How do lay people come to trust the Automatic External Defibrillator?

Defibrillators are now widely installed in a variety of public places for the immediate treatment of people who have collapsed with a suspected cardiac arrest. These initiatives are predicated on the defibrillator being used by 'lay' volunteers. This presents a problem of trust, as the volunteer rescuers need to trust an unfamiliar technology to diagnose and treat an immediately life-threatening condition they are unlikely to have encountered before. Based on qualitative interviews with volunteers and defibrillator trainers, we show how trust in the defibrillator is constructed and maintained as a social process. This trust is a complex phenomenon, placed in technology, people and institutions, all of which work together to enable the volunteer, when an emergency occurs, to 'push the button.'