When learning languages, adults and children have different strengths. Adults excel at absorbing vocabulary, but children can easily pick up on subtle nuances of language that often elude adults.
A team of neuroscientists and psychologists led by Amy Finn, a postdoc at MIT’s McGovern Institute for Brain Research, has found evidence that in learning certain elements of language, adults’ more highly developed cognitive skills actually get in the way. They discovered that the harder adults tried to learn an artificial language, the worse they were at deciphering the language’s morphology—the structure and deployment of linguistic units such as root words and prefixes.
Linguists have long known that children readily absorb certain tricky elements of language, such as irregular past participles (like “gone” and “been” in English) or complicated verb tenses. Finn and her colleagues tested whether adults do themselves more harm than good by throwing all their at brainpower at these nuances. They had subjects listen to nine two-syllable nonsense words for about 10 minutes. Those in one group were told not to overanalyze what they heard; they were given the option of completing a puzzle or coloring to help them avoid overthinking while they listened. Those in the other group were told to try to identify the words they heard.
All subjects performed well on word segmentation and word ordering tasks. But in a task testing their ability to identify a language’s morphology, those who had paid closer attention to the original word stream performed much worse than those who had listened more passively.
It’s unclear whether adults can overcome this learning obstacle. But Finn is now testing the effects of “turning off” the adult prefrontal cortex using transcranial magnetic stimulation.