Shiny happy people building trust?

Designing for trust in technology-mediated interaction is an increasing concern in CHI. In advertising, images of people have long been used to create positive attitudes to products or trust in brands. However, the evidence as to whether placing photographs of people on e-commerce web sites has the intended effect has been mixed. This paper reports a study that examined the effect of adding such photographs to 12 existing e-commerce sites, whose reputation had been established through customer ratings. In an experiment with 115 participants, trust was measured using methods that induced financial risk, adapted from experimental economics. Averaging across sites, neither the presence of a photo, nor trustworthiness of the person depicted, had a significant effect. However, the presence of photos reduced participants' ability to identify vendors with good and bad reputations -- the perceived trustworthiness of poorly performing vendors was increased, whereas that of vendors with good reputation was decreased. This result advocates caution when using photos on e-commerce sites to boost trustworthiness, and demonstrates the need for further research into interpersonal cues and on-line trust.