Sentence:  Whilst the principle of <WSD>linguistic imbalance</WSD> is confirmed by a number of researchers, Ridley and Singleton (1995), amongst others (e.g. Kellerman & Sharwood Smith, 1986), point out that the perception of language distance is at least an equally important factor. 
Meaning of the word marked with <WSD> tags:  The differential in skills of a polyglot among the languages they know.