In this paper, we present a system that employs perceptual technologies (i.e. technologies that perceive the context through sensors such as cameras and microphone) to provide feedback about people's behaviour in small group meetings. The system measures aspects of behaviour that are relevant to the social dynamics of the meeting, speaking time and gaze behaviour, and provides visual feedback about these aspects to the meeting participants through a peripheral display. We describe the system properties and the perceptual components. Also, we present a study aimed at evaluating the effect of such a system on meeting behaviour. Groups of participants, amounting to 82 participants in all, discussed topics of general interest. Analysis of the data of 58 participants showed that feedback influenced the behaviour of the participants in such a way that it made over-participators speak less and under-participators speak more. Analysis of the micro-patterns of six participants indicated that feedback on gaze behaviour had little effect on the interaction dynamics. We conclude that perceptual technologies can be used to build services that may help people to improve their meeting skills and we consider some ways in which such systems may be deployed in meetings.