A huge variation in the rate of vocabulary and language development can be observed in children , and parents/caretakers should not expect all children to develop at the same rate .The development of speech is dependent on the environment that the child is brought up in especially the social interactions the child has with the members of the household. A child who is spoken to often and is exposed to the daily routine of the house/ neighborhood develops its own interpretation and relation between words and actions.
Kids typically try to use the type of communication conventional in their community for example a child brought up in a active Spanish household may start waving its arms to communicate before actually forming the words when it sees the people in its orbit doing so. A child brought up in a silent household may not speak early as it has negligible exposure to the use of verbal or non verbal communication. The Motor function development in the child also impacts the rate of speech development. Children who are read to often or encouraged to speak are seen to make better effort at communication rather than those children left to their own devices.
It is also found that children of working parents, who are left in day care, adopt the speech mannerisms they are exposed to in the day care center. There are instances when children develop speech when they find they are not getting what they want or need and vice versa. There also needs to be allowances made such as the health of the child and its behavior patterns. The development of speech is also dependent on the interest displayed by the child in learning and participating in activities like play or reading. Therefore we can see that children develop at different rates depending on their environment and internal biological development. The exposure that a child is given compounded with the pace of motor functions impact the age of speech for different children.
Wegner, Lynn (2007).Screening for Speech and Language Delay in Preschool Children: More Answers Are Needed. Pediatrics. 533-534.
Nelson, Heidi D., Nygren, Peggy, Walker, Miranda, & Panoscha, Rita (2007). Screening for Speech and Language Delay in Preschool Children: Systematic Evidence Review for the US Preventive Services Task Force. Pediatrics, 298-319.
Wertsch, James 1985. Vygotsky and the Social Formation of Mind. Cambridge, MA: Harvard University Press.