This is a question that comes up from time to time, and I see some people using it interchangeably, I see this in the scientific literature and I see it in every day conversations and practice. So, what gives?
Let’s first look at the dictionary definitions:
1 [more dominant; most dominant]
: more important, powerful, or successful than most or all others
- The company is now dominant in the market
2 most common
- The dominant [=prevailing] language/religion of the country
3 biology : causing or relating to a characteristic or condition that a child will have if one of the child’s parents has it
- dominant genes
Proficient: (also from the learners dictionary)
[more proficient; most proficient]
: good at doing something : skillful
- a proficient reader
- He has become very proficient at computer programming.
- She is proficient in two foreign languages.
So, these aren’t exactly the same. In the work that I have done in language and language impairment, my collaborators and I try to distinguish between the two. Why does it matter?
I think especially in research and clinical work in language impairment it’s important to separate out the two. Children with typical development may demonstrate dominance in one language or another (or both), and at the same time they may have high levels of proficiency in both their languages. That is, they can be highly proficient users of both their languages at yet have MORE dominance in one of their languages.
In contrast children with language impairment demonstrate low proficiency in both their languages (not in every domain of course, they may show relative strengths in some aspects of language). At the same time they can be stronger (within their own performance) in their first language or in their second language or in both of their languages.
I think we can get into trouble when we assume that low proficiency in one language means dominance in the other. It doesn’t. We CAN have kids who show low proficiency in L1 and high proficiency in L2 and are dominant in L2. We can also have kids who show low proficiency in both and have dominance in only one language. We can have those who have high proficiency in both and be more dominance in one. The danger with conflating the two terms (and therefore measures) is that it could lead to bad decisions.
If the assumption is that a child with low proficiency in one language is therefore dominant in the other, it could lead to delaying of services (RTI, speech or language intervention, reading intervention) if they have a true impairment. It might be assumed that low proficiency in one language equals low proficiency overall, and this assumption might lead to a diagnosis of a language impairment even if the child actually does NOT have an impairment (and is actually highly proficient in the other language). If a child is not very proficient in either language, this may lead people to say something like, they have no language (I totally hate that, unless they are in a coma, I don’t know how this could be). This assumption might lead to giving parents suggestions like only using one language because the child has incomplete language acquisition in both. Like monolingualism would be the cure for language impairment. UGH!
So, don’t get rid of one term. We need both proficiency (to measure how good children are at each language) and dominance (to determine which is the stronger of the two languages for a given bilingual child).