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4.Conclusions and discussion

Let us now try to formulate answers to the research questions that we asked in section 2. The first two questions, which I will attempt to answer together, asked whether the domain-final boundary tones are contiguous categories along a single tonal dimension, and map onto the command, continuation and question meaning in a one-to-one fashion. The results of our experiments clearly indicate that this is indeed the case. Our listeners had no difficulty in using the three response alternatives provided to them. When the terminal pitch was lower than the preceding pivot point in the contour the responses were almost unanimously for ‘command’. When the IP-final pitch was higher than the preceding pivot point, the incidence of ‘continuation’ responses increased up to and including step 4, and decreased for higher terminal pitches which were more readily identified as questions as the terminal pitch was higher. Although there was always some ambiguity between the ‘continuation’ and ‘question’ alternatives, the results clearly indicate that ‘continuation’ is signaled by moderate final pitch, and question by (extra) high pitch.

The latter finding corresponds with our suggestion that asking a question involves a higher degree of appeal by the speaker to hearer than asking the listener’s continued attention. We may also note that our result clashes with Caspers (1998). She found that the intermediate final pitch (or high level pitch in her experiment) was unambiguously identified as continuation; extra high final pitch ambiguously coded either continuation or question. Comparison of Caspers’ and our own results is hazardous since the utterance-final tone con­figurations differ, not so much at the underlying tone level, but at the surface. It seems to me that the discrepancy between Caspers’ and our own findings can be resolved if we accept the possibility that Caspers’ extra high terminal pitch was simply not high enough to elicit the 80% ‘question’ responses that we got in our experiment.

The results so far concur with van Heuven & Kirsner (2002). However, we may now go on to consider the third, fourth and fifth question, which asked where the category boundaries are located along the final pitch continuum between ‘L%, ‘%’ and ‘H’, in the binary and ternary response tasks, and to what extent the boundaries coincide with a peak in the discrimination function.

The results obtained in the binary (‘command’ ~ ‘no command’) and ternary (‘command’ ~ ‘continuation’ ~ ‘question’) identification tasks are virtually the same, yielding the same location of the boundary (at step 2.7) separating the ‘command’ category from the rest of the stimulus continuum. However, a very unstable boundary is found in the binary ‘question’ ~ ‘no question’ task (at step 3.6), which is reflected in the poorly defined boundary separating the ‘continuation’ and ‘question’ categories in the ternary response task (at step 7.2). Moreover, we have seen that the category boundary between ‘command’ and ‘no command’ coincides with a huge peak in the discrimination function. Although there is a modest local maximum in the discrimination function that may be associated with a boundary between ‘continuation’ and ‘question’, this peak is not very convincing.

I take these findings as evidence that there is a linguistic, or phonological, categorization of the IP-final boundary tone continuum in just two types, which is best characterized as low and non-low. The low boundary tone signals dominance or superiority on the part of the speaker. This is the boundary tone that is suited for issuing statements and commands. The non-low boundary tone signals subservience of the speaker to the hearer; the speaker appeals to the hearer for his continued attention or for an answer to a question.

The non-low part of the boundary opposition, however, represents a gradient, paralinguistic continuum between a moderate appeal (asking for the hearer’s continued attention) and a stronger appeal (asking the hearer for a verbal reply to a question). Here the lower terminal pitches are associated with weaker degrees of appeal (or subservience), and the higher levels with strong appeal, but in a continuous, gradient, non-phonological manner.

Our results indicate that earlier findings reported by Remijsen & van Heuven (1999, 2003) are to be viewed with caution. We now know that the proper task to be imposed on listeners should not be to decide whether the stimulus is a statement (or a command) versus a question. If binary response alternatives are required, then the categories should be ‘statement’ versus ‘no statement’ but a better procedure would be to ask the listener to respond by choosing from three categories: ‘statement’ (equivalent to ‘command’ in our experiments ~ ‘continuation’ ~ ‘question’. Had such precautions been taken by Remijsen & van Heuven, their category boundary would have been much better defined with less listener-individual variation.

Methodologically, we argue that the classical identification-cum-discrimination paradigm is a useful diagnostic tool in intonation research which allows linguists to decide experimentally whether a melodic contrast is categorical and therefore part of the phonology, or continuously gradient and therefore phonetic or even paralinguistic.