Troughs, defined as a discontinuity in anticipatory coarticulation (Perkell 1968), have been shown to occur in the tongue body (TB) in /ipi/ and lips in /usu/. In V1CV1 contexts articulators retract from their vowel target during C when not active during C. We investigate the trough phenomenon by testing three hypotheses: (1) high intraoral air pressure during the consonant pushes TB down; (2) absence of vowel articulator activation during C in VCV causes TB to move to the neutral position; (3) the trough is a gesture in itself. Electromagnetic articulometer (EMA) data of the tongue, lips, and jaw were tracked for a trained phonetician producing non-words and real words, varying vowel context and the place, manner, and consonant length. For H1, /iCi/ productions with C={/p,f,m/} and three C durations were studied. For H2, /h/ and /ʔ/ in /iCi/ were examined. Troughs were found in all the labials but not in /h, ʔ/, disproving hypothesis 2; trough magnitude decreased in the order: /f/ > /p/ > /m/, disproving hypothesis 1. Trough magnitude increased with C duration, consistent with H3. Results from asymmetric vowel contexts also support H3, and will be discussed within the context of Articulatory Phonology. [Work supported by NIH.]