estimating brain vigor in discussion from behavioral reaction for stressful load

International Research Journal of Computer Science (IRJCS) ISSN: 2393-9842 Issue 02, Volume 3 (February, 2016) www.irjcs.com

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Estimating Brain Vigor in Discussion from Behavioral Reaction for Stressful Load

Shun Okamura* Second Author Yusuke Kajiwara Ritsumeikan University, Ritsumeikan University, Ritsumeikan University,

Siga:Japan Siga:Japan Siga:Japan Abstract— To create new idea, young persons often have one-to-one discussion with their mentors.In such meeting, heavy stressful loads are often imposed on young persons. We should improve the quality of discussion in progress so that the discussion should bring about a good new idea. The paper proposes a method which estimates the brain vigor of idea proposers in discussion from their behavioral reactions under stressful loads. In this method, behavioral reactions are measured with web-cameras because the discussion participants do not have to wear any sensors. The method figures out the spectrum of the upper half body, the hip, and the lower half body. It discriminates behavioral reactions under stressful loads from the spectrum using Random Forest. The experiment revealed we can estimate the brain vigor of a person from behavioral reactions of his hip at 70% in the f-measure. With the method, a mentor can proceed with discussion which is promising to create a good idea, because he can judge the brain vigor of the person refining the idea.

Keywords— brain vigor, meeting, discussion, reaction, stressful load

I. INTRODUCTION

We are requested to issue new ideas one after another. The best way to create new ideas is to have a one-to-one discussion between a young person and a mentor. Generally, in meetings for such discussion, a mentor criticizes ideas a young person proposes. The participants in the meeting stay in the forced communication situation[1], where they must continue to issue opinions. Compared with meetings of many people, the participants of the one-to-one discussion must make various kinds of decision in a short time. Decision making is an act to find the best solution from many substitute plans. In the decision making, much psychological stress is imposed on the participants, because their brains handle many processes to lead the best solution. Psychological stress consists of stress of cognitive aspects and stress of emotional aspects. Stress of cognitive aspects appears when we are thinking, while that of emotional aspects appears when our emotion rises and falls. This study refers to loads brought by the psychological stress as stressful loads.

In one-to-one discussion, we have high possibility to create a good idea in a short time. However, it also has a danger to end in a fruitless meeting, as shown in the following scenario. The mentor in the discussion has a right to assess the achievement of the young person. A young person tries to present an excellent idea to the mentor. The mentor asks questions to him when the mentor is not convinced with his idea. The question affects on the young person trying to get good mentor evaluation. If the question is a sever one, a big stressful load is placed on the young person. The stressful load degrades his brain vigor. The low brain vigor prevents him from considering a proper solution. The young person who cannot find any appropriate answer is likely to propose an unsuitable solution, taking an illogical short-cut[2]. The solution throws the discussion into confusion, which degrades the brain vigor of the young person. The young person running into the negative spiral cannot give any utterance, enlarging his stressful loads. Since the young person feels the excessive stressful loads, they cannot continue proper arguments any more. The participants waste their time without any fruitful result. Especially, the young person loses his confidence, because he has failed in discussion. To avoid such situations, we should always pay attention to the brain vigor of the meeting participants. If excessive digression is found in the brain vigor, we should break the discussion to refresh the brain vigor of the participants, especially the young person. However, it is hardly possible to know the brain vigor during discussion.

This study proposes a method which estimates the brain vigor from actions appearing under stressful loads during discussion. The study refers to actions appearing under stressful loads as behavioral reactions. It is preferable for the method to be independent from individual difference of behavioral reactions from the view point of the versatility of the method. The method estimates the brain vigor of a person issuing an idea, focusing on behavioral reactions of his hip, which is independent from individual difference.In this method, behavioral reactions are measured using a web-camera because the discussion participants do not have to wear any sensors. As a result of an experiment to show the effectiveness of the method, the F-measure was 0.72 when we recognize the brain vigor of discussion participants. With the method, a mentor can proceed with discussion which is promising to create a good idea, because he can judge the brain vigor of the person refining the idea.




II. DETERMINING BRAIN VIGOR USING BEHAVIORAL REACTION OF HIPS

A. Relevance between Behavioral Reaction and Brain Vigor We have much opportunity to make decisions in discussion. When people make many decisions, they have many

stressful loads. Working memory is strongly related to the mechanism which makes behavioral reaction appear under stressful loads. Working memory holds structures or processes for people to work keeping transient information. It plays an important role to speak, read, write, or calculate in daily life. The model of Baddeley \& Hitch is most famous in models of working memory[5][6].

Fig. 1 Relevance between working memory model and decision-making process

Fig.1 Relevance between the model and decision-making process. Decision-making is a process to take an action for a

stimulus from the surrounding environment. When people receive stimuli, they recognize the current situation. They make decisions to take actions which affects the environment. Working memory has a role to allocate attentional resources for various stimuli in the current situation. It is referred to as situation awareness of the process. The model of working memory has four components: episodic buffer, phonological loop, visuospatial sketchpad, and central executive. The visuospatial sketchpad, the phonological loop, and the episodic buffer are short-term memory. The visuospatial sketchpad retains visuospatial information. The phonological loop retains phonological information. The episodic buffer takes information of long term memory. In addition, the episodic buffer retains semantic information or multidimensional expression, using the above three types of information. The central executive controls these three components. It controls action and thought, dealing attentional resources for each component. Discussion oppresses heavily the phonological loop to retain the other person's speech. It uses excessively the visuospatial sketchpad to retain the other person's facial expression or gesture. It is important to manage flow of interactions along with the time in discussion. Discussion also oppresses the episodic buffer heavily, because it needs to take information from long term memory and to retain the flow of the interaction. The central executive manages all of the components for reading information and retaining it. As a result, working memory is used intensively.

In addition, stresses of emotional aspects appear in actual discussion. They oppresses working memory more and more. It is a serious factor in discussion that working memory is used excessively. It brings about stressful load in discussion. If working memory deals attentional resources in a proper way, people can recognize the situation around them. They can make a right decision. They can control impertinent action in discussion without any effort. Examples of impertinent actions in discussion includes nervous knee‐shaking, rapping on a desk with a pen or a finger. People cannot assign attentional resources to control of impertinent action in discussion. In discussion, they must allocate attentional resources to control of the components, because discussion needs decision-making frequently. As a result, stressful loads affects working memory, which makes habitual actions appear.

This study refers to the habitual actions as behavioral reactions for stressful loads. The behavioral reactions express the state of the brain experiencing stressful loads. Stressful loads lead to decrease of attention by the excessive use of working memory. They give negative effects on brain vigor. It implies that the brain vigor is known from behavioral reactions to some extent. This method estimates the brain vigor in discussion from behavioral reactions coming from stressful loads.




B. Method Overview

Fig.2 shows the outline of the method. We use Web-cameras as sensors, because they are inexpensive. They can measure the movement of the persons away from them. In the method, a web-cameras is located in each of the left and right sides of discussion participants. Each web-camera captures the movements of the persons. Let the location of the target be represented with coordinate (x, y), where x and y represent the horizontal and vertical location, respectively. The method gets coordinate (x, y) of the left side and the right side of the hips of the discussion participants with the two web-cameras. These movements are converted to frequency with Fourier transformation. The classifier is trained with combinations of the frequency and the brain vigor with a machine learning algorithm. The trained classifier estimates the brain vigor of the of discussion participants from the frequency of hip movement. The method enables us to monitor the brain vigor of the participants during discussion.

Fig. 2 Method Overview

C. Behavioral Reaction of Hips

This study estimates the brain vigor from behavioral reaction for stressful loads in discussion. We can estimate the brain vigor in higher accuracy, observing habitual actions peculiar to each person. This method supposes a face-to-face discussion. If we want to treat many persons in the method, the method should be specialized for the discrimination of each person. It is inefficient because the classifier needs to be trained for the person. The method specialized for the discrimination of specific persons is not available to measure the brain vigor of the persons who join discussion by chance. This study proposes the method enabling us to estimate the brain vigor of any person.

Accordingly, we need to focus on body parts whose movement does not vary with persons. At the same time, it is prefereable that no action other than behavioral reactions appears in the parts. Movements other than behavioral reaction like gesture are likely to appear in parts in the upper half of the body. Some people frequently move parts of the lower half of bodies, while others do not. Hips Since hips do not have many patterns of movements. The method focuses on behavioral reaction in hips. Under the stressful loads, it is considered that people twist their bodies back and forth on their hips as behavioral reaction. For another example, people correct their postures, pushing their body toward the backs of chairs to straighten themselves. This method uses Fourier transformation to get periodic patterns of behavioral reactions of the hips for stressful loads.

III. EXPERIMENT A. Overview

This experiment confirms usefulness of this method. The experiment purpose is to estimate brain vigor in discussion

from behavioral reactions for stressful loads. Test subjects are five male university students. Each of the five male students had discussion with a teacher in a face-to-face manner. The rotary chair with a caster was used in this discussion. The desk and the chairs were ones all of them are accustomed to use. The theme of discussion is the graduation study of each male student. Each male student presented the slide of his own study for the teacher. All of the presented study contents include three components of a background, a method and an experiment. The teacher asks many questions to him in order to impose heavy stresses on him. We measure the behavioral reactions with two web-cameras. The two web-cameras are installed in the left and right sides of the discussion participants by 2 meters away from them. A paper maker is put on the three parts of the student body, an elbow, a hip and a knee for the analysis. We took time for the students to be accustomed while they explain the slides.




Movements of an elbow and a knee are often connected with those of a wrist and an ankle, because an elbow and a knee is located in the center of an arm and a foot, respectively. In this experiment, an elbow is focused on to collect the movements of the upper half of body, while a knee is assumed to correspond to the movements of the lower half of body.

After a student presented his slides, he took the flicker test for about one minute. After that, the experiment started with questions f from the teacher. The question lasted for forty minutes. This question time consists four phases related to the following topics: a background, a method, an experiment and a chat. Each phase is ten minutes. The teacher asked four kinds of questions in each of the first three phases, to make the stressful loads to every student as equal as possible. The questions are as follows.

The first question asks a student to explain advantages of the presented plan from other plans. In the second question, the teacher points out problems of the presented plan. The teacher makes him consider a

counter measure. The third question digs into the logicality of the presented plan. It also asks the utility and novelty of the plan.

In the last, the chat phase is held for a conversation separated from the study contents. In the phase, we make the conversation flow to transfer from study topics to idle talks as natural as possible, talking future works of the study or future jobs after his employment. In the phase, we aim to see difference of discussion on the study taking for stressful loads from the conversation with a few stressful loads. In this experiment, an alarm rings every ten minutes. The student does a flicker test every ten minutes, after the teacher ended the phase at good timing of an end of the discussion or the conversation. Students take five times flicker tests in total. B. Experiment Evaluation

The random forest is used to see the variable importance [8]. 5-fold-cross-validation is used for five subjects. We give the power spectrum of the frequency-domain of an elbow, a hip, and a knee. In this experiment, a smart phone is placed on the desk, so that the student can tap it when he feels a stress. The smartphone records the lap time at the timing he feels a stressful load. The student looks over the video recording the discussion after an experiment. Overviewing the video, the student specifies the reason of each stress he reports: stress of emotional aspects or stress of cognitive aspects.

C. Flicker Test In this experiment, a flicker test is used to measure brain vigor quantitatively. The value is called “Critical Flicker

Fusion (CFF)”. Suppose a flash light is decreasing flash interval speed gradually from the high state (e.g. 60Hz) of the flash frequency. People begin to feel flickering of the light seeming to light up so far. CFF is the flash frequency value of the timing.

CFF has been used as the index of brain fatigue [9]. CFF is also related to brain vigor. CFF gets higher because of the factor which raises brain activities raises CFF [11], such as caution, excitement of emotion, tension, and muscular movement. On the contrary, CFF gets lower for the factor which makes brain activity fall [11]. For example, fatigue, sleepiness, rest and boredom make CFF fall. This study refers to these factors of brain vigor as an accelerator factor and a brake factor, respectively. Accelerator factors such as caution and tension occur when discussion starts, which makes CFF increase along with a rise of the brain vigor. After that, brake factors such as fatigue and boredom occur, as the discussion proceeds. CFF falls along with the fall of the brain vigor. The transition of CFF is related to the change of the brain vigor. To measure the quantitative value of the brain vigor, this experiment uses application software “Flicker Health Management System” which works on a smart phone [10].

D. Experiment Results

1) Stressful Load and Brain Vigor: Fig.3 shows relationships between stressful loads and brain vigor. The value of the right and the left vertical axis indicate CFF and the number of times which felt a stressful load, respectively. The horizontal axis shows the four phases, each of which lasts for ten minutes. This result shows the brain vigor of the four people falls in the chat phase. It seems to be caused by decrement of accelerator factors such as caution and tension.




Fig. 3 Relationships between Stressful Loads and Brain Vigor

These graphs imply correspondence between the number of times subjects feel stressful loads and the brain vigor. Table. I shows the correlation between the number of times subjects feel stressful loads and the brain vigor. In the table, stressful loads count up loads coming from both of stress of emotional aspects and stress of cognitive aspects. As a result, a weak correlation is found between them. Note that stress of emotional aspects affects on the brain vigor more than stress of cognitive aspects.

TABLE II - CORRELATION TABLE

STRESSFUL LOAD EMOTIONAL ASPECTS CONGNITIVE ASPECTS BRAIN VIGOR 0.30 0.33 0.20

2) Identification Result: Fig.4 shows the graph of the precision, the recall and the f-measure in the identification. The rate are almost same in the precision, the recall and the f-measure. The f-measure was 0.53, 0.51, and 0.72. in elbow, knee, and hip, respectively. Since the f-measure is around 0.5 in elbow and knee, it is difficult to distinguish the brain vigor from behavioral reaction of the upper half of the body and the lower half of the body. However, it is possible to distinguish the brain vigor from behavioral reaction of the hip because of the high value in the f-measure. If we focus on behavioral reaction of the hip, we estimate the brain vigor in discussion, avoiding influence of the individual variation.

Fig. 4 Precision, Recall and F-measure




TABLE II -VARIABLE IMPORTANCE ELBOW HIP KNEE

1 X, left, 10 to 15Hz X, right, 0 to 5Hz Y, right, 0 to 5Hz 2 X, left, 15 to 20Hz X, right, 25 to 30Hz Y, right, 5 to 10Hz 3 Y, left, 0 to 5Hz X, right, 15 to 20Hz X, right, 25 to 30Hz 4 Y, left, 5 to 10Hz X, right, 20 to 25Hz X, right, 20 to 25Hz 5 Y, left, 5 to 10Hz X, right, 5 to 10Hz Y, right, 25 to 30Hz

20 Y, right, 25 to 30Hz X, left, 5 to 10Hz Y, left, 20 to 25Hz 21 X, right, 25 to 30Hz X, left, 15 to 20Hz X, left, 10 to 15Hz 22 Y, right, 10 to 15Hz Y, left, 15 to 20Hz Y, left, 10 to 15Hz 23 X, right, 20 to 25Hz X, left, 10 to 15Hz X, left, 5 to 10Hz 24 Y, right, 15 to 20Hz X, left, 20 to 25Hz Y, left, 5 to 10Hz

Table.Ⅱ shows the average of variable importance in the 5-fold-cross-validation, changing values of the explanatory variable every 5 Hz.The table enumerates top 5 and bottom 5 frequencies in terms of the variable importance. In this experiment, the low frequency zone ranges from 0 to 10 Hz, while the high frequency zone from 10 to 30 Hz. The variable importance of the left elbow is high, but that of the right is low. The variable importance of the right of the hip and the knee is high, while that of the left is low. In case of the elbow and the knee, the frequency calculated with X-coordinate and y-coordinate is scattered into the top and the bottom. On the other hand, the frequency of the hip movement calculated with X-coordinates is concentrated in the top and the bottom. In summary, behavioral reaction of the left elbow is important, but the right is not important. On the contrary, the behavioral reaction of the right knee is important, but the left is not important. The behavioral reaction of the right x-axis of the hip is important, and the left x-axis is not important. The frequency of the movement of the right hip calculated with x-coordinate is important to judge the brain vigor.

IV. DISCUSSION

A. Correlation between Stressful Loads and Brain Vigor Experiment result indicates the weak correlation between the number of times subjects feel stressful loads and the

brain vigor. However, stress of cognitive aspects does not have correlation with the brain vigor. It seems to come from the mechanism of cognition to emotion. Lazarus's emotion cognitive theory considers emotion appears after a cognitive process [3][4]. This means that emotion appears after cognition of questions, when we are asked a question in discussion.

For example, negative emotion appears, when someone points out a weak point of the study with a question in discussion. After the question is recognized as a sever one, the emotion is exaggerated because we cannot avoid it in discussion. The emotion works as a stressful load. Subjects often feel negative emotion at the same timing of the raise of the brain vigor because of the negative emotion. However, the brain vigor is seldom activated at the timing of the raise of the cognitive stress. Therefore, subjects would tend to feel stressful loads as stress of emotional aspects more than stress of cognitive aspects. B. Variable Importance of Hips

In this experiment result, the variable importance of the right side of the hip is high. The examination of the video recording the experiment reveals the subjects often place their weight on the left sides of their bodies. The variable importance seems to be caused by the fact. The subjects often moved their chair back and forth wards. They also turned the chairs many times. It they put their weight evenly on the both sides, the difference of the right and the left sides is hard to appear in the variable importance, because both sides have the same movement. However, the subjects often put their weight only on the left sides. When they return their posture to even one, they turn the right sides of their hips, fixing the left sides of their hips, , because subjects have a center of gravity on the left side. This movement is considered to make the variable importance of low frequency zone of the right sides of hips higher.

In addition, we found high importance in the movement in low frequency zone of the vertical position of the right knee. It is coincident with the movement of a knee which is larger than that of a hip when a subject changes the posture into an even one. In addition, the movement to shake the right knee in the vertical way would also increase the high importance. Since each subject puts the weight on the left sides, room of the space is found between the right side of the hip and the chair. Because of it, we can confirm subjects swing the right knee. This movement seems to increase the variable importance in high frequency zone of the right hip. This discussion implies the method can measure the brain vigor through the observation of behavioral reactions of the hip side the subjects do not put their weight intensively. On the other hand, to improve the precision of this method, we can introduce a personal specialization, based on habits of the personal movement for learning data.




V. CONCLUSION The method estimates the brain vigor of a person issuing an idea, focusing on behavioral reactions of his hip in

discussion. An idea proposer is likely to take an illogical short-cut because of stressful loads in a one-to-one discussion than in meetings of many people. The method estimates brain vigor of discussion participants from their behavioral reactions coming from stressful loads, using web-cameras which take their natural behavior. An experiment result shows the method can estimate the brain vigor from behavioral reaction of the hip at 70% in the identification rate. With the method, a mentor can judge the brain vigor of the person refining the idea. He can proceed with discussion so that it certainly creates a good idea.

ACKNOWLEDGMENT

I am deeply grateful to Prof. Hiromitsu Shimakawa who provided helpful comments and suggestions. I also give my thanks for Yusuke Kajiwara who help me assemble subjects for experiment. I am grateful for all people for attending experiment. Finally, I gratefully appreciate to all members and colleagues of Data Engineering Laboratory from Ritsumeikan University, to complete my thesis.

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estimating brain vigor in discussion from behavioral reaction for stressful load

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