The Power of Two

If you have some free time to socialize, do you prefer to spend it with your best friend or partner, or with a larger group of people?

A new study (Peperkoorn et al., 2020) now investigated what group size people actually look for and encounter in everyday life. The scientists asked more than 4,000 people from the U.S. and the Netherlands to report the size of their social groups for a wide variety of activities. For eight different activities (going to a bar, chatting at work, chatting off work, having dinner, going on a holiday, going to a movie theatre, working on a project, sports) people reported a group size of two more often than they reported larger group sizes. Interestingly, for about half of these activities, women reported a group size of two significantly more often than men did, suggesting that women prefer a social group size of two even more than men do.

In addition to these questionnaire data, the scientists also used a research technique called real-time experience-sampling. In this part of the study, 274 volunteers were asked seven times a day to report the last social situation they had experienced. The results were clear. Two was the most common group size with 52.6 percent, followed by three (18 percent), four (9.1 percent), five (4.3 percent), six (2.5 percent), seven (1.6 percent), eight (0.9 percent), nine (1.0 percent), ten (0.5 percent), eleven (0.6 percent), and “more than 11” (8.9 percent). Thus, this part of the study also suggested that two is the most common group size in social interactions.

So why do people prefer spending their time with one other person compared to spending their time with larger groups?

Peperkoorn and co-workers (2020) offer four different mechanisms to explain this finding:

1. Reciprocity: In general, social interactions with just one other person allow for more control of the situation, especially when it comes to reciprocity. When we interact with just one other person, one’s choices directly affect the other person and only that person. Thus, it is easy to distinguish whether there is mutual cooperation (for example, both people take turns paying for dinner) or whether someone acts selfishly (for example, one person never pays the bill). In larger groups, the situation gets much more complicated (for example, if person 1 stops paying the bill because person 2 never pays, it would also affect person 3 and person 4 and make a negative impression on them.
2. Coordination: It is much easier to coordinate social behavior with one person than with several other people at the same time, especially if we know the other person and their preferences well. This makes communication with just two people easier and more efficient.
3. Preventing social exclusion: In many social situations—such as a holiday in an unknown country, hanging out at a bar, or being in a new project group at work—it would be very unpleasant to be alone. Having another person around that comforts us in a sometimes daunting world is a great way to avoid feeling uncomfortable.
4. Reproduction: Social activities related to reproducing—such as finding a partner, spending time together as a couple, starting a family, and raising kids—are usually done by two people together.

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