Many modern Arabic dialects exhibit asymmetries in the direction of emphasis (for most dialects, pharyngealization) spread. In a dialect of Yemeni Arabic, emphasis has two articulatory correlates, pharyngealization and labialization: within the phonological word, pharyngealization spreads predominantly leftward, and labialization spreads rightward, targeting short high vowels. Since asymmetries in the directionality of spread of a secondary feature are phonetically motivated and depend on whether the feature is anchored to the onset or the release phase of the primary articulation, it is argued that the unmarked directionality of spread should be encoded in the phonology as a markedness statement on that feature.