This paper investigates the occurrence of inflected predicative adjectives, an optional yet distinguishing feature of German dialects spoken in southern Switzerland. We provide an in-depth analysis of the patterns of change of this morphosyntactic marker with a particular focus on extralinguistic factors. Historical records from 1950 were compared to contemporary data collected from 192 speakers across 49 localities in 2020–21. Our results corroborate previous reports indicating a substantial, real-time decline in inflected forms. Logistic mixed-effects modeling suggests that the inflection of predicative adjectives occurs more frequently among speakers who report tight social networks, have a strong local dialect identity, and regularly use one or more Romance languages. These findings support the claim that tight social networks and local dialect identity construction may lead to the preservation of conservative grammatical forms. Additionally, the effect of Romance languages highlights the role of transfer phenomena induced by language contact.

Heritage language acquisition has been characterized by various asymmetries, including the differential acquisition rates of various linguistic areas and the unbalanced acquisition of different categories within a single area. This paper examines Arabic heritage speakers’ knowledge of subject–verb agreement versus noun–adjective agreement with the aim of contrasting their distributions and exploring areas of resilience and vulnerability within Arabic heritage speech and their theoretical implications. Two oral-production experiments were carried out, one involving two picture-description tasks, and another requiring an elicited narrative. The results of the study show that subject–verb agreement morphology is more maintained than noun–adjective morphology. Moreover, the unmarked singular masculine default is more robust than the other categories in both domains and is often over-generalized to other marked categories. The results thus confirm the existence of these asymmetries. We propose that these asymmetries may not be explained by a single factor, but by a complex set of morphological, syntactic, semantic, and frequency-related factors.