engleski

Habituation of Cardiac Activity during an Exam

It is well known that exams usually are very stressful situations involving emotional and mental effort. Most of studies concerning exam stress are based on various questionnaires administered before and after exams. There are very few studies which included observations of changes in psychophysiological variables during exams. The aim of this investigation was to register changes in sinus arrhythmia during a difficult exam, because it is well known that various aspects of cardiac activity are good indicators of stress. For the purpose of this study, R-R cardiac intervals were continuously recorded during the whole exam. Seven students voluntarily took part in this investigation, where they were fitted with three electrodes for continuous recording of R-R intervals by the use of Power-Lab recording system. The results were analysed by the use of spectral analysis, which gave individual frequency spectra before, during and after the exam over five minute periods. Power spectrum parameters (SMI indices) were worked out for low (0.02-0.06 Hz), medium (0.07-0.14 Hz) and high (0.15-0.50 Hz) frequency bands. Spectral analysis showed suppression of low and medium frequency bands during the exam, which was due (as interpreted) to emotional and mental stress, respectively. Comparison of suppression of low and medium frequency bands showed a higher suppression in the medium frequencies, showing thus, that the mental component of stress was more prominent during the exam than emotional. The analysis also showed the total stress to be the highest during the first five minutes of the exam. After that, the parameters showed gradual decrease in both emotional and mental stress, which was attributed to the subject's habituation to the exam situation. Changes in the SMI index, for high frequency band, were interpreted as the effects of breathing and speech motor activities.

stress; cardiac activity; cardiac R-R intervals; habituation

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