Strengthening the case for stimulus-specificity in artificial grammar learning: no evidence for abstract representations with extended exposure.

Different theories have been proposed regarding the nature of the mental representations formed as a result of implicit learning of sequential regularities. Some theories postulate abstract surface-independent representations, while other theories postulate stimulus-specific representations. This article reports three experiments investigating the development of abstract representations in artificial grammar learning (AGL), using a methodological approach developed by Conway and Christiansen (2006). In all the experiments, the number of blocks during the exposure phase was manipulated (6 blocks vs. 18 blocks of exposure to sequences). Experiments 1 and 2 investigated both visual and auditory learning where sequences were presented element-by-element. Experiment 3 investigated visual learning using a sequence-by-sequence presentation technique more commonly used in visual AGL studies. Extending previous research (Conway & Christiansen, 2006) and in support of stimulus-specific accounts, the results of the experiments showed that extended observational learning results in increased stimulus-specific knowledge rather than abstraction towards surface-independent representations.