Search engines are now augmenting search results with social annotations, i.e.,
endorsements from users’ social network contacts. However, there is currently a
dearth of published research on the effects of these annotations on user choice.
This work investigates two research questions associated with annotations: 1) do
some contacts affect user choice more than others, and 2) are annotations relevant
across various information needs. We conduct a controlled experiment with 355
participants, using hypothetical searches and annotations, and elicit users’
choices. We find that domain contacts are preferred to close contacts, and this
preference persists across a variety of information needs. Further, these contacts
need not be experts and might be identified easily from conversation data.