Dean A. Pollina
Douglas A. Vakoch
Lee H. Wurm
Dept. of Psychol., State Univ. of New York at Stony Brook, Stony Brook, NY 11794-2500
Variation in the truth value of propositions has been shown to yield changes in cognitive event-related potentials (ERPs) [D. A. Pollina and N. K. Squires, Psychophys. 30, S52 (1993)]. Given the connection between the arousal of the central nervous system and peripheral systems, the same paradigm that was used to detect many-valued beliefs via ERPs was used to detect degree of belief by an acoustical analysis of the voice. Degree of belief was manipulated by having subjects solve a murder mystery, after which they learned facts associated with three people: (1) the person they most suspected of committing the murder, (2) the person they judged next most likely to be the murderer, and (3) the person they knew could not be the murderer. Articulatory precision of subjects' utterances was measured by formant location and spectral composition [F. J. Tolkmitt and K. R. Scherer, J. Exp. Psychol. Human Percept. Perform. 12, 302--313 (1986)]. These measures were related to the degree to which subjects believed each statement to be true.