Accommodation of end-state comfort reveals subphonemic planning in speech.

Applying the 'end-state comfort' hypothesis of Rosenbaum et al. [J Exp Psych Learn Mem Cogn 1992;18:1058; Acta Psychol (Amst) 1996;94:59] to tongue motion provides evidence of long-distance subphonemic planning in speech. Speakers' tongue postures may anticipate upcoming speech up to three segments, two syllables, and a morpheme or word boundary later. We used M-mode ultrasound imaging to measure the direction of tongue tip/blade movements for known variants of flap/tap allophones of North American English /t/ and /d/. Results show that speakers produce different flap variants early in words or word sequences so as to facilitate the kinematic needs of flap/tap or other /r/ variants that appear later in the word or word sequence. Similar results were also observed across word boundaries, indicating that this is not a lexical effect.