In our daily life, we often synchronize our behavior with others: We unconsciously mimic others’ body postures or synchronize our clapping at the end of a concert. Recent research has shown that behavioral synchrony is related to inter-brain synchrony: When two people synchronously perform hand movements, this leads to inter-brain synchrony, that is an alignment in the brain oscillatory phases in both brains (Dumas, Nadel, Soussignan, Martinerie, & Garnero, 2010). Evidence strengthening the idea of an interplay between behavioral and inter-brain synchrony stems from recent research experimentally manipulating inter-brain synchrony (Novembre, Knoblich, Dunne, & Keller, 2017). Forced inter-brain synchrony established via transcranial alternating current stimulation facilitates behavioral synchrony. These studies assessed behavioral synchrony with regard to simple hand or finger movements. However, natural interactions are much more complex. One pivotal form of adjusting our behavior is during moments of Joint Attention. During Joint Attention we attend to the same object together with another person while we are both mutually aware of it. It requires monitoring the focus of attention of another person and appropriately aligning our own focus of attention and therefore reflects a highly complex behavioral synchronization. How can we investigate the interplay between inter-brain and behavioral synchrony during Joint Attention?

In my talk, I will present our dual EEG paradigm in which we measure brain activity simultaneously in two participants during Joint Attention moments. In addition, I will talk about our approach of using auditory entrainment as a non-invasive method to examine whether forced inter-brain synchrony in specific frequency bands can facilitate or hinder Joint Attention. 

Already 9-month-old infants show Joint Attention behavior. Crucially, attending to an object in a Joint Attention situations facilitates infants’ object encoding. However, the underlying neural mechanisms explaining an enhanced object encoding are not yet understood. Recent adult research has shown that an optimal alignment between an incoming stimulus and brain oscillatory phase supports information processing. In the second part of my talk, I will present our dual EEG paradigm to investigate whether inter-brain phase synchrony between caregiver and infant supports object encoding.