Commentary on Daelemans, Gillis, and Durieux 
Jonathan Kaye 1 
(School of Oriental and African Studies) 
The authors turn an Instance-Based Learning model (IBL) loose on some Dutch stress 
data. They come to a number of conclusions regarding the models that could underlie 
human stress acquisition, to wit, "... tree building operations proposed in learning the- 
ories for metrical phonology are not necessary for learning stress assignment" (p. 449) 
One assumes that this conclusion carries over to grid building as well. A second 
conclusion is that "... phonemic representations yield significantly better results \[in 
learning Dutch irregular stress/JK\] than the encoding in terms of syllable weights" 
(p. 449) In my opinion, the authors have failed to justify either conclusion. 
Their work involves modeling the acquisition of Dutch stress. Specifically, the 
learning task is to assign Dutch input words to one of three categories: PEN, FIN, or 
ANT. Since systems very different from the Dutch one exist, the requirements of learn- 
ing systems based exclusively on it can be carried over to the more general problem 
of human stress acquisition. Crucially, the authors do not consider the assignment of 
secondary stress or any of the other types of stress systems attested in the literature. 
The authors consider three methods of encoding input forms: (1) syllable weights, 
(2) the "phonemes" of the rhyme projection, (3) a plain "phonemic" transcription of 
the word. The authors test these three methods with respect to Dutch stress placement. 
Research on human stress systems has failed to turn up examples where the segmental 
content of a form is relevant to general patterns of stress assignment. Statements of the 
form, "assign stress to the final nucleus unless it contains "i" in which case assign stress 
to the penultimate nucleus" are unattested. Accordingly, the conclusion of Daelemans 
et al. that "... the phonemic representations yield significantly better results than the 
encoding in terms of syllable weights" (p. 449) is surprising. Daelemans et al. note 
that for regular stress assignment (i.e. stress assignment based on syllable weight) the 
first encoding is the most successful. Encodings 2 and 3 only come into their own 
with respect to lexical exceptions. The authors fail to distinguish two very different 
operations: (1) the assignment of stress based on phonological structure and (2) the 
identification of lexical exceptions. While segmental content is irrelevant for the first 
task, it is essential for the second. It is clear that segmental material is required for 
the assignment of arbitrary marks (\[-ex\], LF, etc.) because we must know to which 
lexical items these diacritical marks are assigned. What emerges from the discussion 
is that the irrelevance of segmental material to stress assignment is supported by the 
current study. Indeed, there are many examples of stress systems where 100% of the 
lexical items belong to the "R" (regular) class. I know of no stress systems that are 
entirely based on patterns requiring "phonemic" information. 
In conclusion, the restricted nature of the model deprives the theoretical claims of 
much of their relevance. Failure to distinguish stress assignment based on constituent 
structure vs. stress assignment as a property of certain lexical items attenuates the 
authors' claims about the relevance of the encoding methods. I believe we can remain 
secure in the belief that segmental material is irrelevant to stress assignment. 
1 Department of Linguistics, School of Oriental and African Studies, Thornhaugh Street, Russell Square, 
London WCIH 0XG, U.K. 
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