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Stress-related changes of saliva cortisol in VDU operators
150 respiratory cycle duration (trot) , inspiratory time (ti) , expiratory time (te), blood pressure (BP) and heart rate (HR) were measured (pneumotachograph, Pehfiz method of non-invasive BP recording). The mean values and the spectra of fluctuations in circulatory and respiratory parameters were calculated. The circadian rhythm was found in BP and HR but not in ttot. ti, t e (Halberg cosinor analysis). Interindividual variation of ttot, t i and t c was large (range of mean trot, 2.7_+ 10.4 s) but intraindividual variations in ttot were small (5.4 + 27.9%) during 24 h. The spectra of BP, HR, ttot, t i and t e remained stable during the 24 h period. It can be speculated that in conscious man over 24 hs, nervous activity of respiratory and cardiovascular centra remained stable.
STRESS-RELATED CHANGES OF SALIVA C O R T I S O L IN V D U O P E R A T O R S G. Schreinicke, A. Hinz, B. Hiiber, J. Kratzsch and S. Heerden In the field of work physiology, catecholamines and cortisol are used as strain indicators because their production increases under mental strain. The secretion of catecholamines and of cortisol can be determined in the blood plasma. In studies on mental load, urine specimens are preferred because the invasive method, due to its feedback, is seldom accepted under real working situations. However, short-term or 'peak' stress cannot be determined by measuring catecholamines in urine. For this reason, we investigated the production of saliva cortisol and its relationship with other peripheral arousal parameters in a short-term stress situation. We examined 80 healthy male subjects who worked at a video display unit (VDU) for 30 rain. They were instructed to carry out a task with high speed and accuracy demands. Saliva specimens were taken before and after VDU work. Saliva cortisol levels were determined by means of a sensitive enzyme immunoassay. Additionally physiological parameters (heart rate, blood pressure, respiratory rate) and task performance were measured, and the subjects were questioned on their feelings of stress and psychovegetative disorders. Saliva cortisol concentrations were significantly increased after 30 min of VDU work. Heart rate, blood pressure and respiratory rate were also increased during the task. In persons with high heart rates and high blood pressure, levels of saliva cortisol increased significantly more during V D U work than in persons with lower heart rates and blood pressure. The result indicate that saliva cortisol is a useful strain indicator in short-term stress situations.
A L C O H O L AND I N F O R M A T I O N PROCESSING W. Sommer a, H. Leuthold a and M. Hermanutz b a University of Konstanz, Konstanz and b Police Academy, VS-Schwenningen, Germany
We studied the effects of acute alcohol intoxication in a double-blind Simon-type experiment. 30 min before testing 16 right-handed men (mean age) drank orange juice either plain or mixed with vodka. Blood alcohol concentration averaged 0.69 m g / m l . Fast and accurate two-choice responses were required according to the shapes of visual stimuli which were easy or hard to discriminate and presented lateral to fixation. We recorded midline ERPs against average mastoids from 5 electrodes and the lateralized readiness potential (LRP) from C3' and C4' (bandpass 0.01 to 40 Hz). Only error- and artefact-free trials were analysed. Alcohol diminished the effects of stimulus discriminability on the median RTs, but it produced neither changes in the strong effects of the correspondence between stimulus and response location nor overall group differences. Also, no alcohol effects were present in error rates. In ERPs, alcohol reduced the amplitudes of the occipital N2 and of the prefrontal P3a component. In the LRP, alcohol diminished both the early and late activation due to stimulus location and stimulus type, respectively. The P3b latency was sensitive to stimulus discriminability but was unaffected by alcohol. Thus, ERPs reveal alcohol effects on perceptual and motor processes which remain concealed when only behavioral measures are considered.
I N D I V I D U A L D I F F E R E N C E S IN SHORT-TERM MEMORY AND E V E N T - R E L A T E D POTENTIALS
W. Sommer, R.B. Freeman, H. Leuthold, P. Mikulics and S. Schweinberger University of Konstanz, Konstanz, Germany
In age-heterogeneous subject-groups, auditory memory span is inversely related to P300 latency in counting tasks. We studied the relationship between ERPs recorded in a memory task and measures of short-term memory (STM) performance in 24 students and scientists (range 22 to 36 years). Subjects performed (1), a recognition task for unfamiliar faces. We measured recognition performance (area below the ROCcurve), early and late P300 amplitudes and latencies during study and recognition and the amplitude difference between study phase ERPs according to subsequent recognition. (2), Capacity of short-term memory was measured in an auditoryverbal memory span task (forward and backward) and in a visual supra-span test. (3), Speed of memory search (Sternberg) was assessed for numbers and for familiar and unfamiliar faces and objects. Canonical correlation analysis of the variable groups showed that ERPs related to memory span only. This was due to the correlation of - 0 . 4 4 between the backward auditory-verbal span and the late P300 latency during recognition to faces judged as new. Thus, the relationship between individual STM capacity and P300 latency may be found also within subject groups that are homogeneous in respect to age and intelligence and it appears to be attributable to relatively specific processing aspects.
STRESS-RELATED CHANGES OF SALIVA C O R T I S O L IN V D U O P E R A T O R S G. Schreinicke, A. Hinz, B. Hiiber, J. Kratzsch and S. Heerden In the field of work physiology, catecholamines and cortisol are used as strain indicators because their production increases under mental strain. The secretion of catecholamines and of cortisol can be determined in the blood plasma. In studies on mental load, urine specimens are preferred because the invasive method, due to its feedback, is seldom accepted under real working situations. However, short-term or 'peak' stress cannot be determined by measuring catecholamines in urine. For this reason, we investigated the production of saliva cortisol and its relationship with other peripheral arousal parameters in a short-term stress situation. We examined 80 healthy male subjects who worked at a video display unit (VDU) for 30 rain. They were instructed to carry out a task with high speed and accuracy demands. Saliva specimens were taken before and after VDU work. Saliva cortisol levels were determined by means of a sensitive enzyme immunoassay. Additionally physiological parameters (heart rate, blood pressure, respiratory rate) and task performance were measured, and the subjects were questioned on their feelings of stress and psychovegetative disorders. Saliva cortisol concentrations were significantly increased after 30 min of VDU work. Heart rate, blood pressure and respiratory rate were also increased during the task. In persons with high heart rates and high blood pressure, levels of saliva cortisol increased significantly more during V D U work than in persons with lower heart rates and blood pressure. The result indicate that saliva cortisol is a useful strain indicator in short-term stress situations.
A L C O H O L AND I N F O R M A T I O N PROCESSING W. Sommer a, H. Leuthold a and M. Hermanutz b a University of Konstanz, Konstanz and b Police Academy, VS-Schwenningen, Germany
We studied the effects of acute alcohol intoxication in a double-blind Simon-type experiment. 30 min before testing 16 right-handed men (mean age) drank orange juice either plain or mixed with vodka. Blood alcohol concentration averaged 0.69 m g / m l . Fast and accurate two-choice responses were required according to the shapes of visual stimuli which were easy or hard to discriminate and presented lateral to fixation. We recorded midline ERPs against average mastoids from 5 electrodes and the lateralized readiness potential (LRP) from C3' and C4' (bandpass 0.01 to 40 Hz). Only error- and artefact-free trials were analysed. Alcohol diminished the effects of stimulus discriminability on the median RTs, but it produced neither changes in the strong effects of the correspondence between stimulus and response location nor overall group differences. Also, no alcohol effects were present in error rates. In ERPs, alcohol reduced the amplitudes of the occipital N2 and of the prefrontal P3a component. In the LRP, alcohol diminished both the early and late activation due to stimulus location and stimulus type, respectively. The P3b latency was sensitive to stimulus discriminability but was unaffected by alcohol. Thus, ERPs reveal alcohol effects on perceptual and motor processes which remain concealed when only behavioral measures are considered.
I N D I V I D U A L D I F F E R E N C E S IN SHORT-TERM MEMORY AND E V E N T - R E L A T E D POTENTIALS
W. Sommer, R.B. Freeman, H. Leuthold, P. Mikulics and S. Schweinberger University of Konstanz, Konstanz, Germany
In age-heterogeneous subject-groups, auditory memory span is inversely related to P300 latency in counting tasks. We studied the relationship between ERPs recorded in a memory task and measures of short-term memory (STM) performance in 24 students and scientists (range 22 to 36 years). Subjects performed (1), a recognition task for unfamiliar faces. We measured recognition performance (area below the ROCcurve), early and late P300 amplitudes and latencies during study and recognition and the amplitude difference between study phase ERPs according to subsequent recognition. (2), Capacity of short-term memory was measured in an auditoryverbal memory span task (forward and backward) and in a visual supra-span test. (3), Speed of memory search (Sternberg) was assessed for numbers and for familiar and unfamiliar faces and objects. Canonical correlation analysis of the variable groups showed that ERPs related to memory span only. This was due to the correlation of - 0 . 4 4 between the backward auditory-verbal span and the late P300 latency during recognition to faces judged as new. Thus, the relationship between individual STM capacity and P300 latency may be found also within subject groups that are homogeneous in respect to age and intelligence and it appears to be attributable to relatively specific processing aspects.