speakers often use the phonological systems of their native language, meaning they must learn to recognize such diaphonic correspondences in the speech of others to facilitate the mutual intelligibility of a working pidgin. proposes that rule differences can be used to determine the distance a particular utterance has between a post-creole continuum's acrolectal and basolectal forms. points out that mesolectal varieties often have features not derivable from such rules. Cognitive reality The status of panlectal and polylectal grammars has been subject to debate amongst generative phonologists since the 1970s; one of the foremost areas of contention in regards to diaphonemes and diasystems is whether they reflect the actual linguistic competence of speakers. William Labov, although warm to the construction of a panlectal grammar, argued that it should be based in speakers' linguistic competence. Peter Trudgill argues against the formation of diasystems that are not cognitively real and implies that polylectal grammars that are not part of native speakers' competence are illegitimate. Similarly, cautions that polylectal grammars are only appropriate when they "result in claims about speaker-hearer's capabilities..." Although no linguists claim that panlectal grammars have psychological validity, and polylectal diasystems are much more likely to be cognitively real for bilingual and bidialectal speakers, speakers of only one dialect or language may still be aware of the differences between their own speech and that of other varieties. Take, for example, the word house, which is pronounced: in Buffalo in Toronto and Washington, D.C. in Philadelphia in Charlottesville. Native speakers are able to calibrate the differences and interpret them as being the same. A similar issue occurs in Chinese. When a "general word," is shared across multiple mutually unintelligible dialects, it is regarded as the same word even though it is pronounced differently depending on a speaker's region. Thus a speaker from Beijing and Nanking may pronounce 遍 ('throughout') differently, ( and , respectively), though they still regard the differences as minor and due to unimportant accentual differences. Because speakers aren't normally able to hear distinctions not made in their own dialect (for example, a speaker from the Southern United States who does not distinguish between pin and pen won't hear the distinction when it's produced by speakers of other dialects), speakers who can hear such a contrast but don't produce it may still possess the contrast as part of their linguistic repertoire. In discussing contextual cues to vowel identifications in English,