This patent describes a method and apparatus to automatically and accurately winnow down arbitrarily large amounts of electronic information created by a particular population of actors to only those subsets of particular interest by having a causal relationship, even when retrieved documents containing this information do not individually satisfy the search criteria used. In an effective pixel region, pixels for obtaining image pickup signals used as a picked-up image are arranged. The controller, for example a speed controller, may have an input connected to an output of a pedal or desired speed setting mechanism.