L2 (English) spelling is positively correlated with L2 vocabulary size, but not with a measure that putatively taps visual statistical learning

Recent studies showed that a person’s visual statistical learning (VSL) ability is positively correlated with L1 and L2 literacy development. That is, people who are more adept at detecting implicit regularities in visual inputs tend to be or to become better readers. Most if not all studies that examined this link looked only into reading ability, oddly neglecting spelling, and importantly, they all relied on relatively small sample sizes. In light of these, we recruited a relatively large sample (64 advanced English learners) to investigate if performance on a commonly adopted VSL task (i.e., embedded triplet task) correlates with L2 (English) spelling proficiency, as indexed by a spelling test involving highly rare regular English words. We also administered a rote memorization task and an L2 vocabulary size test. In line with a growing body of literature, we found no evidence that performance on the VSL task correlated with L2 spelling. We did however find clear evidence that L2 learners with a larger L2 vocabulary size are also better spellers. We argue that while SL is linked to literacy development, traditional VSL measures may not be suitable for the investigation of individual differences owing to poor sensitivity. Our study, alongside Mak (2016), also demonstrates that false positives may arise due to small sample sizes. We, therefore, urge researchers worldwide, especially those interested in individual differences, to work towards reproducibility and better science by for example avoiding unjustifiably small sample sizes