Final answer:
There is ongoing debate about whether the language systems (syntax, morphology, etc) interact in development and should be targeted together in therapy.
Step-by-step explanation:
The question of whether the language systems (syntax, morphology, etc) interact in development and whether they should be targeted together in therapy is a complex one. Some researchers argue that the language systems do not interact and should be targeted separately in therapy, while others believe that they do interact and should be targeted together.
One piece of evidence that suggests the language systems do not interact is the observation of certain language impairments known as V impairment (difficulty using verbs) and N impairment (difficulty using nouns). These impairments can occur independently, indicating that the two language systems may develop separately.
However, it is important to note that there is also evidence supporting the idea that the language systems do interact. For example, teaching sign language and spoken language together to children has been found to provide deeper cognitive reinforcement and greater chance of recall. This suggests that the two language systems may work together to enhance language development.