A system controller (20, 100, 30, 40) comprises a receiver (20) for receiving data about a system (10, 11) to be controlled and for associating the received data with a time factor; a summarizer (100) for updating a set of summary bins, each of which covers a respective period of time, and each of which stores a summary of the received data having, a time factor which falls within the respective period of time covered by the summary bin; a processor (30) for, processing the summary bins, for example in order to categorize an unknown entity (5) (such as a human user) interacting with the system under control (10, 11) (via a user interface (11) forming part of the system under control) such as into an adult interested in football, etc., and a director (40) for issuing control instructions to the system to be controlled based on the results of the processor (30). The periods of time covered by respective summary bins include overlapping periods of time and periods of time having different durations and are preferably overlapping, fuzzy, multi-scale bins.