modified by the decisions of others. Individuals playing a strategy game keep track not only of the actions of the opponent but also of how opponents are influenced in response to their own actions."

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