Mucha R F, Weiss R V, Mutz G
Institute of Medical Psychology and Behavioral Neurobiology, Eberhard-Karls-University Tübingen, Germany.
Physiol Behav. 1997 Feb;61(2):293-300. doi: 10.1016/s0031-9384(96)00359-9.
The present report systematically examined a means to electronically detect the erect position in the human in the natural setting. The detector was based on pressure changes in a glycerin filled tube attached to a subject's leg, and it unobtrusively and continuously measured the relative vertical distance between the hip and leg. Initial experiments established the reliability of the sensor system as a function of 1. different sizes of the tubing, 2. different amounts of air in the glycerin and 3. different ambient temperatures (6 degrees-32 degrees C). Then, in a laboratory study of normal adults, the detector was seen to discriminate sitting from standing and (when activity data were included) these two behaviors, in turn, from walking. The detector also accounted for significant differences in HR seen in the standing, as opposed to the sitting, position. In addition, when subjects carried the detector during their daily activities and provided information about their activities using an experience sampling procedure, sitting was discriminated from standing and walking with acceptable diagnostic characteristics. Thus, sitting was detected with a sensitivity of 86.1% (correct detection of all occasions when sitting actually occurred). a positive predictive value of 92.6% (occasions that the detector was right when it indicated sitting), and a negative predictive value of 80.7% (occasions that the detector was right when it indicated sitting). Finally, we demonstrated in two additional ways the direct benefit of our detector in behavioral studies in the natural environment. First, with the detector, we could confirm that a subject had performed simple activities and errands while not under close supervision. Second, cigarette smoking in the natural environment was shown to increase HR, but only when the subjects were sitting. It was concluded that our detector can be effectively applied to the identification of the sitting vs. the erect position in humans in the natural setting, and that this information may be necessary to interpret behavioral and physiological effects seen in such subjects.
本报告系统地研究了一种在自然环境中以电子方式检测人体直立姿势的方法。该检测器基于连接在受试者腿部的充满甘油的管子中的压力变化，它能在不引人注意的情况下持续测量臀部和腿部之间的相对垂直距离。初步实验确定了传感器系统的可靠性与以下因素的关系：1. 不同尺寸的管子；2. 甘油中不同量的空气；3. 不同的环境温度（6摄氏度至32摄氏度）。然后，在一项针对正常成年人的实验室研究中，该检测器能够区分坐姿和站姿，并且（当纳入活动数据时）能够将这两种行为与行走区分开来。该检测器还解释了站立姿势与坐姿相比，心率存在的显著差异。此外，当受试者在日常活动中携带该检测器，并使用经验抽样程序提供有关其活动的信息时，坐姿能够与站姿和行走区分开来，且具有可接受的诊断特征。因此，检测到坐姿的灵敏度为86.1%（正确检测到所有实际发生坐姿的情况），阳性预测值为92.6%（检测器指示坐姿时判断正确的情况），阴性预测值为80.7%（检测器指示非坐姿时判断正确的情况）。最后，我们通过另外两种方式证明了我们的检测器在自然环境中的行为研究中的直接益处。第一，使用该检测器，我们可以确认受试者在没有密切监督的情况下进行了简单的活动和差事。第二，研究表明，在自然环境中吸烟会使心率增加，但仅在受试者坐着时才会如此。研究得出结论，我们的检测器可以有效地应用于在自然环境中识别人体的坐姿与直立姿势，并且这些信息可能对于解释在此类受试者中观察到的行为和生理效应是必要的。
