A Developmental Perspective on Language Acquisition 33components of linguistic form, content, and use, which will be
addressed in the other chapters of this book.
In addition to individual differences in the rate of early
language development, variation has also been described in
early word forms and functions. Characterizations of these early
differences have included Referential and Expressive Styles
(Nelson 1973). For example, referential children might tend to
use language to label objects in their environment and acquire
more noun forms to do so. Expressive children might tend to
use language for more personal-social uses and acquire more
words for greetings such as “hi” and “bye.” The topic of individual
differences in early language development is beyond the scope
of this chapter, but the interested reader is referred to Goldfield,
Snow, and Willenberg (2017) for further information.
By the end of the One-Word Stage, children often combine
words to form their first multiword utterances. At this stage,
children use language to express different meanings and content
categories making a smooth transition into the Two-Word
Stage (Gerber and Prizant 2000), which lasts from about
18 to 24 months. During this period, the infant-toddler combines
words and shares experiences symbolically. For example, the child
could say “drink juice” while pretending to give a doll real or
imaginary juice. Of note, the vast majority of the child’s word
combinations are characterized by correct word order (as in the
foregoing example) marking the onset of semantic-syntactic rules
in which the child uses word order to express many of the same
meanings observed at the One-Word Stage. For example, the child
can now say “my juice” instead of being limited to single words
such as “mine” or “juice.” A marked explosion in both receptive
and expressive vocabulary development usually occurs during this
time period. In addition, children understand word combinations,
simple directions, and wh-questions involving the words “who,”
“what,” and “where”; they comprehend between 150 and