The differential categorization of identical stimuli depending on the presence of a prime is described as a perceptual divergence effect. We examined whether native listeners of the Berlin vernacular of German categorized identical acoustic stimuli differently in the explicit context of the names of two different districts of Berlin, assuming that listeners infer social information and linguistic stereotypes based on the names of these neighborhoods (Kreuzberg vs. Zehlendorf). All listeners categorized natural acoustic stimuli with synthetic fricatives synthesized along a continuum ranging from /ç/ to /ʃ/ as either Fichte /fɪçtə/ (`spruce') or fischte /fɪʃtə/ (1st person sg. `to fish'). This variable was chosen because many young multiethnic speakers of Berlin German pronounce /ç/ as [ʃ] or [ɕ], and this alternation is highly associated with speakers with a migrant background from Kreuzberg. Data were gathered in a forced-choice identification task, and, for a subset of the participants, reaction times (RTs) were also gathered. Results indicate a differential categorization pattern depending on (1) the copresented information, i.e., Kreuzberg, Zehlendorf, or none (control), and (2) the age of the listeners, with older listeners being more affected by the co-presented information. While older listeners categorized significantly more /ʃ/ sounds in the context of Kreuzberg than in the control or Zehlendorf condition, younger listeners rated most /ʃ/ sounds in the control condition (no added information). Results are interpreted in terms of a potential sound change in progress: the loss of the phoneme contrast between /ç/ and /ʃ/.