Social interaction and the subsequent generation of interpersonal relationships appear to be inherently linked to emotional well-being. Smartphones have increased an individual’s social footprint while remaining the primary way in which people communicate with each other via social media, phone calls and text messages. However, many researchers have questioned if the same technology is simultaneously preventing us from developing meaningful relationships?

At the same time, other research has started to focus on a variety of popular smartphone applications that have changed the way modern relationships are formed and maintained (e.g., Tinder, Snaphat). This work typically considers a participants’ own experience or data derived directly from applications themselves (Davidson, Joinson and Jones, 2018). However, it is also possible to explore real-wold social interaction via the variety of on-board sensors, which can also reveal group dynamics within the real-world (Piwek, Ellis and Andrews, 2016). For example, Bluetooth and location data derived from appropriate sensors can be used to infer when someone is meeting with others who are also running similar software of their device. This has also been referred to as Social fMRI whereby researchers can quantify social mechanisms in the real world (Aharony et al., 2011).

Smartphones can also generate data within other domains that psychology could take advantage of in the future including “smart cities.” For example, tracking and understanding individuals’ mobility using GPS location can allow for the forecasting of future movements. While smartphones have dramatically changed how large sections of society form and develop new relationships, this chapter points towards how the same technology can be leveraged further to understand how relationships and groups rapidly shift between offline and online contexts in the digital age.