the age of exposure什么意思?

题目

the age of exposure什么意思?
原句：Perani et al.(1996) showed that late exposure results in separate localisations,but that proficiency may have a more significant role in the neural organisation in comparison with the age of exposure
这是关于双语习得者大脑结构的内容，上下文中还有early exposure和late exposure，我是真的没法从字面理解了~
另外相关的句子This classification takes into consideration the proficiency level,the age of exposure and,most importantly,the manner in which the two languages were acquired,i.e.in a natural setting simultaneously,or in classroom consecutively.

答案

在语言习得理论中,exposure 指“接触语言”,即给语言学习者提供语言素材 —— 教他们说话.
early exposure：早期接触（语言）
late exposure：后期接触（语言）
the age of exposure 接触（语言）的年龄