Analysis of the data

The data collected were subjected to various qualitative and quantitative analyses that were based on (a) a descriptive framework of the major developmental milestones established for the acquisition of either language, and (b) a descriptive framework of the grammatical properties of DGS and German. For each language we elaborated diagnostic criteria that would allow for the assessment of the competences available. The systematic analysis of the data has been guided by the following questions:

• - What is the structure available to the participants at the onset of the study?
• - If they are not fully competent at the onset of the study, how far do they progress in the time span covered by this study?
• - If their productions contain evidence of language mixing, what are the linguistic properties affected and does language mixing change over time?

Data samples analysed. In our selection of the files subjected to analysis we were guided by the following hypotheses. Given the rather advanced average age of the participants at the onset of the study, we expected that they would demonstrate full competence of the sentential structure of DGS in the first recording (file 1). To track down potential further development we decided to additionally include a sample collected a year after the onset of the study (file 3) in our analysis. Because mastery of discourse constraints on the use of linguistic devices is known to represent a protracted development in sign language acquisition we advanced that changes in the participants’ command of DGS would become apparent at this level.

As for written German, we expected participants to vary substantially regarding their competence level at the onset of the study and the progress they would make subsequently. To better track down potential changes in the participants’ learner grammars we decided to subject the five samples elicited on the basis of the frog story to systematic scrutiny. The selection of a larger number of samples for German than for DGS would also allow us to look at a larger time span for German, which we deemed necessary in order to assess a development we expected to proceed at a much slower pace in German than in DGS.

Table 2.7: Longitudinal investigation at the Berlin programme: files covered in this study.

A note on productivity vis-a-vis patterns of emergence. Following the dynamic approach elaborated in section 2.2.3.1 we were not only interested in the systematic characteristics of the respective learner grammar, but also considered exceptions or marginal phenomena that might give a cue about potential upcoming changes and reorganisations. From this perspective, as remarked upon by Tracy (1994/5: 198) “what matters therefore is not absence vs. presence as such but an overall pattern of emergence, something equivalent to the biologists’ fossil record.” As outlined in section 2.2.3.1, the role of marginal phenomena can only be interpreted a posteriori, against the backdrop of the overall development.