Hyperscanning with the Photon Cap: The Role of Neural Synchrony During Social Interaction

Introduction

In their study, Moffat et al. (2025) raised the question of increasing health risks caused by loneliness. Particularly, the study focused on the efficiency of intergenerational community programs bringing younger and older people together. It helps older adults stay physically, socially, and cognitively healthier, while also reducing younger adults’ negative stereotypes about aging. 

The study implies that because of these benefits, doctors are increasingly recommending participation in community programs, highlighting the acknowledgement of social connection as part of healthcare. However, the mechanisms behind the benefits were unclear, since most evidence of improvement comes from participants’ self-evaluation and earlier behavioral studies, not physiological data.

To shed light on the physiological side of relationship building and explain how these relationships produce positive effects, Moffat et al. (2025) conducted a longitudinal hyperscanning study using two Photon Cap devices provided through the Cortivision Pathfinder program.

Methods and Materials

Participants

Using a six-week art program, Moffat et al. (2025) followed 122 participants – 31 older adults (69+ years) and 91 younger adults (18-35 years) – from Zurich, Switzerland, recruited through universities, senior community groups, and social media.

Participants were paired into either intergenerational or same-generation teams based on their availability to attend the sessions. Gender matching was not prioritised due to scheduling differences. All pairs joined the study as strangers.

Procedure

The research team tracked changes in social wellbeing, how well the pairs worked together, and how closely their brain activity aligned during interactions using a hyperscanning approach, which allowed researchers to examine interpersonal neural synchrony (INS), or how closely people’s brain activity aligns during interaction.

Self-evaluation

At the start of each session, participants completed a short self-report questionnaire measuring overall, emotional, and social loneliness, and at the end of each session, participants rated how close they felt to their partner using a simple visual scale showing different levels of overlap between two circles. 

Participants reported their attitudes toward people of different age groups. They rated people their own age as well as people from another generation (older or younger). This allowed us to track changes in attitudes toward other generations over time.

Photon Cap use

Moffat et al. (2025) measured brain activity using two Photon Cap and Cortiview software which allowed participants to move and interact naturally similar to real-world social interactions. Each Photon Cap measured brain activity over key social brain areas (IFG and TPJ) using 16 light emitters and 10 light detectors, placed using standard 10-5 EEG placement based on brain mapping from the Neurosynth database. After placing the caps, a 3D scan of each participant’s head was created and then processed using MATLAB and the FieldTrip toolbox to ensure the sensors were positioned accurately over the regions of interest (ROI), allowing precise measurement of brain activity during interactions (Moffat et al., 2025).

Results

According to Moffat et al. (2025), the participants in intergenerational pairs reported feeling less lonely and more socially close than those in same-generation pairs. These benefits increased over repeated sessions for both groups.

Attitudes toward other generations remained stable overall. However, intergenerational pairs felt equally positive toward their own and the other generation, whereas same-generation pairs favored their own. 

Brain data revealed robust INS especially during collaborative drawing, with stronger and more widespread synchrony emerging over time. These effects were most pronounced in brain regions linked to social cognition and coordination and differed by task and pair type, highlighting distinct neural dynamics for intergenerational versus same-generation interactions.

INS data was meaningfully related to self-reported experience: greater synchrony was associated with lower loneliness, higher social closeness, and more positive intergenerational attitudes in specific contexts, suggesting that INS captures both the social and emotional quality of interaction and holds promise as a neural marker of changes in loneliness.

Based on preprint publication: Moffat, R., Dumas, G., & Cross, E. S. (2025). Longitudinal intergenerational hyperscanning reveals indices of relationship formation and loneliness (Preprint). bioRxiv. https://doi.org/10.1101/2025.10.14.682029