Describe two accounts of how semantic development takes place

What will be an ideal response?

Young children's fast-mapping is supported by a special part of short-term memory, a phonological store that permits us to retain speech-based information. The faster preschoolers can recall a just-presented sequence of nonsense words (a measure of phonological memory skill), the larger their current vocabulary and the greater their vocabulary growth over the following year. This suggests that a child with good phonological memory has a better chance of transferring new words to long-term memory and linking them with relevant concepts.
By the end of the second year, phonological working memory is so good that toddlers can recognize familiar words on the basis of their initial sounds. Being able to identify a word rapidly on the basis of initial sounds has clear advantages: It frees working memory for other language tasks, such as comprehending longer and more complex strings of words.
Young children figure out the meanings of words by contrasting them with words they already know and assigning the new label to a gap in their vocabulary. Over time, they refine the word's meaning, striving to match its conventional use in their language community. Early in vocabulary growth, children adopt a mutual exclusivity bias—the assumption that words refer to entirely separate (nonoverlapping) categories.
Once toddlers have acquired about 75 words, a shape bias is clearly evident: Previous learning of nouns based on shape heightens attention to the shape properties of additional objects. As a result, toddlers readily master additional names of objects, and vocabulary accelerates. Preschoolers discover many word meanings by observing how words are used in syntax, or the structure of sentences—a hypothesis called syntactic bootstrapping. Young children also take advantage of the rich social information that adults frequently provide when they introduce new words.
An alternative perspective is that vocabulary growth is governed by the same cognitive strategies that children apply to nonlinguistic stimuli. A recent account, called the emergentist coalition model, proposes that word-learning strategies emerge out of children's efforts to decipher language. Children draw on a coalition of cues—perceptual, social, and linguistic—which shift in importance with age.