Previous research suggests that infant perception of phonetic contrasts undergoes a reorganisation during the first year of life with universal sound discrimination from birth that adapts to the native phoneme contrasts around 12 months of age. This paper focuses on two closely related languages that crucially differ in the realisation of stop contrasts: (Standard High) German and Swiss German. The first employs a VOT contrast for tense/lax stops, the latter uses a length contrast to distinguish singletons and geminates.
In a habituation paradigm, German and Swiss infants aged 7, 11 and 15 months were tested on their ability to discriminate (a) VOT contrasts and (b) closure duration contrasts for labial stops. Results show that German infants discriminated the VOT contrast at all ages. Swiss German infants discriminated the VOT contrast at 11 months only. At 7 months, neither German nor Swiss German children discriminated the closure duration contrast, whereas both groups were able to perceive the contrast at 11 and 15 months of age. Our findings contribute to clarifying the so far inconsistent picture of infant perception of length contrasts. We discuss the findings critically with regard to the different dimensions of VOT and closure duration.