Van Bommel, M., Van Prooijen, J.-W., Elffers, H., & Van Lange, P. A. M. (2014). Intervene to be seen: The power of a camera in moderating the bystander effect. Social Psychological and Personality Science, 5, 459-466.

Abstract: 

Security cameras became such part of everyday life, that their presence may escape from our conscious attention. The present research examines the impact of cameras on intervening in crime, a situation in which the classic bystander effect has been uncovered. In our experimental set-up, participants witnessed how another participant (a confederate) stole money, either in the presence of two, or no other bystanders. Moreover, we used a security camera to make people feel watched. We expected to replicate the bystander effect without security camera presence, and an attenuation of the bystander effect with a security camera present. As expected, findings revealed that without a camera, participants were less likely to stop our confederate from stealing money when other bystanders were present. However, when there was a camera present this effect was attenuated: The camera increased intervention when people are otherwise least likely to help — when other bystanders are present.