14. The computer program product of claim 13 , wherein determining a topic of the first content based on the lexical features of the first content comprises: comparing the lexical features of the first content to stored lexical features, wherein the stored lexical features are associated with one or more topics; and determining the topic of the first content based on the comparison.
13. A computer program product comprising a non-transitory computer-readable medium containing computer program code for performing the method comprising: receiving information about an action performed by a user, wherein the action comprises at least one of creating or interacting with first content, the user associated with an interest graph and representative of interests of the user in a plurality of topics; analyzing language of the first content to identify lexical features of the first content; determining a topic of the first content based on the lexical features of the first content; and updating the interest graph to modify an attachment level in the interest graph representing an interest of the user in the topic of the first content.