Working memory training improves children’s syntactic ability but not vice versa: A randomized control trial

•A Randomised Control Trial with 104 children found the first cognitive transfer effects from working memory to syntax but not vice versa.•In the case of children’s first language, working memory training was as effective as language training in boosting syntactic performance.•It is proposed that transfer is mediated by cognitive mechanisms common to both working memory and syntax.•These data represent some of the strongest evidence to date that domain-general cognition is deeply integrated into developmental language processes.