Getting users to use a new feature by showing others who used the feature isn’t a new concept for interfaces. It’s even more powerful when the other users are friends… because it gives an air of legitimacy to the feature. The technique is probably as old as public markets.
If your friend buys somewhere and tells you about it, well hey, why shouldn’t you do it too? They’ve just taken a lot of the upfront work out of the process for you. LinkedIn does an especially slick job of this with a feature that scans your email contacts and suggests connections.
The feature is contentious. Let’s be honest- I may learn about a few connections, but what I’m really doing is giving LinkedIn new leads for users (or more information they can use).
On the right, they show pictures of a bunch of my connections who have presumably already done this. But are any of my connections aware they’re “endorsing” the feature? Sure, LinkedIn’s byline only says that these faces used the feature, not that they liked it. But I see that as just covering their asses to avoid a Facebook Beacon-like incident. If I started a restaurant and posted headshots of celebrities who ate there, there’s a lot more implicitly being said than “Brad Pitt was here.”
On the other hand, it’s notoriously hard to get users to do pretty much anything other than look at porn online. Let’s say LinkedIn wanted to be super upstanding and had a Did you like it? question box on their site after using this tool. How many people would actually answer it? Probably few, if any. Not enough to fill out the 7 photos they need for the layout. What if they only show users who used this tool and connected with someone as a result? That seems like a pretty good indicator that a user would be okay with psuedo-endorsing the tool to others.
Co-opting a user’s endorsement is a tricky ethical question. At the end of the day, you can’t stop and ask your users for constant feedback and endorsements. But does that give you license to present interfaces these interfaces anyways?