We want to follow the lead and advice of a legitimate authority.
(for example, take a look at the Milgram Experiment)
We all look for guidance and direction to some extend. Especially when something is new and users feel a little uncertain about what to do or what to choose. An authority figure or brand can guide them through you webshop to reassure them and give them direction on what the right choices are. Consider letting famous/ well known people from within your community or from TV to promote your products or your brand.
Repeat Cashmere has a Magento based e-commerce webshop and does a perfect job on 'exploiting' this theory. They have top model Doutzen Kroes promoting their product on their webshop. Well done!