Abstract
The current study compared two types of transducers of respiratory movements used for psychophysiological recordings, evaluating their performance in capturing and reproducing variations in underlying respiratory movements. We examined a newly developed air-filled bellows-type transducer and compared its performance against the carbon-film transducer, which is currently used in polygraph examinations for criminal investigations in Japan. An experiment using a calibrator to control underlying movements revealed that the performance of the air-filled bellows-type transducer was superior to that of the carbon film-type transducer in capturing the morphology of respiratory waveforms as well as variations in their amplitude. A polygraph experiment (n=19) demonstrated that the air-filled bellows-type transducer produced differences with larger effect sizes between critical and non-critical items in respiratory measures compared with the carbon-film type transducer. These results indicated that the air-filled type transducer exhibited superior performance for the recording of respiratory movements.
