Statistical learning is lasting and consistent over time.

Implicit detection of statistical regularities is thought to be a ubiquitous facet of cognition; yet, we know little about statistical learning (SL) over time. A recent study showed that visual SL can be observed at 24 h post stimulus (Kim et al., 2009 [14]). Here we sought to obtain a finer-grained picture of visual SL over time. We employed an embedded triplet paradigm and delayed presentation of the surprise test phase, in relation to the initial familiarisation phase, across five time periods: 30 min, 1 h, 2 h, 4 h and 24 h. Results revealed a significant degree of SL at each delay period. Moreover, the degree of SL was consistent across the five delay periods. These results suggest that visual SL is remarkably consistent over time. It does not appear to be fragile and does not appear to be enhanced by sleep in healthy adults. This robustness is desirable in a mechanism thought to underpin a broad range of mental activities including language processing. Future research might use the methodology we report here to examine whether similarly stable levels of SL can be observed in individuals with language impairment, such as those with SLI and dyslexia, compared with typical peers.