Department of Linguistics

Distinctiveness constraints favor maximization of the perceptual differences between contrasting sounds - less distinct contrasts incur more severe constraint violations. Perceptually indistinct contrasts are disfavored because they increase the likelihood of confusion on the part of listeners. The preference for distinctive contrasts can be observed in the typology of segment inventories. For example, there is a cross-linguistic preference for front unrounded and back rounded vowels because these yield more distinct contrasts in second formant frequency than front rounded or back unrounded vowels. Distinctiveness constraints also give rise to positional neutralization effects where a contrast is neutralized in environments where it would not be sufficiently distinct. E.g. stop voicing contrasts are neutralized in final position where crucial Voice Onset Time cues are not available. However, if distinctiveness constraints interacted freely with other phonological constraints, we would expect to find additional effects that are in fact unattested. For example, articulatory markedness constraints could motivate wholesale reorganization of vowel inventories depending on consonant context. We would also expect to find 'positional enhancement' as a counterpart to positional neutralization: enhancement of contrasts precisely where they would otherwise be neutralized due to insufficient distinctiveness. This phenomenon is not attested in a general form. These limitations provide evidence for a model according to which the basic role of distinctiveness constraints lies in deriving an inventory of contrasting segments which serves as the 'alphabet' from which underlying forms are constructed, much like a phoneme inventory. This process is the locus of most enhancement effects. The distinctiveness constraints evaluate contrasts between words only to check that the contrasts are adequately realized on the surface - if not, they are neutralized (giving rise to positional neutralization). However, distinctiveness constraints play no other role in the mapping from underlying to surface form. That mapping is governed by constraints requiring faithful realization of the underlying contrasts in conflict with markedness constraints (articulatory constraints, metrical constraints, etc).