Social stress and performance in human-machine interaction: a neglected research field.

Given the increasing capabilities of highly automated systems, the article argues for a need to address the issue of social stress in human-machine interaction. It suggests a classification system of subordinate concepts found in the research literature under the heading of social stress. A review of the literature revealed a paucity of studies examining the effects of social stressors on performance. In particular, the review showed a shortage of experimental lab-based work, needed to establish clear cause-effect relationships. The article examined the suitability of different social stressors for lab-based research, not only when humans are the source of stress but also in so-called hybrid teams where social stress is caused by machine agents. The review shows that a closer link is needed between the separate literature on social stress and automation. Finally, three mechanisms are proposed that may predict how social stress may affect performance: 'blank-out'-mechanism, 'rumination'-mechanism, and 'increased-motivation'-mechanism. Practitioner summary: Theories of ergonomics and human factors may benefit from better integration of research and theoretical work in the domain of social stress. This is due to the increasing capabilities of machines to induce social stress. Abbreviations: HMI: human-machine interaction; TSST: trier social stress test.

Nutrition with 'light and water'? In strict isolation for 10 days without food - a critical case study.

BACKGROUND: In her book 'Living on Light', Jasmuheen tries to animate people worldwide to follow her drastic nutrition rules in order to boost their quality of life. Several deaths have been reported as a fatal consequence. A doctor of chemistry who believably claimed to have been 'living on light' for 2 years, except for the daily intake of up to 1.5 l of fluid containing no or almost no calories was interested in a scientific study on this phenomenon. PARTICIPANT AND METHODS: The 54-year-old man was subjected to a rigorous 10-day isolation study with complete absence of nutrition. During the study he obtained an unlimited amount of tea and mineral water but had no caloric intake. Parameters to monitor his metabolic and psychological state and vital parameters were measured regularly and the safety of the individual was ensured throughout the study. The subject agreed on these terms and the study was approved by the local ethics committee. RESULTS: The most important observations were a permanent urinary excretion of ketones, up to a 3-fold increase in free fatty acid plasma levels, a mean weight loss of 0.26 kg/d, and an initially secondary hyperaldosteronism. Additionally, his ability to exercise was reduced. The subject remained psychologically stable and testing did not reveal any relevant changes. CONCLUSION: The results refute the claim and indicate a phase-II fasting state.

Decision-making dysregulation in first-episode schizophrenia.

Studies with chronic schizophrenia patients have demonstrated that patients fluctuate between rigid and unpredictable responses in decision-making situations, a phenomenon which has been called dysregulation. The aim of this study was to investigate whether schizophrenia patients already display dysregulated behavior at the beginning of their illness. Thirty-two first-episode schizophrenia or schizophreniform patients and 30 healthy controls performed the two-choice prediction task. The decision-making behavior of first-episode patients was shown to be characterized by a high degree of dysregulation accompanied by low metric entropy and a tendency towards increased mutual information. These results indicate that behavioral abnormalities during the two-choice prediction task are already present during the early stages of the illness.

Comprehensive rehabilitation in chronic heart failure--better psycho-emotional status related to quality of life, brain natriuretic peptide concentrations, and clinical severity of disease.

PURPOSE: To evaluate the effects of a comprehensive outpatient rehabilitation program in chronic heart failure (CHF) on quality of life (QoL) in relation to emotional status and clinical severity of disease. PATIENTS AND METHODS: 25 patients with CHF were included in the 12-week comprehensive rehabilitation program. Initially, and at the end of the program, patients underwent graded cardio-pulmonary exercise testing, echocardiography, and determination of brain natriuretic peptide (BNP) concentration. In addition, they were assessed using: The Minnesota Living with Health Failure Questionnaire [MLHFQ]) for disease Specific QoL, the Hospital Anxiety and Depression Scale [HADS], and the State-Trait Anger Expression Inventory [STAXI]). RESULTS: After 12 weeks of rehabilitation improvements in NYHA class, left ventricular ejection fraction (LVEF), and peak oxygen consumption were found, while mean BNP concentrations did not change. Disease specific QoL demonstrated improvements in physical component and the total score. Relative improvement of psycho-emotional scores correlated positively with relative improvement of disease specific QoL. In patients with LVEF > or =30% at baseline, changes in BNP concentration were positively associated with both anxiety and state anger, and with the emotional component score of MLHFQ. CONCLUSION: Improvements in disease-specific QoL were closely associated to improvements of psycho-emotional status and clinical severity of CHF.