Social interaction or communication requires the sharing of attention. If two people are not paying attention to one another then there is no interaction and no communication. Shared attention is essential for a child’s development of social cognition and communication skills. Two types of shared attention have been identified: mutual gaze when two people face one another and attend to each others eyes; and joint attention when two people look at a third person or object. Joint attention is not the same for both individuals because one initiates it and the other responds.
In a recent paper, researchers studied shared attention (Takahiko Koike etal; Neural substrates of shared attention as social memory: A hyperscanning functional magnetic resonance imaging study ; NeuroImage 125 (2016) 401–412). This cannot be done on an individual level as it involves social exchange and so the researchers used fMRI hyperscanning. Real time video recording and projection allowed two individuals in separate scanners to communicate through facial expression and eye movements while they were both being scanned. Previous studies had shown neural synchronization during shared attention and synchronization of eye blinks. They found that it was the task of establishing joint attention which requires sharing an attentional temporal window that task creates the blink synchrony. This synchrony is remembered in a pair specific way in social memory.
Mutual gaze is needed to give mutual attention - and that is needed to initiate joint attention which requires a certain synchrony - and finally that synchronizing results in a specific memory of the pair’s joint attention which allows further synchrony during subsequent mutual gaze without joint attention first.
Here is their abstract: “During a dyadic social interaction, two individuals can share visual attention through gaze, directed to each other (mutual gaze) or to a third person or an object (joint attention). Shared attention is fundamental to dyadic face- to-face interaction, but how attention is shared, retained, and neutrally represented in a pair-specific manner has not been well studied. Here, we conducted a two-day hyperscanning functional magnetic resonance imaging study in which pairs of participants performed a real-time mutual gaze task followed by a joint attention task on the first day, and mutual gaze tasks several days later. The joint attention task enhanced eye-blink synchronization, which is believed to be a behavioral index of shared attention. When the same participant pairs underwent mutual gaze without joint attention on the second day, enhanced eye-blink synchronization persisted, and this was positively correlated with inter-individual neural synchronization within the right inferior frontal gyrus. Neural synchronization was also positively correlated with enhanced eye-blink synchronization during the previous joint attention task session. Consistent with the Hebbian association hypothesis, the right inferior frontal gyrus had been activated both by initiating and responding to joint attention. These results indicate that shared attention is represented and retained by pair-specific neural synchronization that cannot be reduced to the individual level.”
The right inferior gyrus (rightIFG) region of the brain has been linked in other research with: interfacing between self and other; unconscious incorporation of facial expression in self and others; the release from mutual attention; and, neural synchronization during social encounters. The rightIFG is active in both initiating and responding to joint attention and in the synchrony during mutual gaze (when it is present). However it is unlikely to cause blinking directly. “Neural synchronization of the right IFG represents learned shared attention. Considering that shared attention is to be understood as a complementary action due to its social salience, relevance in initiating communication, and joint action, the present finding is consistent with a previous study by Newman-Norlund et al. who showed that the right IFG is more active during complimentary as compared to imitative actions.” Communication, communication, communication!
This fits with the theory that words steer joint attention to things present or absent, concrete or abstract in a way that is similar to the eyes steering joint attention on concrete and present things. Language has harnessed the brain’s mechanisms for joint attention if this theory is correct (I think it is).