Automatic comparisons of artificial digits never compared: Learning linearordering relations

In 2 experiments, participants were trained to perform magnitude decisions, that is, decide which of 2 arbitrary symbols in a pair represented a large r magnitude. The symbols corresponded to locations on an implicit linear sc ale. Training resulted in a Stroop-Like size congruity effect when the part icipants had to decide which symbol in a pair was physically larger. This e ffect, showing automaticity of the processing of magnitude relations, was a lso obtained for pairs never encountered during practice. The implications of these findings for processing of magnitude relations and for theories of automaticity are discussed.