Systems and methods for the forming of user device groups are presented. First, logical relationship information can be recorded, the logical relationship information describing logical relationships between a first user and other users, the logical relationship information associated with a social networking service. Communications between the first user and the other users, the communications being of at least two different types of communications, may be monitored. A first user group in which to add the first user is determined based on the logical relationship information, a first factor and a second factor, the first factor corresponding to a first of the different types of communications and the second factor corresponding to a second of the different types of communications, the determining including applying a first time-varying function to the first factor and a second time-varying function to the second factor to represent an effect of passage of time, the first time-varying function being different than the second time-varying function.