Character  &  Context

Trusting Groups: Size Matters

Feature Image

By Stephen La Macchia

How do you decide whether to approach a group of strangers for help, whether to sign a contract with one company or another, or whether to be fully honest about your abilities and interests when answering questions from a job interview panel?

There are a range of everyday interactions in which an individual must make decisions about how much to trust a group of people. These decisions are sometimes based on limited information and made with little or no previous contact with the group. So how do we decide whether the group is trustworthy?

Despite a vast research literature on the psychology of trust, relatively little is known about how people generally assess the trustworthiness of groups. To date, research has mostly focused on how people judge the trustworthiness of individuals.

In fact, the nonverbal cues of individuals’ trustworthiness are so well established that researchers can easily generate an image of a trustworthy face, and have been able to successfully program a robot to look and act trustworthy [i]! When it comes to the subtle cues or attributes that make a group look trustworthy, however, the picture is a lot less clear.

In a recent research article published in Personality and Social Psychology Bulletin [ii], my co-authors and I shed some light on how people judge groups’ trustworthiness, examining how this is influenced by one basic attribute of groups: their numerical size.

Every type of group can vary in size; there are small and large families, work teams, audiences, organizations, towns, countries. The basic or relative size of any particular group is one of the most readily perceived and easily defined attributes, so it makes sense that a group’s size would be one of the cues people use to judge its trustworthiness. A number of psychological theories indirectly suggest this possibility, but previous research has not directly and thoroughly tested it.

In our article, we present seven studies showing that all else being equal, people trust smaller groups more than larger groups.

Most of these studies were experiments in which we manipulated whether a hypothetical group was relatively small or large given the context, and had participants answer questions regarding their trust, expectations, and approach intentions towards the group. We found a subtle but consistent smaller-group trust preference across a range of contexts. This preference emerged in both abstract judgments and specific interaction scenarios involving large-scale groups (e.g., organizations and towns) and small-scale groups (e.g., decision panels), and both positive and negative potential outcomes.

For example, one study had participants contemplate a trust-sensitive financial decision involving a group (e.g., signing a contract with a company, waiting for people in a town to hand in your lost wallet). Participants trusted the group significantly more if they were told it was relatively small (e.g., one third the size of similar companies or neighboring towns) than if they were told it was relatively large (e.g., three times the size of others), and this positively influenced their willingness to take the corresponding risk towards the group.

In two other studies, participants imagined facing a disciplinary panel (e.g., for having committed academic plagiarism). Participants indicated significantly more trust of the panel and expected significantly less severe punishment when the panel consisted of three people compared to when it consisted of ten people.

So why is it that people take smaller group size as a cue to group trustworthiness?

Well, in two of our studies we measured perceptions of the groups’ warmth and competence (two basic dimensions of group perceptions and stereotypes). In these studies, we found that warmth perceptions (but not competence perceptions) positively mediated the smaller-group trust preference.

In another study, we asked people why they trusted smaller groups more than larger groups (once they had already indicated that they did), and they indicated that small groups are more close-knit, accountable, easy to influence, and evocative of intimacy groups (i.e., family or friends).

Altogether, these results point to the apparent “small = trustworthy” heuristic arising from small group size reminding people of their own intimacy groups and thus evoking perceptions of communal traits such as warmth and accountability. More pragmatically, the tentative finding that people see small groups as easier to influence than large groups—consistent with social impact theory—may partly explain the expectation of more favorable outcomes from a smaller group in a trust interaction.

Further research is needed to replicate this smaller-group trust preference and establish its boundary conditions, as well to investigate possible applied implications. For example, can companies increase their brand trust by making themselves look smaller than their competitors? Can politicians make themselves appear more trustworthy by emphasizing the small towns or organizations they have belonged to? These remain open questions, but our research shows that when it comes to group size and trustworthiness, smaller is generally better.

Stephen La Macchia recently completed his PhD in social psychology at The University of Queensland in Brisbane, Australia. His research interests include trust, group perception, social norms, collective action, and political attitudes and behaviour.


[i] DeSteno, D., Breazeal, C., Frank, R. H., Pizarro, D., Baumann, J., Dickens, L., & Lee, J. J. (2012). Detecting the trustworthiness of novel partners in economic exchange. Psychological Science, 23(12), 1549-1556. doi:10.1177/0956797612448793

[ii] La Macchia, S. T., Louis, W. R., Hornsey, M. J., & Leonardelli, G. J. (2016). In small we trust: Lay theories about small and large groups. Personality and Social Psychology Bulletin. Advance online publication, July 1, 2016. doi:10.1177/0146167216657360

Blog Category: 

About our Blog

Character & Context is the blog of the Society for Personality and Social Psychology (SPSP). With more than 7,500 members, SPSP is the largest organization of social psychologists and personality psychologists in the world.   

Learn More ›

Questions ›

Contribute to the Blog ›

Get Email Updates from the Blog