Psychophysical Measurement Methods

  The picture shows a forearm on which electrodes have been attached Copyright: © Mario Irrmischer  

Electrophysiology deals with methods of measuring the activities and reactions of the human body. The effect of external influences on the human being can be made visible by electrophysiology, for example by using sensors to record the change in physical variables such as the heart rate. The result enables conclusions to be drawn about stress and human well-being.

At the IAW – Institut für Arbeitswissenschaft (Institute of Industrial Engineering and Ergonomics), we use a variety of measurement methods. Electromyography (EMG) and electrocardiography (ECG) are particularly suitable for investigating stress and well-being.

The recording of muscle activities by EMG is usually carried out in the context of investigations into work design. In many cases, the question arises as to how workplaces and jobs can be changed in order to prevent musculoskeletal disorders. An important basis for changes in workplaces and jobs are the reactions of the human body while carrying out the job. Using EMG, these reactions can be made visible and used as a basis for downstream decisions on optimizing workplaces. EMG can also be used to analyze a person's walking patterns or to compare lifting activities on the basis of quantitative stress data. In addition, the design of products such as head-mounted displays (HMD) is also possible, since, for example, the strain on the neck muscles caused by the weight of the HMD can be quantified using EMG.

An ECG is familiar as a form of stress analysis in a medical context and is suitable for examining human cardiac activity. In addition to physical stress, which is the focus of the stress ECG, changes in cardiac activity can also be caused by other influences, such as stress or travel sickness. Further quantitative analysis of the ECG data to determine heart rate variability (HRV) is warranted. Indeed, an ECG can be used for a wide variety of issues and its results can be incorporated into product development. An example of this is the objective recording of travel sickness based on HRV, which allows conclusions to be drawn about the design of motor vehicles and their chassis or autonomous driving programs.

Electrodermatography (EDG) uses sensors, e.g. on the fingers, to measure the skin conductance response (galvanic skin response), which varies due to changes in the activity of the sweat glands. Primarily, the activity of the sweat glands serves the thermoregulation of the human body. This is to be distinguished from the so-called emotional sweating, which occurs, for example, under psychological stress, especially on the hands and feet. The EDG is used for the objective recording of mental stress, for example, in the context of the assessing how difficult a job is.

Since an important part of the information intake takes place via the optic system, it is logical to record the reactions of the optic system when examining stress. With the help of electrooculography (EOG), electrodes placed above and below as well as next to the eye are used to record blinks and changes in the position of the eyes.