Cognitive control of sequential knowledge in 2-year-olds: evidence from an incidental sequence-learning and generation-task

Thirty-eight two-year-olds were trained under incidental instructions on a six element deterministic sequence of spatial locations. Following training, participants were informed of the presence of a sequence and asked to either reproduce or suppress the learned material. Children's production of the trained sequence was modulated by these instructions. When asked to suppress the trained sequence they were able to increase generation of paths that were not from the training sequence. Their performance was thus dependent on active suppresion of knowledge rather than a random generation strategy. This degree of control in two-year-olds stands in stark contrast to 3-year-olds' failure to control explicitly instructed rule-based knowledge (as measured the Dimensional Change Card Sort Task). We suggest that this is because the incidental nature of the learning enables the acquisition of a more procedural form of knowledge with which this age-group have more experience prior to the onset of fluent language.