End-tidal PCO sub(2) as an index of psychophysiological activity during VDT data-entry work and relaxation

• Published in: Ergonomics 1994-01, Vol.37 (2), p.245-254
• Main Authors: Schleifer, L M, Ley, R
• Format: Article
• Language: English
• ISSN: 0014-0139

Eleven data-entry operators were monitored continuously for three consecutive, 6 hour work days under the following conditions: (a) during a self-relaxation baseline period; (b) during an abbreviated progressive muscle relaxation period; and (c) during a period of computer-based data-entry work. End-tidal PCO sub(2), respiration frequency, and cardiac inter-beat interval (a measure of heart rate and its variability) were monitored continuously during the three conditions of the study. Self-ratings of relaxation and tension were also monitored at periodic intervals. Consistent with a decrease in psychophysiological arousal, end-tidal PCO sub(2) and self-ratings of relaxation were significantly higher during progressive muscle relaxation than during baseline relaxation. Consistent with an increase in psychophysiological arousal, end-tidal PCO sub(2), cardiac inter-beat interval, and relaxation ratings during data-entry work were significantly lower than during either baseline relaxation or progressive muscle relaxation, while respiration frequency and tension ratings were higher. The findings indicate that end-tidal PCO sub(2) discriminates among different psychophysiological states, and that end-tidal PCO sub(2) may be useful in indexing the stress-health effects of human-computer interactions.