Abstract: Apparatus for conducting Ordering Trials including a set of counters each incorporating an electrical circuit element which covertly identifies that counter and a box having locations for receipt of the counters. The counters and locations are fitted with plugs and sockets which are interengageable and permit the circuit element to be connected to electrical read-out circuitry which includes circuitry for identifying which counter is in which location. An arithmetic unit operating according to a predetermined algorithm is connected to the output of the interrogation circuitry to provide a measure of the result of a trial.