In all human languages, we find words that are similar in some respect or another – usually because they are morphologically related. If speakers wish to determine the degree of similarity between two morphologically related forms, they must decide which elements to compare. Perhaps the most intuitive approach would be to compare the segments, and determine the degree of featural similarity they display. This approach might be thought of as ‘segmental comparison’. A schematic representation for two forms undergoing segmental comparison is given below.

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An equally plausible although less intuitive alternative is also available – prosodic elements could be compared. For example, the most prominent syllable node of each form might be compared, or the main-stressed nucleus of each form might be compared. This approach might be called ‘prosodic comparison’. Importantly, prosodic comparison might result in the comparison of elements that are associated with very different segmental melodies – for example, imagine a pair of words in which a given prosodic role (for example, head of prosodic word) has a different location in each form. Such a situation might occur in a language where stress shifts under affixation; in such a case, the linear order of segments would remain the same in both words, but the location of the prosodic heads would differ. A schematic representation of this sort of situation is given below.

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In this paper, I will consider just such a language – the Saipanese dialect of Chamorro – and demonstrate that the phonology of this language requires both segmental and prosodic comparison. This characteristic of the sound pattern of Chamorro holds great significance for theories which attempt to formalise phonological similarity effects, such as Steriade's (1996) theory of Paradigm Uniformity, Kenstowicz's (1995) theory of Uniform Exponence and McCarthy & Prince's theory of Correspondence (McCarthy & Prince 1993, 1994, 1995, McCarthy 1995). For simplicity of exposition, from this point on my analysis will be cast in terms of the theoretical framework of correspondence (discussed below). It should be remembered, however, that the main result of this analysis – the existence of prosodic phonological comparison – is relevant to any theory which seeks to give a comprehensive treatment of phonological similarity effects.