Functional morphemes and mechanisms of early language processing

词汇范畴和功能范畴的区别是自然语言中最基本的区别。词汇类别包括名词、动词、形容词和副词。功能范畴包括限定词、助词、时态结尾等。词汇范畴也被称为实义词，因为它们承载着话语中意义的主要分量。相反，功能成分的主要作用是表示单词之间的语法关系。孩子们在一岁左右开始说话。他们会连续几个月说出一个单词，然后在18-20个月大的时候学会单词组合。两岁以下的语言包含实义词，通常缺少功能元素。这一特征可能表明幼儿不知道功能类别。然而，包括我的实验室在内的几个实验室利用感知测量进行的新研究表明，婴儿很早就开始处理功能性物品，远在他们能够生产这些物品之前。在我早期的研究中，我发现0-6个月大的婴儿能够区分虚词和实词。我后来证明，一岁前的婴儿能够感知和表示母语中特定的功能项目，并用它们来分割相邻的单词。一岁后不久，婴儿就能理解不同功能成分之间的语法关系，并能使用函词对实义词进行分类。这些发现表明，婴儿比以前认为的拥有更复杂的语法知识。在我的NSERC资助的下一个周期中，我将研究早期形态句法习得的两个问题：1)婴儿虚词习得的机制及其与实义词的语法关系；2)对限定功能词元（如英语-ing和法语-er的词尾）及其与词干的形态关系（如walk_walk-ing_walk-ed）的初步学习。对于1)，我们将测试假设，即弱词形和虚词（相对于实词）的高频率的组合特性使婴儿能够将它们视为功能元素，并使用它们来发现实词的语法特性（例如，使用限定词将相邻单词分类为名词，“a/the dog”，“a/the cat”）。为了精确地研究这些特性，我们将创建包含新单词的人工语言，并仔细操纵单词的形式和频率。使用这些材料的知觉实验将在一岁的孩子中进行。对于2)，将使用以熟悉的法语结尾-er和人工结尾的新单词来测试语言前和早期语言婴儿如何学习这些结尾以及相关单词的形态变化。在整个实验中，不同的训练条件与新词干和词尾将被用来检查输入因素。我们将检验基于分布的词形学习输出是否指导婴儿后续的词义学习。也就是说，婴儿首先学习到某些形式在形态上是相关的（例如，走路），这使他们能够期望这种变化的所有形式具有相同的核心意义。这一假设不同于标准观点，即儿童首先学习单个单词的含义，然后（在更晚的年龄）解释它们的内部形态结构。1)和2)都将测试比学习具体项目及其关系更多的东西。他们将测试婴儿在抽象层面概括结构的能力。这些研究将有助于更好地理解早期语言发展的机制，特别是抽象形态句法结构的初始习得。他们将为关于婴儿句法知识的性质和起源的更大的争论提供重要的数据。

The distinction between lexical and functional categories is the most fundamental one in natural languages. Lexical categories include nouns, verbs, adjectives and adverbs. Functional categories include determiners, auxiliaries, tense endings, etc. Lexical categories are also called content words, as they carry the main weight of meaning in utterances. In contrast, the primary role of functional elements is to indicate grammatical relations across words. Children start talking around age one. They produce one-word speech for months and then word combinations by 18-20 months of age. Speech below age two contains content words, typically missing functional elements. This characteristic may suggest that young children do not know functional categories. However, new research from several labs including mine using perceptual measures shows that babies start processing functional items early, long before they can produce them. In my early studies I found that 0-6-month-old babies distinguish function words versus content words. I later showed that infants before age one perceive and represent specific functional items in their native language, and use them to segment adjacent words. Shortly after age one, infants understand the grammatical relations across different functional elements and use functors to categorize content words. These findings reveal that infants have more sophisticated grammatical knowledge than previously assumed. In the next cycle of my NSERC grant, I will address 2 issues in early morpho-syntactic acquisition: 1) the mechanisms underlying infants’ acquisition of function words and their grammatical relation with content words; 2) the initial learning of bound functional elements (e.g., endings such as –ing in English and –er in French) and their morphological relations with the stem (e.g., walk_walk-ing_walk-ed). For 1), we will test the hypothesis that the combined properties of weak word forms and high frequency for function words (relative to content words) enable infants to perceive them as functional elements and to use them to discover grammatical properties of content words (e.g., using determiners to categorize the adjacent word as a noun, “a/the dog”, “a/the cat”). To precisely study these properties, we will create artificial languages containing novel words, with careful manipulation of word forms and frequencies. Perceptual experiments using these materials will be conducted with one-year-olds. For 2), novel words with a familiar French ending –er and with an artificial ending will be used to test how preverbal and early verbal infants learn such endings and the morphological variation of related words. Across experiments, varying training conditions with novel word stems and endings will be used to examine input factors. We will test the hypothesis that the output of distribution-based morphological learning guides infants’ subsequent learning of word meaning. That is, infants first learn that certain forms are morphologically related (e.g., walk-walking), which then enables them to expect all forms of this variation to have the same core meaning. This hypothesis differs from the standard view that children first learn the meaning of individual words before interpreting (at a much later age) their internal morphological structure. Both 1) and 2) will test more than the learning of specific items and their relations. They will test infant’ ability to generalize structures at the abstract level. The studies will yield a better understanding of the mechanisms underlying early language development, in particular, the initial acquisition of abstract morpho-syntactic structures. They will contribute important data to the larger debate on the nature and origin of syntactic knowledge in infants.