JPH1119075A - Mental stress judging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To objectively and accurately judge the presence of a steady mental stress by measuring a brain wave of a subject using a simple measuring device. SOLUTION: While a temporary stress is applied by a task/rest presenting device 1, a brain wave data is measured by a simple brain wave data measuring device 2 with an electrode mounted on the forehead of the subject and a frequency power calculating circuit 13 of a brain data signal processing circuit 3 discards a noise data such as myoelectric signal or the like attributed to winking to calculate a power spectrum in terms of frequency band. A power spectrum is added per frequency under a task and a rest with quietly closed of eyes by a frequency power addition circuit 14 and an αwave power normalization circuit 15 calculates a ratio between the power spectrum in all frequency bands of the brain wave and the power spectrum in the frequency band of αwave separately under the task and the rest. A mental stress judging circuit 4 compares the ratio obtained under the task and the ratio under the rest to judge the presence of a mental stress.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mental stress determination device for determining mental stress as a constant stress of a person.

[0002]

2. Description of the Related Art Conventionally, there is a stress level measuring apparatus for measuring a stress level of a person by measuring a fluctuation state of pulse data by a microcomputer. This is because, as shown in FIG. 12, a pulse wave detector 7 for detecting a subject's pulse wave is connected to a pulse counter 8, and the pulse counter 8
Are connected to the microcomputer 9. Then, as shown in FIG. 13, the pulse wave data 31 detected by the pulse wave detector 7 is converted into a shaped pulse 32 by the pulse counter 8, and the pulse data is counted. By monitoring at step 9, the level of stress is measured. A similar one is described in JP-A-4-180730.

[0003]

In recent years, people have been subjected to various stresses at work or in daily life. In particular, due to rapid OA (office automation) and FA (factory automation), VDT (video display terminal) work and monitoring work have increased, and mental stress caused by these work has become a factor of overwork and human error. I have. In order to prevent this, it is important to evaluate and determine mental stress (also called techno stress).

[0004] However, the conventional stress level measuring device is configured to use only information on the rise and fall of the pulse, so that the reliability of the stress level measurement is low and only the temporary stress at the time of measurement can be measured. Also,
When a phenomenon such as an arrhythmia occurs in the electrocardiogram signal, the section cannot be analyzed. Although arrhythmias usually occur even in healthy individuals, many subjects have arrhythmias in mental stress. When an unanalyzable section due to arrhythmia frequently occurs, there is a problem that determination itself becomes impossible.

[0005] Then, there is an attempt to determine the mental stress state by measuring the electroencephalogram of the subject by utilizing the high correlation between mental stress and electroencephalogram. It measures brain waves of a subject in a resting state for several minutes, performs frequency analysis, and determines mental stress,
Only temporary stress at the time of measurement can be measured, and the reliability of the steady-state stress level measurement accumulated over a long period of time is low. Also, when measuring brain waves, it is necessary to attach a large number of electrodes to the scalp by dividing the hair
This has caused annoyance in the measurement of EEG.

As described above, at present, it can be said that a technique for simply measuring the amount of sensation of mental stress and for objectively and quantitatively evaluating it with high reliability has not been established. The present invention has been made in view of the above-described conventional problems, and has as its object to provide a mental stress determination device that objectively accurately determines mental stress as stationary stress by a simple measurement method.

[0007]

Therefore, the present invention provides a task presenting means for temporarily applying stress to a subject, a simple electroencephalogram data measuring means for measuring electroencephalogram data of the subject,
A brain wave that performs frequency analysis of the brain wave data measured by the brain wave data simple measuring means and calculates a normalized α wave power which is a ratio of a power spectrum corresponding to the entire frequency band of the brain wave to a power spectrum of a frequency band corresponding to the α wave. It is assumed that the apparatus has a data signal processing unit and a mental stress determination unit that determines a mental stress based on the normalized α-wave power calculated by the brain wave data signal processing unit.

[0008] It is preferable that the task presenting means includes a timer, and the timer presents the time so that the subject alternately performs the task and the rest for a predetermined time. Also,
The electroencephalogram data simple measurement means may collect electroencephalogram data from the forehead, and the electroencephalogram data signal processing means may have non-target signal removal means for detecting and removing noise signals such as blinks.

The electroencephalogram data signal processing means includes a frequency power calculation means for calculating a frequency power spectrum for each frequency band from the electroencephalogram data detected by the electroencephalogram data simple measurement means, and a frequency power spectrum calculated by the frequency power calculation means. Frequency power adding means for adding the spectrum in the task state and the rest state for each frequency band, and the power of the α wave with respect to the power in the entire frequency band in each of the task state and the rest state added by the frequency power adding means. An α-wave power normalizing circuit for calculating a normalized α-wave power as a ratio, wherein the mental stress determining means includes a normalized α-wave power in the task state and a normalized α in the rest state.
Mental stress can also be determined based on the ratio of wave power.

Further, the electroencephalogram data signal processing means includes a frequency power calculating means for calculating a frequency power spectrum for each frequency band from the electroencephalogram data detected by the electroencephalogram data simple measuring means, and a frequency power spectrum calculated by the frequency power calculating means. In the task state and the rest state, the frequency power addition means for adding each frequency band, and in each of the task state and the rest state added by the frequency power addition means, the ratio of the power of the α wave to the power of the entire frequency band. It has an α-wave power normalization circuit that calculates a certain normalized α-wave power, and the mental stress determination unit calculates the ratio of the normalized α-wave power of the task state measured last time and the normalized α-wave power of the rest state. , Based on the change in the ratio of the normalized α-wave power in the task state and the normalized α-wave power in the rest state It is also possible to determine the down barrel stress.

[0011]

[Effect] Originally, brain waves have large individual differences in their generation state,
It is difficult to determine steady mental stress from electroencephalogram data measured only once. In the mental stress determination device according to the present invention, by the task presenting means, for example, a task state that imposes a temporary mental work on the subject,
A rest state where no mental work is imposed is set, and a difference between brain wave components in the task state and the rest state is observed to determine the presence or absence of mental stress. In other words, focusing on the fact that the flexibility of the subject for mental work is greatly affected by mental stress as stationary stress, the present invention uses one of the frequency bands of the electroencephalogram as an index indicating the flexibility of the subject for mental work. Is used in the task state and the rest state.

More specifically, brain wave data of a subject is collected by a simple apparatus for measuring brain wave data, input to a brain wave data signal processing means, frequency analysis is performed, and a power spectrum and an α wave corresponding to the entire frequency band of the brain wave are obtained. Calculated normalized α-wave power, which is the ratio of the power spectrum of the frequency band corresponding to
Mental stress determination means determines the presence or absence of steady mental stress based on the normalized α-wave power. Thereby, the sensory mental stress is objectively determined.

Further, when the task presenting means presents a time by a timer so that the task and the rest for a certain time are alternately performed by the timer, a simple task is given to the subject, and the brain wave is given. Data is easily collected.

[0014] Using the above-mentioned simple apparatus for measuring electroencephalogram data,
By collecting the subject's brain wave data from the forehead, the trouble of dividing the hair can be omitted, and the brain wave data can be collected extremely easily. However, as shown in FIG. 14A, in the method of detecting from the normal occipital region 33, the noise signal is rarely mixed into the electroencephalogram data. A pulse-like myoelectric signal 35 such as a blink as shown in FIG.
And other noise signals are likely to be mixed into the brain wave data. For that purpose, an unintended removal means is provided to detect noise signals,
By removing it, brain wave data is simply collected, and mental stress can be determined with high accuracy.

Further, when the electroencephalogram data signal processing means calculates the ratio between the normalized α power in the task state and the normalized α power in the rest state, the mental stress determining means can calculate the ratio when the ratio is small. When there is no mental stress and this ratio is large, it can be determined that there is mental stress. Also, by comparing the ratio of the normalized α-wave power in the task state and the rest state in the previous measurement and the current measurement, it is possible to know the state of change in mental stress.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to examples. FIG. 1 shows the configuration of the first embodiment, and FIG. 2 shows the state of use. FIG. 3 is a diagram showing the timing of giving a task, and FIGS. 4 and 5 are flowcharts for explaining the operation. Here, we focus on the α (alpha) wave in the brain wave, measure and calculate the normalized α wave power with the temporary stress applied, and observe the change with respect to the background steady stress, By removing the electroencephalogram data when a phenomenon such as blinking occurs, a highly accurate determination can be made without interrupting the analysis.

As shown in FIG. 1, the mental stress determination device includes a task / rest presenting device 1 as a task presenting means for temporarily applying stress to a subject, a simple electroencephalogram data measuring device 2 for collecting brain wave data of the subject, A brain wave data signal processing circuit 3 that performs frequency analysis of the collected brain wave data to calculate normalized α-wave power, and a mental stress determination circuit 4 that determines mental stress based on the calculated normalized α-wave power. It is configured.

As shown in FIG. 2, the task / rest presenting device 1 is a device for presenting a task with little body movement to a subject. A task (task) and a rest (rest) for a certain period of time are set by a built-in timer. Is presented to the subject. Specifically, as shown in FIG.
The task is set for about 1 minute, the rest is set for about 2 minutes,
The task and the rest are alternately and repeatedly presented multiple times. The task may be any content as long as mental stress can be applied. For example, as shown in FIG. In addition, the task of writing as many circles 24 as possible is imposed.

As shown in FIG. 2, the electroencephalogram data simple measuring device 2 is attached to the forehead of the subject, and the forehead mounting electrode 11 for collecting electroencephalogram data and the collected electroencephalogram data are sent to the electroencephalogram data signal processing circuit 3. , An electroencephalogram data transfer device 12 that transfers data by wire or wirelessly. Since accurate waveform diagnosis for medical use is not the purpose, mounting of electrodes may be simple, and an electrode is attached to the forehead, and a bee-shaped electrode capable of simple measurement is used.

The electroencephalogram data signal processing circuit 3 analyzes the frequency components of the electroencephalogram data, removes unintended signals such as electroencephalogram data including noise and electroencephalogram data at the boundary between a task and a rest, and separates the signals into frequency bands. A frequency power calculating circuit 13 for calculating a frequency power spectrum, a frequency power adding circuit 14 for dividing the frequency power spectrum for each frequency band separately at the time of the task and at the time of rest, and all frequency bands at the time of the task and at the time of rest. An α-wave power normalizing circuit 15 for calculating a normalized α-wave power which is a ratio of the α-wave power spectrum to the frequency power spectrum of
The output of the wave power normalizing circuit 15 is input to the mental stress determination circuit 4. Here, the electroencephalogram data signal processing circuit 3 and the mental stress determination circuit 4
Is composed of a computer.

Next, the operation will be described. While temporarily applying stress to the subject by the task / rest presentation device 1, the subject's brain wave data collected by the electroencephalogram data attaching electrode 11 is transferred by the brain wave data transfer device 12, and the frequency power calculation circuit of the brain wave data signal processing circuit 3 Input to 13. The frequency power calculation circuit 13 first cuts out the brain wave data for about one second and performs frequency analysis to obtain a frequency power spectrum for each frequency band. Here, the electroencephalogram data in which the frequency spectrum of the frequency band corresponding to the noise such as blinking is included in a predetermined ratio or more is discarded as non-target data.

In the frequency power adding circuit 14, first, the electroencephalogram data corresponding to the boundary time between the task state and the rest state is discarded as unintended data.
Apart from the rest state, the α-wave power normalization circuit 15 that adds each frequency power spectrum for each frequency band has a ratio P (T) between the power spectrum of all frequency bands and the α-wave power spectrum in the task state, and a rest. Ratio P between the power spectrum of all frequency bands and the α-wave power spectrum in the state
(R) is calculated.

In the mental stress determination circuit 14, the ratio P (T) of the power spectrum of all the frequency bands to the α-wave power spectrum in the task state and the ratio of the power spectrum of the entire frequency band to the α-wave power spectrum in the rest state P
A stress level MS, which is a ratio of (R), is calculated, and based on the stress level MS, the presence or absence of a mental stress that is a steady stress is determined.

Next, the flow of the operation in this embodiment will be described.
This will be described in more detail with reference to the flowcharts shown in FIGS. In step 101, the task / rest presenting device 1 presents a task to the subject. In step 102, the subject's brain wave data is measured by the forehead mounting electrode 11 of the simplified brain wave data measurement device 2.

In step 103, the electroencephalogram data transfer device 12 transfers the electroencephalogram data to the electroencephalogram data signal processing circuit 3. In step 104, the EEG data is A / D-converted by the frequency power calculation circuit 13 to 1 kHz.
Sampling is performed as described above, and is sequentially captured. In step 105, data is cut out from the electroencephalogram data in chronological order by 1024 points. Thus, in step 106, an electroencephalogram data set of about 1 second is obtained.

In step 107, the cut-out electroencephalogram data set is subjected to FFT analysis and decomposed into frequency components. In step 108, a power spectrum is obtained for each frequency band as shown in FIG. The frequency range of the brain wave includes alpha waves (8 to 13 Hz) which normally occur in a relaxed state.
Hz or less, and a frequency of 30 to 50 Hz is a noise component generated by blinking or the like. In step 109, 3
The ratio of the power spectrum of the frequency band corresponding to the noise component such as blinking of 30 to 50 Hz to the sum of the power spectrum of the frequency band corresponding to the frequency band of the brain wave of 0 Hz or less is calculated, and the unintended signal is collected. Is detected in the brain wave data obtained. When the ratio of the power spectrum of the frequency band corresponding to the noise component is 0.1 or more, it is considered that the brain wave data set includes the noise component, the brain wave data set is discarded, and the process proceeds to step 110. When the ratio of the power spectrum of the frequency band corresponding to the noise component is smaller than 0.1, the process proceeds to step 111.

In step 110, the extraction section is shifted by 786 points, and the process returns to step 105 to extract a new electroencephalogram data set.
09 is repeated. To prevent loss of information,
The electroencephalogram data set is cut out by overlapping by 1/4.

Next, at step 111, it is determined from the median time data of the electroencephalogram data set whether the data is a task state data, a rest state data, or a boundary state data extending between the task state and the rest state. Then, in the case of the task state, in step 112, the power spectrum for each frequency band is added as the task state data.
In the case of the rest state, in step 113, the power spectrum for each frequency band is added as the data of the rest state.
In the case of the data of the boundary state, the brain wave data set is discarded, and the process proceeds to step 110, where the cutout section is shifted,
It returns to step 105.

Next, in step 114, it is checked whether the presentation of the task and the rest is completed. If the presentation of the task and the rest has not been completed, the process proceeds to step 110, and the cut section is shifted.
Steps 5 to 113 are repeated. The processing of steps 101 to 114 is repeated while the task and the rest are presented to the subject.
When it is determined in step 114 that the presentation of the task and the rest is completed, the process proceeds to step 115.

In step 115, the α-wave power normalization circuit 15 normalizes α-wave power P (T), which is the ratio of the power spectrum of all frequency bands added in the task state to the α-wave power spectrum, and the rest state Then, the normalized α-wave power P (R), which is the ratio of the power spectrum of all the frequency bands and the α-wave power spectrum, is calculated. In step 116, the mental stress determination circuit 4 calculates a stress level MS = P, which is a ratio between the normalized α-wave power P (T) and the normalized α-wave power P (R).
Calculate (T) / P (R).

In step 117, the mental stress is determined based on the stress level MS. First, in order to explain the determination method, FIG. 7 shows brain wave data frequency power spectra at the time of task and at the time of rest. This power spectrum is calculated from the electroencephalogram collected while resting the eyes on rest at rest. As can be seen from the figure, it can be confirmed that in the transfer of the frequency spectrum when the rest is approximately one minute, the task is one minute, and the rest is one minute along the time axis, the low frequency components become prominent at the time of rest.

From this, the ratio of the α-wave power spectrum of the rest component to the power spectrum of the entire frequency band, that is, the normalized α-wave powers P (T) and P (R) are
This shows that the subject is in a relaxed state. Basically, a normal person has a smaller normalized α-wave power when a temporary stress is applied, and a larger normalized α-wave power in a relaxed state without a temporary stress. A clear difference occurs in the value of the wave power.

That is, under non-mental stress, as shown in FIG. 8A, a large difference occurs between the values of the normalized α-wave powers P (T) and P (R) in the task state and the rest state. On the other hand, in the state under the mental stress which is the background stress, the normalized α-wave powers P (T) and P (R) in the task state and the rest state as shown in FIG.
Will approach. Usually, there are many cases in which the worker cannot relax at the time of the rest in the mental stress of the worker, and this is called “type A”. Therefore, as shown in FIG. Normalized α-wave power P (T) and P (R)
If the stress level MS is 0.3 or less, a determination is made in step 118 that there is no mental stress.

As shown in FIG. 8B, the normalized α-wave powers P (T) and P
There is a slight difference in the value of (R), and the stress degree MS is 0.3
If it is larger and smaller than 0.7, step 11
At 9, a determination is made of "mental stress, possible". Further, as shown in FIG. 8C, the normalized α-wave powers P (T) and P
When the difference between the values of (R) is small and the stress level MS is 0.7 or more, it is determined in step 120 that “there is mental stress”. Step 101 of the flowchart shown in FIGS. 4 and 5 is a task presenting means of the invention.
Steps 102 and 103 constitute an electroencephalogram data simple measuring means, and steps 104 to 115 constitute an electroencephalogram data signal processing means.
Step 108 is a step in which the frequency power calculating means is used in
Steps 09 and 110 constitute an unintended signal removing means, and steps 112 and 113 constitute a frequency power adding means. Steps 117 to 120 constitute a mental stress determination unit.

As described above, according to this embodiment,
In each of the task state and the rest state, a normalized α-wave power, which is a ratio of a power spectrum of a frequency band corresponding to all frequencies corresponding to brain waves and a power spectrum of a frequency band corresponding to α waves, is calculated from brain wave data. By comparing the normalized α-wave power in the task state with the normalized α-power in the rest state, the presence or absence of subjective mental stress can be objectively determined. At this time, EEG data containing noise and EEG data at the boundary between the task state and the rest state are discarded, and only appropriate EEG data is used. Even if the data is mixed in the data, highly accurate determination is performed, so that an electrode for measuring brain wave data can be attached to the forehead, and simple measurement can be performed.

Next, in the mental stress judgment circuit,
FIGS. 9 and 10 show a second embodiment of the present invention in which the results of multiple measurements can be compared. FIG. 9 is a diagram showing the configuration, and FIG. 10 is a flowchart showing a part of the operation.
The mental stress determination circuit 5 includes a memory 16 for storing the previously calculated stress level, and the other configuration is the same as that of the first embodiment.

FIG. 10 is a part of a flowchart showing a determination algorithm when there is previous data. This flowchart is based on Steps 116 to 120 of the flowcharts shown in FIGS.
Instead of proceeding to, steps 121 to 125 are added. In step 116, the mental stress determination circuit 5 calculates the stress level MS, and then proceeds to 121.

In step 121, the previous stress level MS 'is read from the memory 16. In step 122, the current stress level MS and the previous stress level MS 'are compared. If the current stress level MS is larger than the previous stress level MS ', in step 123, the determination of "mental stress, increasing tendency from the previous time" is made. If the current stress level MS is equal to the previous stress level MS ', in step 124, a determination of "mental stress, no change from previous time" is made. If the current stress level MS is smaller than the previous stress level MS ', step 125
In the above, the judgment of "mental stress, tendency to decrease from the previous time" is made. Steps 121 to 125 of the flowchart shown in FIG. 10 represent the mental stress determination means of the present invention.

According to the second embodiment, when determining the mental stress, the previously calculated stress level is used as a scale to determine the currently calculated stress level, so that the effects of the first embodiment are added. In addition, it is possible to know the status of changes in mental stress.

In each of the above embodiments, the task of writing a circle on a predetermined sheet has been described as a task.
As shown in FIG. 7, when a circle 26 is entered in the same entry field 25 as in the first embodiment, a board 28 and a pen 29 capable of pen input to a computer 27 are used. You can also perform tasks while controlling the rate. In this case, task and rest time and achievement level management become easy, and the task can be given more effectively. A method is also possible in which a computer forcibly performs work such as mental arithmetic while controlling the execution speed and the error rate with a computer. The task is applicable as long as the content can give a subject mental stress. At this time, the subject is forcibly performed within a range that does not give up.

[0041]

As described above, according to the mental stress determination apparatus of the present invention, the subject's brain wave data is measured by the simple brain wave data measuring means while the subject is temporarily stressed, and the measured brain wave data is measured. Of the power spectrum corresponding to the entire frequency band of the brain wave and α
Calculates the normalized α-wave power, which is the ratio of the power spectrum of the frequency band corresponding to the wave, and focuses on the change to determine the mental stress. Objective determination with high accuracy based on physiological background can be performed for mental stress.

Then, by providing an unintended signal removing means, the electroencephalogram data including the noise signal is removed from the object of signal processing, so that even if there is a myoelectric signal such as blinking or other noise, it is not affected. Since the high accuracy of the EEG is ensured, the EEG data of the subject can be collected from the forehead using the simple EEG data measurement means, eliminating the hassle of dividing the hair and collecting the EEG data very simply. Can be.

In giving a task to a subject,
By presenting the time so that the subject alternately performs the task and the rest for a certain time by the timer,
A simple task can be given to the subject, and brain wave data can be easily collected.

In each of the task state and the rest state, the normalized α-wave power, which is the ratio of the power of the α-wave to the power in the entire frequency band, is calculated, and the normalized α-wave power of the task state and the normalization of the rest state are calculated. By determining the ratio of the α-wave power, it can be determined that there is mental stress when the ratio is large and that there is no mental stress when the ratio is small, so that an objective determination is easy. Also,
By calculating the ratio of the normalized α-wave power in the task state and the rest state in the previous measurement and the current measurement, it is possible to know the state of change in mental stress, and to improve the determination accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a use state of the first embodiment.

FIG. 3 is a diagram illustrating a task presentation timing in the first embodiment.

FIG. 4 is a flowchart illustrating a flow of an operation in the first embodiment.

FIG. 5 is a flowchart showing a flow of an operation in the first embodiment.

FIG. 6 is an explanatory diagram showing an addition procedure of an electroencephalogram power spectrum for each frequency band.

FIG. 7 is a diagram showing a frequency power spectrum of an electroencephalogram at the time of a task and at the time of rest.

FIG. 8 is a diagram for explaining the principle of determining mental stress in the first embodiment.

FIG. 9 is a block diagram showing the configuration of the second embodiment.

FIG. 10 is a part of a flowchart illustrating a flow of a determination operation according to the second embodiment.

FIG. 11 is a diagram illustrating another example of a task.

FIG. 12 is a block diagram showing a configuration of a conventional stress level measuring device.

FIG. 13 is a diagram illustrating a measurement principle of a conventional stress level measurement device.

FIG. 14 is a diagram illustrating a detection unit and a myoelectric signal.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 task / rest presentation device 2 simple electroencephalogram data measurement device 3 electroencephalogram data signal processing circuit 4, 5 mental stress judgment circuit 7 pulse wave detector 8 pulse counter 9 microcomputer 11 forehead mounting electrode 12 electroencephalogram data transfer device 13 frequency Power calculation circuit 14 Frequency power addition circuit 15 α-wave power normalization circuit 16 Memory 21 Ruled line 22, 25 Entry column 23 Paper 24, 26 Circled 27 Computer 28 Board 29 Pen 31 Pulse wave data 32 Shaped pulse 33 Occipital part 34 Forehead part 35 EMG signal

Claims (5)

[Claims] 1. A task presenting means for temporarily applying stress to a subject, an electroencephalogram data simple measuring means for measuring electroencephalogram data of the subject, and a frequency analysis of the electroencephalographic data measured by the electroencephalographic data simple measuring means to obtain an electroencephalogram. EEG data signal processing means for calculating a normalized α-wave power which is a ratio of a power spectrum corresponding to the entire frequency band to a power spectrum of a frequency band corresponding to the α-wave, and a normalized α calculated by the EEG data signal processing means A mental stress determination device comprising: a mental stress determination unit that determines mental stress based on wave power. 2. The task presenting means includes a timer,
The mental stress determination device according to claim 1, wherein a time is presented by a timer so that the subject alternately performs a task and a rest for a predetermined time. 3. The simplified electroencephalogram data measurement means collects electroencephalogram data from a forehead part, and the electroencephalogram data signal processing means includes a non-target signal removal means for detecting and removing noise signals such as blinks. The mental stress determination device according to claim 1 or 2, wherein: 4. The electroencephalogram data signal processing means calculates a frequency power spectrum for each frequency band from the electroencephalogram data detected by the electroencephalogram data simple measurement means, and calculates the frequency power spectrum by the frequency power calculation means. Frequency power adding means for adding each of the frequency power spectra obtained in the task state and the rest state for each frequency band, and in each of the task state and the rest state added by the frequency power adding means, α Α to calculate the normalized α-wave power, which is the ratio of the powers of the waves
Having a wave power normalizing circuit, wherein the mental stress determining means determines mental stress based on a ratio of the normalized α-wave power in the task state and the normalized α-wave power in the rest state. The mental stress determination device according to claim 1, 2 or 3, wherein the mental stress is determined. 5. The electroencephalogram data signal processing means calculates a frequency power spectrum for each frequency band from the electroencephalogram data detected by the electroencephalogram data simple measurement means, and calculates the frequency power spectrum by the frequency power calculation means. Frequency power adding means for adding the frequency power spectrum obtained in the task state and the rest state for each frequency band, and an α wave for the power in all frequency bands in each of the task state and the rest state added by the frequency power adding means. A normalization α-wave power that calculates a normalized α-wave power that is a ratio of the powers of the tasks, wherein the mental stress determination means includes a normalized α-wave power of the task state measured last time and a normalization of a rest state. The ratio of the α-wave power, the normalized α-wave power of the task state measured this time, and the normalized α-wave power of the rest state Based on the rate change of claims and judging the mental stress 1,2
Or the mental stress determination device according to 3.