Parity effects in an implicit‐learning task

Is it possible to extract knowledge from complex material and then unknowingly use it? This key question in the field of implicit learning is addressed here in three experiments using the invariant paradigm. The experiments showed that after seeing a series of items consisting of pairs of 2‐digit numbers (e.g. [52; 74]) governed by a rule, subjects judged that new items that followed the rule were more familiar than ones that did not. Experiment 1 showed that this effect was observed when all bigrams seen in phase 2 were new. Experiments 2 and 3 controlled for some ‘classic’ biases and showed that the effect depended on what rule was at stake. An effect was observed only if the rule used brought to bear a salient categorical property in memory: parity.