Phonetically-based analyses of phonological phenomena typically leave much of the relevant phonetics out of the formal analysis. For example, Archangeli and Pulleyblank (1994) argue that there is a dispreference for high vowels with retracted tongue root, *[+high, -ATR]. This constraint is argued to reflect the articulatory difficulty involved in both raising the tongue body and retracting the tongue root, but this motivation is presented informally - only the constraint plays a role in the formalized theory.

I will present an analysis of vowel reduction as a case study of the benefits of formalizing phonetic motivations within phonological theory, and of the issues that arise. One of the main benefits is that most accounts of phonetic motivation appeal to just a few basic preferences such as effort minimization (ease of articulation) and maximization of the distinctiveness of contrasts (facilitating perception). This implies the possibility of replacing a large number of parochial constraints (such as *[+high, -ATR]) with a few highly general constraints (such as 'Minimize effort'), if these can be properly formalized (cf. Hayes 1999, Kirchner 1998).