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The Relation between Observers' Psychophysiological Conditions and Human Errors during Monitoring Task
Abstract
In this research, we investigated the relation between observers' psychophysiological conditions and human errors made in the task of monitoring electrocardiogram (ECG) wave pattern changes. The number of errors and fingertip volume pulse waves were recorded during the task. Chaos analysis was applied to the fingertip volume pulse waves to calculate the largest Lyapunov exponents. The number of diagnostic errors of judgment and operation errors was treated as human errors. We found significant negative correlation between the largest Lyapunov exponents and human errors. The results showed that when the largest Lyapunov exponents were low, the observers made mistakes.
... For all the experiments, we observed that higher error rates corresponded to lower LLEs, as shown in Figure 16. e line chart and bar chart represent the LLEs and the error rates, respectively [25]. ...
This article is a comprehensive review of recent studies of the authors on the indication of mental health from biological information contained in pulse waves. A series of studies discovered that the largest Lyapunov exponent (LLE) of the attractor, which is constructed for the time series data from pulse waves, can provide as an effective indicator of mental health. A low level of LLE indicates insufficiency of external adaptability, which is characteristic of dementia and depression sufferers. On the contrary, a continuous high level of LLE indicates excessive external adaptability, and people in this condition tend to resort to violence. With this discovery, real-time display of the LLE, combined with other physiological indexes such as the autonomic nerve balance (ANB), sample entropy, and vascular age, as a reference, can enable people to conduct self-check of mental status. To this end, software development was performed in order to enable users to conduct pulse wave measurement anywhere at any time and display the analytical results in real time during the measurement.
... The Lyapunov exponent is a property of chaotic systems that expresses the attractor and represents the "divergence" of the attractor trajectory. We focused on the Lyapunov exponent, which had not been quantitatively evaluated as an index of psychological changes in humans, and investigated its relationship with dementia and communication skill (an ADL index) in aged persons [1], its relationship with error rate at work [8], its relationship with diurnal changes and indices of cumulative fatigue in employees [5]- [7], and the time series fluctuations in divergence in 0-to 5-year-old children and the effect of parental affection towards the children [9]. ...
We applied nonlinear and chaos analysis to fingertip pulse wave data. The largest Lyapunov exponent, a measure of the "divergence" of the trajectory of the attractor in phase space, was found to be a useful index of mental health in humans, particularly for the early detection of dementia and depressive psychosis, and for monitoring mental changes in healthy persons. Most of the methods used for assessing mental health are subjective. A few of existing objective methods, such as those using EEG and ECG, for example, are not simple to use and expansive. Therefore, we developed an easy-to-use economical device, a PC mouse with an integrated sensor for measuring the pulse waves, and its required software, to make the measurements. After about 1 min of measurement, the Lyapunov exponent is calculated and displayed as a graph on the PC. An advantage of this system is that the measurements can be made very easily, and hence mental health can be assessed during operating a PC using the pulse wave mouse. Moreover, the measured data can be saved according to the time and date, so diurnal changes and changes over longer time periods can be monitored as a time series and history. At the time the pulse waves are measured, we ask the subject about his or her physical health and mood, and use their responses, along with the Lyapunov exponents, as factors causing variation in the divergence. The changes in the Lyapunov exponent are displayed on the PC as constellation graphs, which we developed to facilitate simpler self-diagnosis and problem resolution.
... In chaotic datasets, attractor plots and 'divergence' of attractor trajectories are characterized by Lyapunov exponents. Previously, we focused on the Lyapunov exponent of pulse waves in research targeting persons of various ages and in various situations1234. Our results showed that to maintain mental health, it is important that there is harmony with the appropriate functioning of the sympathetic nervous system, which is associated with qualities such as the ability to interact with the external environment and society, flexibility, spontaneity, and cooperation. We also learned that the values representative of such harmony were associated with the maximum Lyapunov exponent (MLE) obtained from nonlinear analysis [5,6]. ...
Previously, we demonstrated that simple, low-cost measurement of an individual's mental health is possible using nonlinear analysis of pulse waves. Here we introduce a trial system that records and assesses the relationship between mental health and lifestyle habits. Our goal was to develop a system that allows individuals to decide which steps to take for recovery when they develop worrying mental health symptoms, by making comparisons to their past lifestyle habits. This system also allows records of multiple individuals to be entered into a database and analyzed. Such analysis should allow for the creation of indicators for general levels of mental health that may require intervention, as well as the creation of more concrete, practical advice to aid recovery when worrying symptoms appear.
... The Lyapunov exponent is a property of chaotic systems that expresses the attractor and represents the " divergence " of the attractor trajectory. We focused on the Lyapunov exponent, which has not previously been evaluated quantitatively as an index of psychological change in humans, and investigated its relationships to dementia and communication skills (an ADL index) in aged persons [1], its relationship to error rate at work [8], its relationship to diurnal changes and indices of cumulative fatigue in employees [5]–[7], and time series fluctuations in divergence in 0-to 5-year-old children, as well as the effects of parental affection toward children [9]. It became clear that suitable functioning and harmony of the sympathetic nerves, which are related to adaptability to the external environment and to society, as well as to flexibility, spontaneity, and cooperativeness of the mind, are important for humans to live in a mentally healthy state. ...
We conducted a nonlinear analysis of fingertip pulse waves and found that the Lyapunov exponent referencing the “divergence” of chaotic attractor trajectory of fingertip pulse waves is an effective method for determining mental health in humans. In particular, we showed that this method is very effective for the early detection of dementia and depression, as well as in the detection of mental changes in healthy persons. In contrast, current measurement methods to determine mental health are subjective in most cases and are neither objective nor simple enough with respect to time and cost. The development of an apparatus allowing easy measurement for many users is therefore necessary. We illustrate the possibility of mental health self-checks using pulse wave divergence based on a series of examples in previous studies. In addition, we developed software to express the fluctuation of the Lyapunov exponent using time series data from multiple measurements. If changes in mental status can be assessed by studying the fluctuation factor of the Lyapunov exponent, we will be closer to effectively evaluating and controlling mental health problems.
... INCE it was discovered that a finger plethysmogram (FPG) shows chaotic fluctuations, several researchers have attempted to assess human psychophysiological states using a chaos analysis to the signals the organism emits [1][4] 1 . The chaos analysis is used to evaluate the chaotic fluctuation, which is expressed by the largest Lyapunov exponents (LLEs). ...
We investigated the largest Lyapunov exponents (LLEs) of finger plethysmogram (FPG) and heart rate (HR) under anxiety, fear and relief states and compared each measured LLEs with the HR. We devised a task in which the participants experienced the emotions of anxiety, fear, and relief. FPG and HR were recorded during the task, and chaos analysis was applied to FPG to calculate the LLEs. Our results showed significant positive correlations between the LLEs of FPG and the degrees of anxiety and fear. In addition, the degree of relief showed a significant negative correlation with the LLEs of FPG. However, no significant correlation was observed between HR and the degrees of three emotions. These results suggest that the LLEs of FPG are a more sensitive psychological index than the HR.
Thus far, attention has been paid to the relation between pain and anxiety, which has been studied. On the other hands, the earlier studies have hinted at the importance of considering mental and physical health from a holistic perspective, while taking into consideration the principles that prescribe the chaotic behavior of living organisms. Therefore, the purpose of this study is to use the respiration and pulse waves to examine the nature of the chaotic connection between biosignals involved in people's mental and physical conditions, particularly those involved in the psychological trait of anxiety under a painful stimulus in this case. The results showed that with the high anxiety group, the extent of the synchronicity between their respiration and pulse waves under a painful stimulus increased, while this decreased for the low anxiety group. In other words, chaos dynamics for living systems are expressed in synchronous phenomena for the LLE for respiration and pulse waves. It also implied that these dynamics are prescribed by trait anxiety under a painful stimulus. This has opened up the possibility that, in the future, the cross-correlation function for LLE in pulse waves and respiration will make contributions to treating and assessing chronic pain in the field of clinical medicine.
Thus far, attention has been paid to phenomena wherein the cardiovascular system and respiratory movement system have worked in coordination with one another, which has been studied. On the other hands, the earlier studies have hinted at the importance of considering mental and physical health from a holistic perspective, while taking into consideration the principles that prescribe the chaotic behavior of living organisms. In other words, this raises the issue: The validity of hypothesizing chaos dynamics as a universal principle for living systems that prescribes the chaotic nature of pulse waves and respiration. Therefore, the purpose of this study is to focus on pulse waves and respiration in order to examine the relationship in the chaotic nature between the two. Consequently, the issue presented above was supported. What this implies is that quantitatively assessing synchronous phenomena for the LLE for pulse waves and respiration used in this study is a more highly valid approach for determining people's mental and physical conditions in the fields of clinical medicine and ergonomics, and therefore it could potentially be applied as a means of substantially supporting the promotion of health.
In this research, the relation between oral reading and readers' psychophysiological conditions was examined in a total of 16 university students (aged between 18 and 24). The students were asked to read an English passage aloud for about three minutes. Fingertip pulse waves were measured for use as biological data before and after reading the passage. The measured values were subjected to chaos analysis and the Lyapunov exponents calculated. It was found that there was significant positive correlation between oral reading and readers' psychophysiological conditions. The results showed that Lyapunov exponents became higher after the readers read the passage orally.
The authors of this chapter measured plethysmography and calculated the Largest Lyapunov Expornent (LLE) using non-linear analysis. They found that the value of LLE was significantly related to the severity of dementia and the communication skill in the ADL index for 144 elderly individuals. The authors developed a mathematical model to analyze the results by studying the information extracted from the plethysmogram data. Furthermore, data were collected when the central nerve was blocked by general anesthesia to evaluate the mathematical model. The pulse wave data indicated that the authors included information from the nucleus of the brain origin. In other words, they obtained conclusive evidence of dementia using the LLE and communication skills. The authors measured pulse waves while elderly individuals had a conversation. They calculated the activation of the sympathetic nerve and the parasympathetic (LF/HF, HF) response simultaneously. LLE that was activated by communication had a low HF, and the HF was high in individuals who were not activated. In other words, an effect of communication was observed in conscious elderly individuals. Communication scientifically indicated the mental activity of elderly individuals.
The purpose of this research is development of the system which can display its mental condition numerically and can check its mental condition by itself.
Offer of the effective information for a life – by this, we discover discovery of the optimal time in case he works, and a better communication condition with their friend – is attained. In order to attain this, GUI intelligible for a user needs development of the engine for analyzing development of a pulse wave sensor and a pulse wave, and to be developed. In an announcement, what was developed by PC or the tablet is introduced as one step of development.
In ambient information systems, not only extracting human behavior with a sensor network but also adaptive autonomous interaction between the environment and humans is an important function. In this paper, we propose a reinforcement learning methodology for acquiring suitable interaction for each person's daily behavior. This time, we used vital sensors to detect and classify a user's condition. In an experiment, we show the feasibility of the proposed methodology.
In ambient information systems, not only extracting human behavior with a sensor network but also adaptive autonomous interaction between the environment and humans is an important function. In this paper, we propose a reinforcement learning methodology for acquiring suitable interaction for each person's daily behavior. This time, we used vital sensors to detect and classify a user's condition. In an experiment, we show the feasibility of the proposed methodology.
In order to measure the mental activity, people measured the subject's
oral consultation data, cardiac beats, a pulse wave, brain waves, an
electromyogram, action patterns, and so on, together with analyzed data.
Regarding the vital signs are the information on a complexity system, we
were treating a slight change of vital signs as an error. However, very
important information was included in this error. The degree of mental
activity which is the information on the complexity system was not able
to be solved by the conventional method. In this paper, nonlinear
analysis of the pulse wave of a fingertip was conducted, and the
fluctuation value was computed. Furthermore, the simulation of a
mathematical model and the experiment of anesthesia proved that the
value had the information on a central system. The apparatus which can
measure the degree of mental activity was developed using this.
To examine human health, we need to check changes over time in the states of various vital signs such as blood pressure, body temperature, and blood glucose level. As long as the human body is alive, vital signs are the values that keep delicately fluctuating within a certain range due to homeostasis, and it is possible to predict signs of diseases when vital signs fluctuate widely. Therefore, it is necessary to check the variations in the time series. In this research, we developed a system that can display time-series variations of vital signs, including delicate changes in values, on a semicircular graph. As an example, we show the fluctuation of the Lyapunov exponent, which relates to mental health in sympathetic nerves, and which the author has been researching, in a time-series constellation graph.
This study investigated the relations between the largest Lyapunov exponents of the finger plethysmogram and pulse indices. First, we made a sine wave that had various pulse intervals and examined the relations using a simulation. Consequently, the largest Lyapunov exponents decreased with the standard deviation of the pulse interval. Next, we carried out two experiments and reexamined the relations using actual measurements of finger plethysmogram recorded during rest and during two mental tasks. We found a significant positive correlation between the standard deviation of the pulse intervals of the finger plethysmogram and the largest Lyapunov exponent, and the correlation coefficient was the highest of pulse indices in two experiments. From these results, we concluded that the largest Lyapunov exponents of the finger plethysmogram are greatly affected by the standard deviation of pulse intervals may be a more reasonable measurement than the largest Lyapunov exponents of the finger plethysmogram.
We measured the fingertip pulse waves of some of the elderly living in a care house (a welfare facility for the elderly) four times a day over two days to investigate their mental condition. We analyzed the chaotic information produced by the finger pulse waves using a nonlinear analysis method. The results of our research are as follows: 1) The Largest Lyapunov Exponent (LLE), which synchronizes to mental revitalization, rose when the care house residents felt happy. 2) After moderate movement (a stroll, etc.), the LLE was high. 3) The LLE did not rise when a regular action was carried out non‐vigorously to kill time. 4) When residents made contact (a phone call or letter, etc.) with a family member, the LLE was high. 5) The LLE of long‐term residents was high. 6) The majority of residents with high LLE moved into the care house in their early seventies. 7) The LLE of short‐term residents was low and their sympathetic nerves were high. 8) There was no relativity between the LLE and present age of the care house residents. On this basis, the authors propose that fuller support of care house residents is crucial for the objective ascertainment of their mental condition.
The fingertip pulse waves of a number of staff working in a daycare center for the elderly and a special nursing home for the elderly were measured several times throughout the day for a period of one or two days, and the chaotic information gained was analyzed using a non linear analysis method. As a result, a relation between the staff’s length of career and the change of Largest Lyapunov Exponent (LLE) of the fingertip pulse waves that synchronized with the mental revitalization degrees and the tension of the sympathetic nerve was evident. The LLE of the staff with short careers dramatically changed and also took a long time to settle down again. In addition, staff LLE changed greatly after sessions of bathing assistance and watching residents with dementia. LLE measurements showed drops in some staff after a period of rest, but this was not the case for other staff. It can be concluded that the LLE is related to the length of the staff member’s career and what is actually done during working hours and rest periods. A high level of sympathetic nerve was seen in almost all of the care workers. On this basis, the authors propose that improvements are needed in the content of the care work.
We measured the pulse waves of 196 mentally ill patients and 113 healthy students. Using heartbeat changes, we calculated the values of their sympathetic nerves, parasympathetic nerves, and autonomic nerve balance. In addition, we calculated the largest Lyapunov exponents (LLE) by non‐linear analysis of plethysmograms. Values were analyzed by group. The results revealed a significant relationship between LLE and the autonomic nerve balance. The sympathetic nerve values in the patient group were significantly higher than those in the student group, whereas the LLE values were significantly lower. Furthermore, we illustrated the dynamic change in the results for single participants over several testing times. The measurement of pulse waves is easy and economical and does not put a strain on the subject. Additionally, these values can provide information that is more accurate than medical examination obtained from an interview. Our study contributed to the existing methodology in this field, and future data collection and measurement will be carried out. We hope that our study will be useful for neurologists and psychotherapists in their detection and treatment of mental illness.
We measured plethysmograms and calculated Largest Lyapunov Expornent (LLE ) with nonlinear analysis method. We found the value of LLE had significant relation to dementia degree and the communication skill of the ADL index for the measurement of 144 elderly people. We made a mathematical model to discuss the obtained experimental results by studying simulated what kind of information was able to extract from the plethysmograms data. Furthermore, we performed the measurement when we blocked the central nerve by general anesthesia to inspect the mathematical model. As a result, the data of the pulse wave elucidated that we included information of nucleus of the brain origin. In other words we got the conclusive evidence of having meaningful relation to dementia and LLE and a communication skill. We had an old man communicate in friendly care manager to an elderly people from these facts and measured the pulse wave at the same time. We calculated a sympathetic nerve, the value of the parasympathetic (LF/HF, HF) at the same time. As a result, the person whom LLE activated by communication had a low HF, and the person who was not activated understood that HF was in a high state. In other words an effect of the communication was accepted when an elderly people awoke. By this study, the communication was able to prove that we helped the mental activation of the elderly people scientifically.
The fingertip pulse waves of some of the elderly living in welfare facilities and a number of staff working in a daycare center for the elderly and a special nursing home for the elderly were measured several times throughout the day for a period of one or two days, and the chaotic information gained was analyzed using a non linear analysis method. As a result, differences were found in the value of the Lyapunov exponent in the fingertip pulse waves as information regarding vital signs reflecting the level of mental revitalization and the value of autonomic balance. The care workers were also asked to fill out a questionnaire. Information regarding the fingertip pulse waves of the elderly and the care workers is a basis for considering the improvement of the quality of care. Accordingly, the authors propose improvements in the content of the care work.
Constellation graphs for time-series data are very effective tool for displaying a physio-psychological index. In this study, we recorded fingertip pulse waves of elderly subjects, carried out chaos analysis on the plethys- mogram data thus obtained, and examined their relationship with dementia. We discovered the Lyapunov exponent of the time series had a clear relationship with the severity of dementia and the communication skill of the elderly sub- jects. We could clearly demonstrate a relationship between dementia and the Lyapunov exponents using constellation graphs of the time series data.
Chaos theory was applied to analysis of the time series of plethysmograms under various human physio-psychological conditions.
It found that the largest Lyapunov exponent could be used to characterize physio-psychological status. A visual representation
method based on constellation graphs was developed to indexing temporal changes in the largest Lyapunov exponent. Changes
of constellation angles were found to clearly characterizing variations of physio-psychological status in a series of experiments.
The presence of deterministic chaos has been clarified experimentally in the time series of pulsation of capillary vessels [Tsuda et al., 1992]. In this paper, first we reconfirmed the nonlinearity of the time series of pulsation of capillary vessels with surrogate data testing. Second, we investigated the characteristics of chaos of capillary data on normal subjects in different states of the autonomic nervous system and on psychiatric patients. As a result the chaotic fluctuations decreased for the state of sympathetic dominance of normal subjects On the contrary, the chaotic fluctuations increased for the state of parasympathetic predominance of normal subjects. We also found that the chaotic fluctuations decreased in the symptomatic phase of psychiatric patients. Interpretation of this fact is as follows. Psychiatric patients in symptomatic phase are in a condition of poor flexibility of emotion and motivated behavior in the limbic system. This condition affects the regulation of the autonomic nervous system in the hypothalamus. So it is easy to fall into the imbalance of the autonomic nervous system even with slight stress. Furthermore, in the attractor of capillary chaos we found two parts that showed the role of origin of stimulation of the sympathetic nervous system and that of stimulation of the parasympathetic nervous system, respectively. The geometrical change of topology was caused by the interplay of two parts. From our study we concluded that chaos of pulsation in capillary vessels reflected mental conditions through the autonomic nervous system.
The presence of deterministic chaos has been clarified experimentally in the time series of pulsation of capillary vessels [Tsuda et al., 1992]. In this paper, first we reconfirmed the nonlinearity of the time series of pulsation of capillary vessels with surrogate data testing. Second, we investigated the characteristics of chaos of capillary data on normal subjects in different states of the autonomic nervous system and on psychiatric patients. As a result, the chaotic fluctuations decreased for the state of sympathetic dominance of normal subjects. On the contrary, the chaotic fluctuations increased for the state of parasympathetic predominance of normal subjects. We also found that the chaotic fluctuations decreased in the symptomatic phase of psychiatric patients. Interpretation of this fact is as follows.
Psychiatric patients in symptomatic phase are in a condition of poor flexibility of emotion and motivated behavior in the limbic system. This condition affects the regulation of the autonomic nervous system in the hypothalamus. So it is easy to fall into the imbalance of the autonomic nervous system even with slight stress. Furthermore, in the attractor of capillary chaos we found two parts that showed the role of origin of stimulation of the sympathetic nervous system and that of stimulation of the parasympathetic nervous system, respectively. The geometrical change of topology was caused by the interplay of two parts. From our study we concluded that chaos of pulsation in capillary vessels reflected mental conditions through the autonomic nervous system.
We found a chaotic pulsation in a finger’s capillary vessels in both normal subjects and psychiatric patients, as well as cardiac chaos. A proof of chaos was made by the reconstruction of the dynamics in phase space and the calculation of the Lyapunov exponents. From the aspect of chaotic information processing, we give a measure of the information storage capacity of the observed chaos. We also found a difference in the topology of capillary and cardiac chaos, and a difference in their dependence on the subject’s conditions.
Chaotic time series data are observed routinely in experiments on physical systems and in observations in the field. The authors review developments in the extraction of information of physical importance from such measurements. They discuss methods for (1) separating the signal of physical interest from contamination ("noise reduction"), (2) constructing an appropriate state space or phase space for the data in which the full structure of the strange attractor associated with the chaotic observations is unfolded, (3) evaluating invariant properties of the dynamics such as dimensions, Lyapunov exponents, and topological characteristics, and (4) model making, local and global, for prediction and other goals. They briefly touch on the effects of linearly filtering data before analyzing it as a chaotic time series. Controlling chaotic physical systems and using them to synchronize and possibly communicate between source and receiver is considered. Finally, chaos in space-time systems, that is, the dynamics of fields, is briefly considered. While much is now known about the analysis of observed temporal chaos, spatio-temporal chaotic systems pose new challenges. The emphasis throughout the review is on the tools one now has for the realistic study of measured data in laboratory and field settings. It is the goal of this review to bring these tools into general use among physicists who study classical and semiclassical systems. Much of the progress in studying chaotic systems has rested on computational tools with some underlying rigorous mathematics. Heuristic and intuitive analysis tools guided by this mathematics and realizable on existing computers constitute the core of this review.
The exponential divergence or convergence of nearby trajectories (Liapunov exponents) is conceptually the most basic indicator of deterministic chaos. A new method is proposed to determine the spectrum of several Liapunov exponents (including positive, zero, and even negative ones) from the observed time series of a single variable. The method has been applied to various known model systems and also to the Rayleigh-Benard experiment, and the dependence of the Liapunov exponents on the Rayleigh number has been elucidated.
Chaotic Voice Analysis and Model of Cerebral Dynamics
- K Shiomi
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Development and Application of a System for Measuring the Error of Judgment and Operation in Monitoring Task
- A Imanishi
- M Oyama
Application of chaos in clinical case
- T Tahara
Tahara T., "Application of chaos in clinical case," J Society of
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Time Course of Errors and Lyapunov Exponents by Block for Six Patients Condtion
- Fig
Fig.8. Time Course of Errors and Lyapunov Exponents by Block
for Six Patients Condtion.
- Monitoring Task
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253-256, 2005.
Development and Application of a System for Measuring the Error of Judgment and Operation in Fig.9. Time Course of Errors and Lyapunov Exponents by Block for Nine Patients Condtion
- A Imanishi
- M Oyama
Imanishi A. and Oyama M., "Development and Application of a
System for Measuring the Error of Judgment and Operation in
Fig.9. Time Course of Errors and Lyapunov Exponents by Block
for Nine Patients Condtion.