Psychophysiological Mesures in Stress Assessment and Biofeedback

Various psychophysiological measures are used as clues to capture the dynamically changing state of the body, which is always in flux. In psychosomatic medical evaluation, treatment, and research, the following psychophysiological indicators are used as easy-to-capture measures of dynamically changing states:

These indicators change sensitively not only with physical but also with psychological and behavioral states (mind-body correlation). Specifically, they are used in psychosomatic medicine for Psychophsiological Stress Profiles and biofeedback.

Significance of Psychophysiological Measurement in Psychosomatic Medicine

In psychosomatic disorders or functional somatic syndromes, the pathology may not be adequately captured by conventional medical examinations alone.

For example, in “functional dyspepsia (FD)”, no abnormalities are found in gastroscopy, but symptoms such as epigastric pain due to abnormalities in gastric motility lead to a decrease in quality of life. In capturing such pathologies, methods such as gastric fluoroscopy to observe gastric motility are available. Another approach involves evaluating the relationship between the functioning of the autonomic nervous system that governs gastric motility and psychological states.

Psychophysiological indicators “visualize” such invisible functional changes in real time. By “visualizing” and “objectifying,” it becomes easier to capture functional pathologies, understand the mind-body correlation related to stress, and lead to insights that contribute to psychosomatic medical approaches.

List of Psychophysiological Measures

Psychophysiological MesuresOverview
1) Electromyography (EMG)
<Observing muscle tension/relaxation>
In today’s stressful lifestyles, sustained muscle tension contributes to problems such as shoulder stiffness, headaches, lower back pain, and chronic pain. This indicator captures the degree of muscle tension and relaxation involved in such pathologies.
2) Skin Conductance Level (SCL)
<Observing emotional sweating>
Among sweating, palmar sweating is central and responds to emotional changes. Lie detectors utilize this and are sensitive to psychological agitation. It captures the level of arousal, psychological agitation/stability, tension/relaxation, etc.
3) Skin Temperature (TEMP)  
<Observing skin temperature>
Skin temperature is constantly changing due to factors such as peripheral vasodilation and constriction. Stress causes peripheral blood vessels to constrict, leading to poor circulation and decreased skin temperature. Skin temperature captures changes in peripheral circulation according to such situations and is also important as an indicator of relaxation, such as in autogenic training.
4) Blood Volume Pulse (BVP)  
<Observing peripheral blood vessel constriction/dilation>
With fingertip plethysmography, it directly captures changes in peripheral blood vessels along with skin temperature. Also, it can determine heart rate from pulse waves, allowing heart rate to be captured without electrocardiography.
5) Respiration (RESP)  
<Observing breathing pattern/depth/speed>
Respiration is key to various bodily regulation methods and serves as a point of contact between consciousness and unconsciousness. By capturing respiration, various states of mind and body can be inferred.
6) Electrocardiography (EKG)  
<Observing heart function>  
The heart is the source of bodily activity and rhythm. Its function changes significantly not only with physical but also with psychological states. Biofeedback mainly captures heart rate and heart rate variability. Heart rate is the source of biological rhythms and is also a comprehensive indicator of autonomic nervous system tension/relaxation, as is often described as “palpitating” when stressed.
7) Heart Rate Variability (HRV)  
<Indicator of autonomic nervous system function>
Heart rate variability is one of the most studied indicators as it objectively captures autonomic nervous system function. From heart rate variability, you can evaluate the degree of autonomic nervous system tension, flexibility of adaptation, and balance between sympathetic and parasympathetic nervous systems.

(Kanbara K, LABs Psychosomatic Medicine,, July 2022)