A talker's ability to evaluate certain aspects of his articulatory behavior was examined with magnitude-estimation methods. The task was to generate patterns of activity appropriate to the production of bilabial stop consonants, both in syllable initial (hold plus plosion) and syllable final (hold only) position, as well as some analogous nonspeech activities. During all activities, a measurement of air pressure in the oral cavity was obtained. The subjects monitored their production both in terms of pressure in the oral cavity, and degree of effort used in production. The findings indicate that subjects' estimation of the subjective magnitude of “pressure,” or “effect,” increases approximately as the 1.4 power of the intraoral pressure, a finding similar to other reported production magnitude functions. The absolute pressures used by the subjects at their “standard” levels in the plosion mode approximated values reported for stop consonant production, with higher pressures for /p/ than for /b/. In the unexploded mode of production, pressures tended to be higher, with /b/ pressures exceeding those used to produce /p/. [This study was supported in part by the Air Force Cambridge Research Laboratories under contract; and by a NIDR Research Career Development Award (RLR)].