The development of implicit learning from infancy to adulthood: item frequencies, relations, and cognitive flexibility.

The majority of cognitive processes show measurable change over the lifespan. However, some argue that implicit learning from environmental structure is development invariant [e.g., Muelemans et al. [1998] Experimental Child Psychology, 69, 199-221; Reber [1993] Implicit learning and tacit knowledge: An essay on the cognitive unconscious. Oxford University Press], while others have shown that adults learn faster than children [Thomas et al. [2004] Journal of Cognitive Neuroscience, 16, 1339-1351]. In two experiments, we tested infants through adults using the same saccade latency measure and behavioral learning paradigm. We examined implicit learning when subjects are presented with interleaved regularities acting on one item, as well as the ability to adjust behavior when learned information is violated. In one comparison, the first- (item frequencies) and second- (spatiotemporal item relations) order statistics are in conflict, allowing us to examine flexibility in learning from multiple parameters. Data from Experiment 1 (N = 90, 6- to 30-year olds) showed no developmental differences in either implicit learning from environmental regularity or flexibility of learning from conflicting parameters across our age range. Accuracy data showed that children are especially sensitive to low frequency relative to high frequency items. In Experiment 2, we showed that 7- to 11-month-old infants had a saccade latency profile that was consistent with task structure, that is, they simultaneously learned both item frequencies and spatiotemporal relations, as indicated by data patterns similar to those obtained in Experiment 1. Taken together, these data provide support for developmental invariance in implicit learning from environmental regularities.