In this question we wish to get a sense of whether simplification in speech occurs when speakers deduce comprehension issues from their interlocutor. This phenomena is sometimes described as foreigner-directed speech (FDS).
We interpret the absence of FDS as one way of inferring that the people in the Neighbour Group comprehend the language of the Focus Group well enough.
The answer to this question is treated as one of a number of factors that play a role in affecting the outcomes of language change. The factor by itself is likely unable to affect outcomes, but in combination with other factors, is thought to play a role.
Foreigner-directed speech (FDS) is a type of simplified speech that “native speakers” of a language direct at “non-native speakers”.
One way to infer foreigner-directed speech is by thinking about any relevant characteristics of child-directed speech in the community (e.g. frequent use of imperatives as documented for Swahili (Atlantic-Congo, cf. Deen 2005) and Murrinhpatha (Southern Daly, cf. Forshaw et al. 2017) and whether they happen to occur in interactions between Focus and Neighbour Group in this domain, and from the perspective of the Focus Group.
Features of English FDS include:
“Proportion of adult learners” is a factor that is sometimes raised in discussions of language contact and change. The implication is that these adult learners are “incomplete learners” of the language under investigation. An important component of this “incomplete learner” picture is, then, what input these adult learners are receiving, and how they are learning. This question aims to touch upon this by raising the issue of FDS.
A classic study on similarities between foreigner- and child-directed speech based on English is Uther et al. (2007). The similarities reported in this and similar studies are, however, far from universal. In the Kaluli speech community of Papua New Guinea, for instance, simplification patterns in child-directed speech are purposely avoided because considered to be detrimental to effective language acquisition (Schieffelin 1990). A recent study which brings cross-linguistic corpus evidence in support of the idea that foreigner-directed (written) speech is simpler than native-directed (written) speech is Berdicevskis (2020).