Less is more : depleting cognitive resources enhances language learning abilities in adults

It is still an unresolved question why adults do not learn languages as effortlessly as children do. We tested the hypothesis that the higher cognitive control abilities in adults interfere with implicit learning mechanisms relevant for language acquisition. Across 2 days, Dutch-speaking adults were asked to rapidly recite novel syllable strings in which, unannounced to the participants, the allowed position of a phoneme depended on another adjacent phoneme. Their cognitive control system was either depleted or not depleted prior to learning, after performing an individually tailored dual working-memory task under high or low cognitive load. A third group did not perform any cognitive task prior to training. Speech error analyses revealed stronger (and faster) learning of the novel phoneme combination constraints in the cognitively depleted group compared with the other two groups. This indicates that late-developing cognitive control abilities, and in particular attentional control, constitute an important antagonist of implicit learning behavior relevant for language acquisition. These findings offer novel insights into developmental changes in implicit learning mechanisms and how to alter them temporarily in order to improve language skills in adults.