Introduction

Since the introduction of gaming disorder (GD) as a tentative clinical condition in the current, fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) [1], the empirical evidence on this condition has steadily grown. In recent years, psychological and neurobiological findings have brought clarity to the debate surrounding the classification of GD. This led to the inclusion of GD as a recognized condition subsumed under the category “Disorders due to substance use or addictive behaviors” in the International Classification of Diseases (ICD-11) [2].

Besides the relevant focus on the assessment of neural and psychological similarities and differences between substance use disorders, gambling, and GD, certain scientists focused their research aims on the investigation of possible self-concept deficits as one influential factor for the development of GD. One reason for this approach is that particularly adolescents bear a higher risk for GD [3, 4] and adolescence is regarded as the phase in which a healthy self-concept is the main developmental task [5, 6].

Mummendey [7] defines “self-concept” as a subjective description and evaluation of the own character, skills, and capabilities based on experiences and comparisons with representations of an ideal self (i.e., on how one would like to be) [7]. The ideal self is the product of social comparisons, which is influenced by family members, peer groups, society, and media. The term “self-concept” was also used synonymously with the concept of global self-esteem described by Rosenberg as the “individual’s positive or negative attitude toward the self as a totality” [8]. Ryan and Brown [9] assume that optimal self-esteem and therefore self-concept, respectively, should not originate from seeking esteem. Instead, the self-concept is expected to be fostered by cultivating awareness of one’s basic needs for autonomy, competence, and relatedness, as well as by seeking out relationships, vocations, and interests in which those needs can truly be satisfied.

Therefore, the self-concept emerges from a subjective perspective influenced by certain factors (e.g., social environment or convictions from positive and negative learning experiences). Furthermore, self-concept is regarded as a construct involving a physical (e.g., the evaluation of one’s own body image), a social (e.g., social competence vs. social anxiety), an emotional (e.g., recognition, expression, and regulation of one’s own feelings), and an academic domain (e.g., being disciplined, persistent). It always emerges from cognitive and affective self-evaluation processes that lead to a certain behavior. The main aspects of the emotional self-concept domain are comprised in the model of emotional intelligence of Mayer and Salovey [10]. It postulates the perception, adequate use, understanding, and management of emotions, which mostly occur in the context of relationships, to be the main interrelated abilities for emotional intelligence [10, 11].

Self-Concept and Identification with Virtual Characters in Media and Games

McCall and Simmons [12] already described that media have a significant impact on the development of the self-concept. Media enable an individual to adopt certain roles (e.g., that of a protagonist in a movie) by creating an imaginary idealized picture of oneself, how one would like to be and behave in social situations. These roles can be easily adapted to their own personality traits and therefore become part of the self-concept [12]. Before the Internet witnessed its boom in the 1990s, some researchers assumed that media represented a positive information source that could constantly modify and validate the self-concept [13]. However, in today’s world, which is characterized by permanent digital availability, this exclusively positive assumption can no longer be maintained. In particular, in adolescence—during which a person forms the self-concept—an increased confrontation with idealized virtual characters can lead to high discrepancies between the self-image and an ideal self [14]. In combination with low social appreciation, these discrepancies are susceptible to induce feelings of incompetence, anxiety, fear, and depression.

Studies that analyze the content of popular video games found that women in games are typically stylized as idealized sex objects with large breasts and thin hips, while male characters were portrayed as unrealistically muscular [15,16,17]. Furthermore, Barlett and Harris [18] found that male and female participants displayed significantly lower body self-esteem after playing a video game that emphasized the ideal male or female body, respectively. These findings were independent of the time spent playing video games and body mass index. They might also indicate an increased identification with the avatar in Massively Multiplayer Online Role-Playing Games (MMORPG)Footnote 1 players.

In this line, Klimmt, Hefner, and Vorderer [19] assume in their “self-discrepancy hypothesis” that gamers use their avatar to alleviate psychological tension by temporarily reducing the distance between themselves and their ideal self. Indeed, many studies in the literature indicate self-concept deficits and increased identification with one’s own avatar have an impact on the development of GD.

Imaging Studies on Self-Concept and Theory of Mind

Functional imaging studies on neural correlates of self-concept or avatar identification use different paradigms that are able to assess different facets of these two constructs.

In most functional imaging studies, the self-concept was assessed by means of self-referential and self-recognition paradigms. During self-referential tasks, participants are asked to evaluate their own personality traits, physical appearance, preferences, or thoughts. Resulting neural activation patterns are then compared with those during the evaluation of a close friend or a famous person [20,21,22]. Thus, self-referential tasks comprise the conscious cognitive evaluation of the physical, academic, social, and emotional self-concept domains. However, self-recognition paradigms, in which participants see pictures of their face or whole body relative to close friends or a famous person [23], mainly involve evaluating the physical aspect of the self-concept. In a recent meta-analysis, Hu et al. [24] compared neural correlates of self-face recognition and self-referential paradigms. The conjunction analyses revealed that both self-recognition and self-referential processing consistently activate the right anterior cingulate cortex (ACC), the left inferior frontal gyrus (IFG), and left anterior insula [24]. Besides these findings, some studies reported activation in the ventral striatum during self-affirmation tasks, in which a participant is asked to reflect on personal values, strengths, and attitudes [25,26,27]. The ventral striatum has often been reported to play a key role in reward anticipation (e.g., gain of money, drug craving) and social learning behavior [25, 28,29,30,31,32]. One explanation for the activity in the ventral striatum during self-affirmation might be the rewarding aspect that individuals strive to maintain a positive view of themselves [25, 27].

Identification with an avatar in a game entails psychological interpersonal skills, such as Theory of Mind (ToM) abilities [33]. ToM is defined as the “the ability to attribute and reason about mental states of others” [34]. Thus, it can be assumed, that the ToM entails the reflection and knowledge about the “affective” and “cognitive” states of another person.

In imaging studies, neural correlates of ToM have been investigated among different paradigms, aiming at individuals making spontaneous assumptions about the mental states of others. One frequently used task is the False-Belief Task, which assesses the ability to recognize that people who do not know a certain detail of the story will make false assumptions about the circumstances of a presented situation, by means of short stories [35].

Available meta-analytical findings indicate that the temporoparietal junction (TPJ), which entails the inferior parietal lobule (IPL) and the angular gyrus (AG); the superior temporal gyrus (STG); the posterior superior temporal sulcus (STS); the precuneus; and the medial prefrontal cortex (MPFC) [36, 37], might be specific neural correlates for ToM processing.

Methods

The following systematic review aims to give an overview of self-report and functional neuroimaging studies on self-concept, as well as avatar identification in GD. Three literature researches were conducted based on the databases Pubmed and PsycINFO. An overview of the steps of the literature research is given in Figs. 1, 2, and 3. Concerning self-esteem the key words [(gaming OR online gaming OR multiplayer) AND (self-esteem OR self-worth)] were searched.

Fig. 1
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Literature research for articles concerning psychometric findings on self-esteem. KEYWORDS: [(gaming OR online gaming OR multiplayer) AND (self-esteem OR self-worth)]

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Fig. 2
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Literature research for articles concerning psychometric findings on self-concept domains and avatar identification. KEYWORDS: [(gaming OR online gaming OR multiplayer) AND (self-concept OR identity OR identification OR Avatar OR social competence OR emotional competence OR body image)]

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Fig. 3
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Literature research for articles concerning fMRI studies on self-concept domains and avatar identification. KEYWORDS: [(gaming OR online gaming OR multiplayer) AND (self-concept OR identity OR identification OR avatar OR social competence OR emotional competence OR body image) AND fMRI]

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Regarding self-concept we searched for the terms [(gaming OR online gaming OR multiplayer) AND (self-concept OR identity OR identification OR avatar OR social competence OR emotional competence OR body image)].

The corresponding functional magnetic resonance imaging (fMRI) studies were based on the search terms [(avatar OR self-concept) AND (game OR gaming OR multiplayer) AND fMRI].

Studies were screened using the following pre-defined inclusion criteria. Studies had to (i) include the relation between GD and self-concept in self-report or functional imaging studies, (ii) be published in a peer-reviewed journal, and (iii) be available as full text in the English language. No publication time period was specified for the literature search because the number of existing studies in this field of research is relatively small (i.e., most being published between 2007 and 2019). Besides, all studies were evaluated regarding publication date, study designs, and measurements for GD (coverage of the DSM-5 criteria and psychometric properties according to the reviews of King et al. [38] and King, Haagsma, Delfabbro, Gradisar, and Griffiths [39]).

Results

The final sample of studies consisted of 49 journal articles assessing self-esteem and/or self-concept domains, avatar identification, and neurobiological correlates. Among these, we reviewed 17 findings concerning self-esteem, 33 findings (5 studies overlapped with the studies on self-esteem) that included at least one of the self-concept domains (physical, social, academic, or emotional) or avatar identification, and six neurobiological findings (two of them overlapped with the studies on self-concept domains).

Self-Esteem

As is shown in Table 1, 17 studies assessed self-esteem in participants with GD as well as in normative gamers. According to the recent review of King et al. [38], five studies applied instruments based on DSM-5 criteria for the assessment of GD [48, 57•, 62, 69] and seven studies used tools with relatively high evidential support for their psychometric properties [40••, 57•, 62, 68, 73, 74••]. Seven studies recruited their participants in schools [45, 54, 60, 66, 68, 71, 75•]; seven in game forums or social media forums or via advertisement [40••, 42•, 48, 57•, 62, 69, 77]; two via telephone [73, 74••]; and two in outpatient care [51, 65].

Table 1 Self-report studies on self-esteem
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Significant associations between lower self-esteem and GD were found in 15 out of 17 studies [42•, 48, 51, 54, 57•, 60, 62, 65, 66, 68, 69, 71, 73, 74••, 75•]. When taking a closer look at the reported correlation coefficients, the studies find weak and medium-sized correlations, between .12 [48, 57•, 60, 62, 66, 68, 71, 75•] and .43 [69, 74••]. Only two studies did not confirm this association between self-esteem and GD [40••, 45••].

The study research revealed three longitudinal studies of major importance. Wartberg et al. [74••], as well as Lemmens et al. [68], showed in cross-lagged panel design studies on adolescents that a decreased self-esteem at baseline predicted GD scores after 1 year. On the other hand, Baysak et al. [40••] did not confirm this longitudinal predictive relation in adult MMORPG gamers after 2 years. The authors did not observe that changes in GD scores after 2 years were significantly associated with changes in self-esteem.

Self-Concept Domains and Avatar Identification

Our research (Table 2) revealed 33 studies investigating self-concept domains as well as avatar identification in participants with GD as well as in normative gamers. Only two studies applied instruments based on DSM-5 criteria for the assessment of GD with good psychometric properties [57•, 125•] and twelve studies used tools with relatively high evidential support for their psychometric properties [41, 57•, 68, 96, 101, 119, 122, 125•, 135, 143, 145, 148••]. The studies assessing the specific domains of the self-concept, as well as the degree of avatar identification in gaming addicts, mostly used self-rating questionnaires (see Table 2). Four applied instruments asked the participants to evaluate their actual self, their ideal self, and their own avatar in body image as well as in social and emotional competences [65, 77, 116, 129•]. To our knowledge, to date, there are only two studies on adolescents investigating the relationship between academic self-concept (measured by self-evaluation of school performance) and GD [132•, 139•]. Sixteen out of 33 studies recruited their participants in schools [3, 41, 45, 68, 75•, 85, 87••, 103, 109, 116, 132•, 133, 135, 139•, 141, 148••]; eleven in game forums or social media forums or via advertisement [57•, 77, 79, 80••, 90, 125•, 126, 129•, 143, 145, 147]; one via telephone [101]; and five in outpatient care [51, 65, 96, 119, 122].

Table 2 Self-report studies on emotional, social, and physical self-concept domains and avatar identification
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Physical Self-Concept

Regarding the physical self-concept, our literature research revealed only five studies, four of which reported a negative body image, to be related to GD [65, 119, 122, 125•]. In their online survey, Lopez-Fernandez et al. [125•] reported a medium-sized correlation between negative body image in female gamers and GD. Three studies observed that gaming addicts reject their body image to a higher degree as compared with non-addicted participants [65, 119, 122]. However, the study samples, recruited from an outpatient clinic, were quite small. Only one investigation did not confirm these results [57•]. It should be noted that most of the studies assessed body image with different instruments. The online survey study of Kircaburun et al. [57•] assessed the body image by means of the Body Image Dissatisfaction Scale (BIDS), whereas Lopez-Fernandez et al. [125•] examined the body image with the Body Shape Questionnaire [127], in their online survey. Three studies [65, 119, 122] applied the Body Image Questionnaire [121].

Social, Academic, and Emotional Self-Concept

The research revealed 25 studies investigating social, academic, and emotional self-concept domains associated with gaming. The assessment of social and emotional self-concept included the evaluation of social appraisal, social anxiety, the ability to start a conversation or to establish and retain close friendships, one’s own general mood as well as emotional intelligence characteristics (emotional self-control, and the ability to recognize and express one’s own emotions).

Twenty-three of the 25 studies indicated that GD is associated with negative self-evaluation of the own academic performance [132•, 139•] as well as of social [3, 41, 51, 57•, 65, 68, 75•, 87••, 96, 101, 109, 119, 125•, 133, 135, 148••] and emotional competences [65, 85, 90, 96, 119, 141]. One of the remaining two studies observed that only male at risk gamers and not problematic gamers displayed higher social anxiety and loneliness compared with normative gamers [45]. The other study did not explicitly assess GD [103] but found that adolescent regular gamers (playing significantly more than irregular gamers) reported a better emotional regulation compared with irregular gamers. At the same time, regular gamers displayed more deficits in emotional expression and higher alexithymia compared with those with less usage.

The study research revealed one cross-sectional and five longitudinal studies of major importance. The study of Che et al. [85] assessed the relation between GD and characteristics related to the emotional self-concept (i.e., emotional intelligence) in 931 male adolescents. They reported a negative association of all emotional intelligence subscales with core symptoms and related problems of GD. However, after controlling for perceived self-efficacy and perceived helplessness, only the subscale self-management of emotions showed a direct negative effect on GD scores.

Lemmens et al. [68] observed that deficits in social competences (e.g., starting a conversation, expressing feelings to someone else, or introducing oneself to a stranger), significantly predicted GD symptoms in adolescents after 6 months. Gentile et al. [109] reported in their longitudinal study that those adolescents who developed GD after 2 years showed less social competence at baseline compared with those who never fulfilled the criteria for GD. On the other hand, the study findings of Van den Eijnden et al. [148••] revealed that GD in male adolescents negatively affects social competences 1 year later. Regarding the two longitudinal studies assessing the academic self-concept in school students, Mößle and Rehbein [132•] observed a significant effect of negative self-reported school performance on GD after 1 year in school children. Rehbein and Baier [139•] did not replicate this effect after a 5-year observation period.

Avatar Identification

The research revealed eight out of ten studies reporting a positive association between avatar identification and GD [65, 75•, 80••, 125•, 126, 129•, 143, 147]. The remaining two articles did not consider GD scores in their analyses [77, 79], but the results indicated a strong avatar identification particularly in young gamers.

Findings of one longitudinal study suggest that a close relationship with the own avatar is a high risk factor for GD scores after 2 months [80••]. You et al. [75•] observed a significant positive correlation between avatar identification and GD in adolescents. Lopez-Fernandez et al. [125•] observed that avatar identification, as well as embodied presence, defined as the degree of how connected the respondents feel to their own avatar, predicted GD in adult female gamers. Mancini et al. [129•] assessed more specifically whether the type of avatar or rather the gamers’ identification with the graphical agent, correlated stronger with GD score. They found that an utopian avatar—defined as a positive discrepancy in Big-Five personality scores between avatar and ideal self—did not directly correlate with GD but was moderated by the degree of avatar identification. Only an idealized avatar—defined as a positive discrepancy of scores between avatar and actual self—was directly associated with GD.

Neural Correlates of the Self-Concept and Avatar Identification in GD

This literature research revealed six studies, investigating neural correlates of self-concept and avatar identification in addicted and regular gamers. Three of the studies applied tools with relatively high evidential support for their psychometric properties [119, 122, 154•]. Table 3 gives an overview of the findings.

Table 3 FMRI studies on emotional, social, and physical self-concept domains and avatar identification
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Three studies focused on the assessment of the self-concept in addicted gamers. Only one study assessed the physical domain by means of a self-recognition task during fMRI in addicted and regular MMORPG-players [122]. In this paradigm, participants were presented with photos of themselves, unknown persons, and their own gaming character. No between-group differences were detected, but within-group differences revealed significant decreased activation in the left IPL (AG) during recognition of the self vs. others in the addicted group.

Kim et al. [155] investigated the self-concept with a self-referential task, asking addicted and non-addicted participants to rate self-concept-related sentences about their real self and their ideal self. Between-group comparisons revealed increased activations in the right inferior parietal lobule (IPL) during self- (vs. ideal) reflection in the addicted gamers.

A recent study on adolescents by Choi et al. [156••] assessed general, physical, and social self-concept related characteristics, by evaluating a self-referential task in addicted and non-addicted adolescent gamers. The task included three conditions: (1) thinking about oneself, (2) thinking about Admiral Sun-shin Yi (a very famous, historic Korean hero), and (3) thinking about the own avatar. Participants had to answer 20 items with yes (I agree) or no (I disagree) while being scanned. A baseline control condition was also applied, in which participants had to respond to true or false sentences (e.g., “the train is faster than the car”). Between-group analyses revealed decreased activations in the right inferior frontal gyrus during self-reflection (vs. baseline) in addicted gamers as compared with the regular gamers.

Five of the six studies assessed neural correlates of avatar identification in addicted and regular gamers [119, 122, 154•, 156••, 157••]. One of them applied a self-recognition task and four investigated the construct by means of a self-referential task. Regarding self-referential studies, three of four findings revealed higher activations in the TPJ during avatar exposure in participants with GD compared with non-addicted gamers [119, 154•, 156••]. The remaining study did not differentiate between addicted and non-addicted gamers [157] but still found increased activations in the left IPL (AG) during the reflection about the own avatar relative to self, close friends, and distant others in long-term regular MMORPG gamers. The only study investigating avatar identification by means of a self-recognition task in addicted and regular gamers did not find significant between-group differences [122].

Discussion

The aim of the current literature review was to examine the relationship between GD and self-concept, as well as avatar identification. The latter was assessed according to the self-discrepancy hypothesis, which assumes that identification with one’s own avatar might be a compensation mechanism for self-concept-related deficits [19]. The research examining self-concept in GD comprised self-esteem as well as various other subdomains of self-concept, such as body image as well as social and emotional competencies. Apart from self-report studies, we also considered fMRI investigations on neural correlates of self-concept and avatar identification in GD.

Almost all of the existing eighteen studies agreed that low self-esteem is associated with GD. These results of GD were also confirmed by longitudinal studies [68, 74••]. Two out of three studies reported that low self-esteem increased the risk for GD after 1 year and after 6 months, respectively. Regarding longer measure time points, one longitudinal study did not confirm a relation between changes in self-esteem and changes in symptom severity of gaming addiction after 2 years [40••]. However, apart from the long 2-year interval between the two assessments in this study, additional reasons for this failed association could be the following: older age of the study sample; the recruitment took place exclusively on an online gaming server; and the assessment was conducted solely via the Internet. The two longitudinal studies which concluded that GD was predicted by a low self-esteem assessed adolescents in face-to-face interviews only [68, 74••]. These aspects make it clear that a comparison between the study results should be treated with caution.

However, the findings do indicate that low self-esteem influences the development of GD in adolescents after 1 year, which raises the question of whether this also applies to adult participants. To clarify this question, further studies are needed.

Beard et al. [42] reported that a high gaming-contingent self-worth was associated with lower levels of overall self-esteem. This might indicate that an individual increasingly forms virtual self-worth by social and performance-related rewards of a game and this, in turn, might lead to enhanced usage and the development of tolerance (i.e., increasing time or frequency of gaming or spending money in games), as well as GD. Grawe [158] considered the enhancement of self-esteem as a basic human need. According to the study findings, this need seems to be violated in persons with GD and might have an influence on the development of GD after 1 year. Conclusively, it can be said that therapeutic approaches regarding GD should take the enhancement of self-esteem into account.

The literature research did not reveal many studies assessing the physical self-concept in GD. Four out of five studies reported deficits in body image to be associated with GD [65, 119, 122, 125•]. It should, however, be noted that three studies were based on very small sample sizes (65, 119, 122; naddicted gamers < 20) and one other study assessed female gamers only [125•]. One online survey did not confirm this relationship [57•]. As mentioned above, all studies assessed body image with different instruments which raises the question of how comparable and valid the results are. In conclusion, the data indicate a relationship between a negative body image and GD; however, this domain of self-concept and its influence on GD need to be further assessed and replicated for valid results.

Most studies on the emotional self-concept revealed that addicted gamers rated themselves as having more difficulties in emotional intelligence, such as recognizing and expressing own emotions as well as in emotional regulation [65, 85, 90, 96, 119, 141]. However, one study showed that gamers with higher usage showed improved emotional regulation but displayed more deficits in emotional expression and higher alexithymia as compared with those with less usage [103]. The authors concluded that gamers might improve their emotional functionality by learning coping strategies that help them to deal with problematic emotional situations. They can accomplish this with their avatar in a virtual environment, which, in turn, can then be applied to real-life situations. This could, particularly, be the case for regular but not for problematic or addicted gamers, who escape from negative feelings that arise from intra- and interpersonal problems in everyday life more and more. They increasingly fuse with the virtual world and use the game as a sort of new virtual life. Thus, it can be hypothesized that deficits in emotional competencies are associated with GD but maybe not with regular gaming. One explanation might be that addicted gamers initially have the same motives for gaming (i.e., dealing with negative emotional and social situations in a better way). However, addicted gamers might have higher psychopathology for depressive and (social) anxiety symptoms leading to social withdrawal and this, in turn, inhibits them to transfer their learned strategies into real life. Villani et al. [159] suggested this assumption in a recent review. They analyzed studies assessing the relationship between videogame playing and changes in emotional regulation abilities. Their findings revealed a curvilinear course of the relationship between gaming and mental health outcomes (i.e., moderate players demonstrated better psychosocial and mental health). They concluded that playing video games may enhance emotional intelligence and emotional regulation for regular but not for excessive problematic gamers.

According to the findings considered in our review, it can be concluded that addicted gamers have stronger deficits in emotional processing and emotional regulation compared with non-addicted gamers or non-gamers. In order to create a stable foundation for learning how to channel strong emotions in a healthy and mindful way, individuals with impaired emotional competencies need even more social attention, social support, and promotion in line with their skills and ambitions. This assumption is in accordance with related findings showing that socialization mediates between emotional competencies and the development of GD [155, 160]. Kim et al. [155] found that aggressiveness was associated with a risk of GD and this relationship was mediated by a dysfunctional and negative father-child communication style. Also, Zhang et al. [160] reported less social support to be negatively correlated with GD. Less social support might also be a result of certain difficult personality traits, such as high impulsivity or strongly introverted behavior. The former of which might lead to interpersonal conflicts, whereas the latter might hinder finding social contacts. The way the environment (e.g., family and teachers) deals with these character traits is paramount for the formation of a healthy self-concept.

Negative social feedback or exaggerated societal or familial expectations placed upon the individual, inevitably lead to higher discrepancies between the ideal self (“How should I be?”) and the real self (“Who am I?”). This, in turn, increases the risk of deficits in emotional and social competencies as well as depressive and anxiety symptoms.

Almost all studies on the social domain of the self-concept reported addicted gamers to rate themselves as more lonely and anxious to speak in front of others or to be at the center of social attention, as well as having problems with starting a conversation with a stranger [3, 41, 51, 57•, 65, 68, 75•, 87••, 96, 101, 109, 119, 125•, 133, 148••]. Apart from that, three longitudinal studies showed that deficits in social competencies were a cause (after 6 months and 2 years) as well as a predictor for GD after 1year [68, 109, 148••].

These results might give a hint that in the short term online games may effectively reduce the discrepancy between the ideal self and the real self, by enabling anonymous communication and the formation of virtual friendships as well as by conveying the feeling to be an important part of a gaming group. In the long run, however, coping with negative emotions (e.g., feelings of insufficiency) and social problems through gaming increases the risk to develop GD. The augmented escapism into a virtual world, in turn, leads to increased social withdrawal in the real world and less learning experiences in social and emotional situations. In due course, the gamer might build a virtual self-concept that is closer to the ideal self, which could make it difficult to accept the real self. This idealized virtual self-concept is acted out through the gamer’s avatar.

Accordingly, study findings on avatar identification indicate that the own avatar (and its in-game skills) compensates for self-concept deficits [65, 80••, 125•, 129•, 143, 147]. You et al. [75•] suggested self-esteem to have a significant negative correlation with avatar identification and GD. Furthermore, avatar identification mediated the relationship between GD and depression, as well as social skill deficits.

Additionally, Mancini et al. [129•] reported that solely the use of an idealized avatar (rated to be better than the real self and worse than the ideal self) is directly related to GD, as compared with using a utopian avatar (rated as being better than the ideal self). This result indicates that gamers tend to create idealized avatars, which still partly resemble their real selves.

The second aim of the review was to highlight the studies investigating neural correlates of self-concept and avatar identification in addicted gamers. The literature research revealed six studies assessing these features with self-referential and self-recognition tasks (Table 2).

Only three functional imaging studies were found, assessing underlying self-concept-related characteristics of the brain between addicted and non-addicted gamers. One of them applied a self-recognition task and did not detect any between-group differences [122]. The remaining two studies assessed underlying neural mechanisms of the self-concept in GD with self-referential tasks. However, the study findings were based on different contrasts. Choi et al. [156••] reported decreased activation in the right IFG in addicted gamers during self-reflection in contrast to a baseline condition of neutral sentences. Kim et al. [155], on the other hand, observed increased activation in the IPL during self- vs. ideal self-reflection in the addicted group. The meta-analysis of Hu et al. [24] reports that both regions are associated with self-referential processing.

Together with the angular gyrus, the IPL is a relevant part of the TPJ, which is said to be associated with ToM processing (i.e., the ability to put oneself in another person’s cognitive mindset and to make assumptions about other persons’ cognitive processes and intensions) [36, 37]. However, as mentioned above, the IPL and other ToM-associated regions, such as precuneus and the superior temporal gyrus, were also reported in the meta-analysis on self-referential processing by Hu et al. [24].

The IPL and the IFG are considered to be the main components of the mirror neuron network [161, 162]. They form the neural basis for observational learning [163] and fire in the same way during one’s own actions and while observing someone else act. Therefore, it is not too far of a stretch to argue that ToM processing—or the identification with others—plays a relevant role during self-reflection during which an individual must retrieve knowledge about their own “affective” and “cognitive” character traits vis-à-vis previous experiences. Choi et al. [156••] assessed the correlates of self-concept in GD based on the task contrast between self-reflection and a baseline condition, which showed a decrease in IFG activation in addicted gamers as compared with non-addicted gamers. This could mean that addicted gamers may have more difficulties retrieving information regarding their self-concept. On the other hand, Kim et al. [155] found an increase in IPL activation in the addicted group during self vs. ideal self-reflection. This could be the result of a closer relationship and, therefore, an increased identification with the real self, as compared with the ideal self in individuals with GD.

Three out of five fMRI studies on avatar identification (Table 2) also observed increased activation in TPJ regions, such as the IPL (e.g. AG) and the temporal pole, during avatar reflection (as compared with reflection of the real self and ideal self as well as a baseline condition) [119, 154•, 156••]. Together with the results of Kim et al. [155] on self-reflection, the neural findings might demonstrate that addicted gamers identify to a higher degree with their avatar as compared with their real self and their ideal self. However, they still might have a closer relationship to their real self as compared with their ideal self (avatar > real self > ideal self). This assumption is in accordance with the self-report findings indicating avatar identification as a predictor of GD [75•, 125•, 129•].

However, the studies included in this review present some limitations. First, most of the studies are based on cross-sectional designs. More longitudinal studies are needed to explore causal links between self-esteem, self-concept as well as avatar identification and GD. Second, male participants are often in the majority which impairs generalizability on both genders. Third, different studies used different instruments to measure the mentioned variables, which makes the results less comparable. Fourth, all neurobiological findings were based on small sample sizes (n < 20 for the control group and n < 20 for the group of addicted or pathological gamers). Fifth, only few studies applied instruments covering all DSM-5 criteria [38].

Conclusions

In sum, the current review provides the following conclusions. First, there seems to be a stable association between GD and low self-esteem, as highlighted in the majority of existing studies on this topic. Second, the specific domains of self-concept seem to be associated with GD. At closer examination, it becomes apparent that the social and emotional self-concept domains show negative relations to GD. The relationship of the academic as well as the physical self-concept appears to be less stable and warrants further research. Third, the self-report findings are mirrored in the neurobiological studies on self-concept and avatar identification.

Thus, the self-report and neurobiological findings indicate that deficits in self-concept might be compensated with a virtual idealized avatar. This is also in accordance with the “Interaction of Person-Affect-Cognition-Execution” (I-PACE) model of Internet use [164]. The authors suggest that with repeated use, initial gratification (positive reinforcement) of the specific application decreases and the compensation for negative feelings (e.g., loneliness) and cognitions (e.g., “I am nobody without the Internet”) becomes increasingly important.

The escapism of the virtual gaming world; the feeling of belonging to an important group; the formation of virtual friendships; and the identification with a mostly idealized avatar might be a fast and reward-related strategy to compensate for a negative self-concept. The positive effect that gaming has by relieving gamers from negative mood states for a short period increases the probability of repeat gaming and, therefore, the risk to develop GD. The individual increasingly fuses with the virtual world and accordingly fosters an idealized virtual self-concept that grows ever more distant from their own self-image.