**1.1. Psychological and physiological syndrome, emotion character of Internet addiction abusers**

The behavior, psychological characters, and physiological features of IA abusers were reported, such as mood-altering use of the Internet, guilt, emotional, and social withdrawal from real relationship, craving, and fatigue, and users are vulnerable to disease [3, 23–27]. In clinical contexts, IA has been associated with mental disorders, such as substance use disorder [28] and depressive disorder [29]. IA abusers experienced positive feelings (e.g., pleasure, gratifying sensations, security, calm, and belonging) or negative feelings (e.g., frustrate and lonely) when they are able or unable to use the Internet [2, 3], and they express emotional withdrawal symptoms when offline, such as anxiety and depression [5]. The perceived benefits keep people coming back to the addictive experience [30].

Emotion was one important character of IA and IGD. For example, users feel pleasure [23], control, and excitement when online, but feel anxiety and alone when offline [3], and shift emotional states through the Internet or online activities [5]. Emotion can be used to assess pathological Internet use [3]. The relationships among showing emotion, verbal expression of emotions, controlling negative physical reactions, coping, and anger management were examined, and emotion management skill was significant for IA levels. IA abusers exhibited bad emotion management skills [31]. IA and emotional intelligence tests was negatively correlated [32, 33]. Excessive Internet users expressed poorer intimacy, and had worse ability to express positive and negative emotions [34]. The withdrawal symptoms of Internet gaming disorder (IGD) may indicate an immediate emotional reaction [35]. The possible reasons why people addicted to online game were coping with negative emotions and stress, having entertainment, empowerment, mastery, control, excitement, and challenge [36]. The psychological syndromes regarding emotion of IA are listed in **Table 2**.

presents the parasympathetic activity, the activity of the vagus nerve, and they were related to emotions [42–44]. Lower resting vagally mediated HRV was associated with greater difficulties in emotional regulation, particularly a lack of emotional clarity and impulse control [43]. RSA is rhythmic fluctuations in the heart rate that are associated with respiration and is related to complex emotion responses and social behavior [45, 46]. Therefore, RSA can be utilized to investigate the relationship between emotions and the parasympathetic activity by noninvasive means [27]. People with higher resting RSA expressed less but reported much negative emotion as those with lower resting RSA. People with higher resting RSA tend to express more positive emotions and to suppress negative emotional expressions [47, 48]. RSA values positively link to positive emotions and negatively correlated to negative emotions [27, 44, 49]. People with IA presented lower parasympathetic activity, lower RSA values [50], and People with IGD exhibited higher sympathetic activity than people without IGD [51]. Respiration is vital for mental and physical functions, and is the only autonomic nervous function which can be both automatically and consciously regulated. For example, abdominal breathing can assist people in relaxing and regulating negative emotions. Respiration can be not only the index for emotions, but also a type of biofeedback to regulate or to change emotions. It was noticed that respiratory response and cardiac response importantly affect regula-

Investigation of Emotion Characters of Internet Abusers Using Psychophysiological Signals

http://dx.doi.org/10.5772/intechopen.73692

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IA is a serious problem and is worthy to be studied; however, little attention has been paid to its physiological characters of emotion. Emotions were both a response and an influential factor on IA, and were mainly studied using physiological signals. People use the Internet for several online activities; however, different online activities may be variables to affect the physiological responses and the regulation to emotional stimulation. The general IA abusers

Emotional induction experiments using several emotional induction materials were conducted. The psychological characters were obtained using self-reports and questionnaires, and physiological signals were collected using respiratory belts and ECG. The relationship and differences in respiration between people with IA and people without IA, RSA, and HRV were tested, and the regulation of the parasympathetic activity in emotional states was discussed.

Materials include emotional induction materials, emotional intensity questionnaire, IA scale (Chen Internet Addiction Scale), and physiological signal acquisition equipment. Emotional pictures selected from International Affective Picture System (IAPS) [52], and emotional film clips selected from Taiwan corpora of Chinese emotions and relevant psychophysiological data [53] were utilized for emotional induction materials. Emotional pictures (anger, disgust, fear, sadness, happiness, and surprise pictures), and emotional film clips (anger, fear, sadness, happiness, and fear films) were adopted. Anger, sadness, and fear are negative emotions, while happiness and surprise are positive emotions. Participants rated their emotional

tory functions, and may also be a regulation means to IA.

**2. Emotional induction experiment**

and specific IA (IGD) abusers should be considered in the further study.

**2.1. Emotional induction material and experimental instrument**

Concerning the physiological syndrome of IA, the autonomic nervous responses of highrisk IA (HIA) abusers was studied. The blood volume pulse and respiratory response of HIA abusers would increase, but peripheral temperature and skin conductance would decrease [22]. Heart rate variability (HRV) is one index of autonomic nervous system (ANS) activity. The high frequency percentage acquired from HRV of HIA abusers was lower, but the low frequency percentage of HIA abusers was higher than that of LIA abusers [37]. The results showed that the sympathetic nervous activities of HIA abusers were stronger, and the parasympathetic nervous activities were weaker than that of LIA (low-risk IA) abusers.

Emotion conveys psychological (subjective) and physiological (objective) information, and can be observed and assessed through psychological methods such as self-reports, interviews, questionnaires, and through physiological reactions such as the heart rate, respiration, facial expression, and particularly ANS activities [38]. The ANS which contains the sympathetic nervous system and parasympathetic nervous system, which has antagonistic effects, plays an important role in regulation of physiological reactions and emotions. The emotion-related responses derived from ANS are cardiovascular responses, respiratory responses, and electrodermal responses. These responses usually cannot be manipulated consciously [38–41], and can be measured using noninvasive methods. For example, heart rate variability (HRV) and respiratory sinus arrhythmia (RSA) acquired from electrocardiography (ECG), a noninvasive physiological signal, was a widely adopted index of the regulation of ANS activities. HRV presents the regulation of sympathetic activity and parasympathetic activity, and RSA


presents the parasympathetic activity, the activity of the vagus nerve, and they were related to emotions [42–44]. Lower resting vagally mediated HRV was associated with greater difficulties in emotional regulation, particularly a lack of emotional clarity and impulse control [43]. RSA is rhythmic fluctuations in the heart rate that are associated with respiration and is related to complex emotion responses and social behavior [45, 46]. Therefore, RSA can be utilized to investigate the relationship between emotions and the parasympathetic activity by noninvasive means [27]. People with higher resting RSA expressed less but reported much negative emotion as those with lower resting RSA. People with higher resting RSA tend to express more positive emotions and to suppress negative emotional expressions [47, 48]. RSA values positively link to positive emotions and negatively correlated to negative emotions [27, 44, 49]. People with IA presented lower parasympathetic activity, lower RSA values [50], and People with IGD exhibited higher sympathetic activity than people without IGD [51]. Respiration is vital for mental and physical functions, and is the only autonomic nervous function which can be both automatically and consciously regulated. For example, abdominal breathing can assist people in relaxing and regulating negative emotions. Respiration can be not only the index for emotions, but also a type of biofeedback to regulate or to change emotions. It was noticed that respiratory response and cardiac response importantly affect regulatory functions, and may also be a regulation means to IA.

IA is a serious problem and is worthy to be studied; however, little attention has been paid to its physiological characters of emotion. Emotions were both a response and an influential factor on IA, and were mainly studied using physiological signals. People use the Internet for several online activities; however, different online activities may be variables to affect the physiological responses and the regulation to emotional stimulation. The general IA abusers and specific IA (IGD) abusers should be considered in the further study.
