A system for and method of automatically selecting among a plurality of alternative modes of an activity. A user behaviour knowledge base (30) is provided for holding a number of user profiles, one for each registered user. The user behaviour knowledge base comprises a plurality of given fact evidential logic rules with associated fuzzy sets and weights personalised to each user to form the user profiles. The user behaviour knowledge base is operable to select for any user one among the plurality of alternative modes of activity by applying the given fact evidential logic rules held in that user's user profile. The user behaviour knowledge base is continually refined using a common sense knowledge base (40) comprising a plurality of common sense evidential logic rules with associated fuzzy sets and weights. The common sense evidential logic rules respond to activity data and the user identifier to output common sense support values which, in use, are continually applied to modify the user profile of the currently active user by adjusting the fuzzy sets and/or the weights held in that user's profile for the given fact evidential logic rules. The user profiles are thus personalised by monitoring of each user's activity. <IMAGE>
Artificial intelligence user profiling