To supplement the confirmatory model and data, we also conducted several exploratory analyses based on motivational theory. Providing that we could find support for the hypothesized cross-lagged model, and that it can hold over a longer time period (i.e., equilibrium assumption), the model also tests if psychological need satisfaction would serve as a mediator between IGD and health outcome ( Little et al., 2007 ). We examined this possible mechanism by directly reporting the mediation effect computed in the confirmatory model ( Fig. 1 ), but did not pre-register this hypothesis (Exploratory Analysis 1). Furthermore, consistent with SDT, we investigated the extent to which the individual basic psychological needs for competence (Exploratory Analysis 2), relatedness (Exploratory Analysis 3), and autonomy (Exploratory Analysis 4) need satisfaction serve as mediators for the linkage between IGD and health. It may be that only one need, for example, lower experiences of competence, carries effects identified with IGD symptoms. Finally, we examined the possibility that IGD symptoms, as a form of problematic gaming, may displace real-life social and physical activity ( Lanningham-Foster et al., 2006 ; Neuman, 1988 ; Sisson et al., 2010 ), and by doing so undermine health ( Cohen, 2004 ; House, Landis & Umberson, 1988 ). We tested this possibility in two alternative models that add these factors to the confirmatory model (see Fig. 2 ). On this basis we expected that these two activities might link directly to health (Exploratory Analyses 5 & 6) and mediate the relations between IGD and health (Exploratory Analyses 7 & 8).

In this study we evaluated confirmatory hypotheses (i.e., a priori and pre-registered) and conducted exploratory analyses (e.g., data and theory driven, but not pre-registered) concerned with the antecedents and consequences of Internet Gaming Disorder ( Cumming, 2012 ; Wagenmakers et al., 2012 ). By making this distinction, summarized in Table 1 , we were able to draw robust conclusions about IGD by rejecting or upholding our a priori hypotheses, and to explore theoretically important questions after the data were known ( Ioannidis, 2012 ). Our first set of confirmatory predictions concerned the temporal stability of IGD, need satisfaction, and health. We hypothesized that the observation of each factor at the start of the study would be linked to the same factor at the end of the study (Hypotheses 1–3); Testing these direct effects also served as a control for the cross-lagged paths. Building on motivational work indicating that the absence of need satisfaction leads to dysregulated behaviour, our second set of confirmatory hypotheses concerned the interrelations between psychological needs, health, and IGD. We anticipated that need support would predict fewer IGD symptoms six months later (Hypothesis 4), and we expected reciprocal effects with need satisfaction such that IGD symptoms at the start of the study would also undermine need satisfaction six months later (Hypothesis 5). Informed by the motivational literature linking psychological needs to mental, social, and physical health we anticipated that need satisfaction at the start of the study would link to health six months later (Hypothesis 6). Moreover, based on the extant literature on dysregulated gaming we expected that IGD symptoms at the start of the study would predict poorer health six months later (Hypothesis 7).

The goal of the present research was to rigorously investigate the etiology and personal outcomes of Internet Gaming Disorder and to expand what is empirically known about the health effects of this potential psychiatric disorder. To this end we conducted a prospective longitudinal study with a large and representative adult cohort informed by DSM-5 guidance ( Hasin et al., 2013 ; Kardefelt-Winther, 2014b ) and motivational theory ( Deci & Ryan, 2000 ; Ryan & Deci, 2000 ), using an approach grounded in open science methodology ( Morey et al., 2016 ).

A second central question concerning IGD has to do with its psychological consequences, the downstream effects that dysregulated gaming might have on need satisfaction and health. Based on a smaller body of work concerning needs and dysregulation, we might expect that IGD would deprive people of need satisfaction over time. In line with this prediction, we would expect a reciprocating relationship between psychological need satisfaction and IGD. Dysregulated players may experience their gaming as disruptive to the fulfillments they might otherwise experience in their daily lives. For example, pathological patterns of engagement might interfere with opportunities to experience a sense of competence by achieving desired goals in the real world, or even in the gaming world if the player feels the play to be more of a compulsion than a gratification. It is also possible that IGD could displace or interfere with other activities such as family meals, social events, and academic or workplace meetups as suggested by relations between problematic gaming and social capital ( Scharkow, Festl & Quandt, 2014 ). Although this expectation has not been tested in relation to Internet gaming per se , there is some support for this idea in that individuals who have obsessive passion indicative of dysregulation in the workplace experience less support for the three needs of autonomy, competence, and relatedness ( Forest et al., 2011 ). Indeed, it may be that those with IGD show poor health because IGD undermines their psychological needs. The literature reviewed above suggests a robust link between psychological need satisfaction and mental, physical, and psychosocial health. Insofar as IGD undermines needs, it might indirectly impact on these criteria. In line with this idea, workplace need satisfaction in the research discussed above have mediated the link between obsessive passion and mental health ( Forest et al., 2011 ; Przybylski et al., 2009 ).

More immediate to the current work, SDT research has been applied to dysregulated technology use in cross-sectional research. The absence of need satisfaction has been linked to excessive use of Facebook and other Internet use ( Sheldon, Abad & Hinsch, 2011 ; Williams et al., 2000 ), whereas its presence has been linked to Internet use that contributes to well-being ( Sheldon, Abad & Hinsch, 2011 ). Individuals who experience need satisfaction also report lower obsessive passion for videogame play ( Przybylski et al., 2009 ), as well as play indicative of more pressure and less enjoyment of the task ( Lafrenière, Verner-Filion & Vallerand, 2012 ). In sum, this body of work suggests that need satisfaction reduce the likelihood of behavioral regulation, and as such individuals who experience the satisfaction for these three psychological needs in their day-to-day lives are less likely to engage Internet gaming in a disordered and problematic manner.

Internet-based video games are a ubiquitous form of recreation pursued by the majority of adults and young people ( Duggan, 2015a ). With sales eclipsing box office receipts, games are now an integral, even inescapable, part of modern leisure ( MPAA, 2015 ; Newzoo, 2016 ). Commensurate with their popularity, concerns that games dysregulate the behavior of some have immerged ( Kardefelt-Winther, 2014b ). The widespread appeal of these virtual contexts has been of particular interest to psychologists and psychiatrists (for a review see King et al., 2013 ). In fact, the most recent revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; American Psychiatric Association, 2013 ) identifies Internet Gaming Disorder (IGD) as a possible psychiatric condition. Following this determination, the American Psychiatric Association’s (APA) Substance-Related Disorders Work Group outlined a call for rigorous research into the potential disorder’s validity, etiology, and temporal stability ( Hasin et al., 2013 ).

To evaluate the extent to which these abbreviated assessments mapped onto well-established assessments of health and motivational processes, an independent sample of 507 American adults (228 male, 273 female, 6 transgender, gender non-conforming, or other) were recruited using the Amazon Mechanical Turk platform. Ethical review was conducted by the research ethics committee at the University of Oxford and participants were compensated $1.20 to complete this brief survey which assessed our primary study measures as well as need satisfaction using the Basic Need Satisfaction and Frustration Scale ( Chen et al., 2015 ), mental health using the Warwick-Edinburgh mental well-being scale ( Clarke et al., 2011 ), social and physical health using the MOS-36 ( Sherbourne & Stewart, 1991 ; Ware & Sherbourne, 1992 ), and health-related anxiety using the HAI-18 ( Salkovskis et al., 2002 ). Linear models regressing longer measure scores onto our primary study measures indicated our brief measures of basic psychological need satisfaction ( β = .78), mental health ( β = .68), social health ( β = .50), and physical health ( β = .74) were highly correlated with the longer well-validated assessments. More importantly, results from a model regressing physical health scores ( Ware & Sherbourne, 1992 ) simultaneously onto our brief physical health measure ( β = .60) and a measure of health anxiety ( β = − .31; Salkovskis et al., 2002 ) indicated our brief assessment successfully tapped variance linked with perceptions of health.

Two single-item scales were used to measure everyday behavior ( Laganà, Bratly & Boutakidis, 2011 ; Milton, Bull & Bauman, 2011 ). Participants were asked to reflect on the past six months of their lives and rate how frequently they engaged in social activity: “Spent quality time with friends or family (e.g., playing games, picnics, or reading)” and physical activity: “Engaged in physical exercise indoors or outdoors (e.g., gym, aerobics, or sports)”, using a 5-point response scale that ranged from 1 “ Never ” to 5 “ Every day or almost every day ”.

A three-item motivation scale was used to tap into participant psychological need satisfaction, taken from the widely used Basic Psychological Needs Scale (BPNS; La Guardia et al., 2000 ). Participants were asked to reflect on the past six months and rate their experience of satisfaction for the needs for autonomy, competence, and relatedness using a 5-point response scale that ranged from 1 “ Not at all true ” to 5 “ Very true ”. Individual scores were averaged for Time 1 (α = .81, M = 3.89, SD = 0.96) and Time 2 (α = .82, M = 3.90, SD = 0.98).

Participants were asked to reflect on the past six months of their lives and rate how frequently they engaged in online gaming: “Played video/computer games online (e.g., Candy Crush, Minecraft, or Farmville),” using a 5-point response scale that ranged from 1 “ Never ” to 5 “ Every day or almost every day ”. Of those who said they engaged with Internet games, a total of 44.3% (95% CI [42.6–46.1]) said they played every day, 25.3% (95% CI [23.8–26.8]) played once or twice a week, 11.4% (95% CI [10.4–12.6]) once or twice a month, and 18.9% (95% CI [17.6–20.4]) less often at the start of the study. At the end of the study 46.5% (95% CI [44.4–48.5]) said they played everyday, 24.5% (95% CI [22.8–26.3]) played once or twice a week, 11.1% (95% CI [9.9–12.5]) once or twice a month, and 18.0% (95% CI [16.4–19.6]) reported playing less often.

Participants completed a nine-item criteria checklist drafted in consultation with clinical and research psychologists studying video games and behavioral addictions and applied in two previous investigations of IGD ( Przybylski, 2016 ; Przybylski, Weinstein & Murayama, 2017a ), and included items such as “I felt moody or anxious when unable to play”, “I felt that I should play less but couldn’t”, and “risked friends or opportunities due to games”. More than half of participants reported no criteria at the first time point (70.0%) or at follow-up (73.2%). The proportion of participants decreased as the number of criteria endorsed increased for both the first and follow-up period. Overall, participants endorsed a small number of criteria ( M = 0.56, SD = 1.13 at T1; M = 0.47, SD = 0.97 at T2). APA recommendations for clinical levels of IGD include endorsing five or more of the nine criteria ( Hasin et al., 2013 ; Petry et al., 2014 ) paired with endorsement of personal distress due to Internet gaming use ( American Psychiatric Association, 2013 ). The proportion of participants who endorsed five or more criteria was 1.49% (95% CI [1.11–2.00]) at the first time point and 0.99% (95% CI [0.65–1.51]) at follow-up, and only a very small proportion of participants endorsed the statement that they “suffered significant distress due to gaming” in the past six months, the criteria for addiction as identified in earlier research ( Przybylski, Weinstein & Murayama, 2017a ): 0.38% (95% CI [0.21–0.68]) at the first time point and 0.30% (95% CI [0.13–0.65]) at the end of the study. Interestingly, only three participants reported more than four IGD criteria at both observed time points and none of the participants who met a diagnostic threshold including distress at the start did so at the end of the study.

Ethical review for data collection and analysis was conducted by the research ethics committee at the University of Oxford (C1A15006). All participants polled for the present research were above 18 years of age and members of the YouGov American panel. Panel participants completed a double opt-in process that involved both agreeing to the YouGov Terms and Conditions ( YouGov, 2017a ) meaning they were willing to be contacted as part of participating a member of the Internet-based YouGov Omnibus panel generally, and they agreed to participate in the present study. In line with the YouGov Privacy Policy ( YouGov, 2017b ), the investigators did not have access to any uniquely identifying participant information. Participants could contact investigators using by way of email contact at YouGov. No inquiries linked to the present studies were received.

Data were collected at two time points with participants recruited through YouGov’s 1.8 million person Internet-based American panel. Following an approach used in previous behavioral health research (e.g., Cranwell, Opazo-Breton & Britton, 2016 ; Reeves et al., 2013 ) panelists were selected at random from the panel using quotas informed by 2010 U.S. Census data and pre-captured information about panelists’ age, gender, ethnicity, and geographic region. Fieldwork was conducted between October 2015 and March 2016. From this, a nationally representative sample of 5,777 adults aged 18 years and older from the United States completed the initial assessment as part of an ongoing project studying Internet Gaming Disorder (see: Przybylski, Weinstein & Murayama, 2017a ) and a total of 4,594 completed the follow-up measures six months later. Consistent with our earlier IGD research ( Przybylski, Weinstein & Murayama, 2017a ), we focused on participants who recently played Internet games at the time of assessments, a total of 2,316 individual (885 males and 1,431 females) played Internet games at both time points. This subsample ranged in age from 19 to 91 years ( M = 49.21, SD = 1.32), of which 1,689 (72.9%) identified as White, 246 (10.6%) as Black, 184 (7.9%) as Hispanic, 69 (3.0%) as Asian, 21 (0.9%) as Native American, 3 (0.2%) as Middle Eastern, and 101 (4.4%) as mixed race or another identification. In terms of educational attainment, 75 (3.2%) had not completed secondary school, 659 (28.5%) completed secondary school, 598 (25.8%) completed some college, 257 (11.1%) completed a two-year degree, 504 (21.8%) completed a four-year degree, and 223 (9.6%) completed a post graduate degree. Estimates of total annual household income were provided by 2,316 participants, these ranged from less than $10,000 (6.3%) more than $500,000 a year (0.2%) with most (77%) reporting between $10,000 and $150,000. The distributions of participants were broadly similar to those of videogame players, who tend to be equally divided among men and women and whose average age, including players under the age of 18 years, is 35 years ( Duggan, 2015b ), yet females were somewhat overrepresented at 60.8% in the final sample.

IGD may displace real-life social and physical activity, and by doing undermine health directly ( Sisson et al., 2010 ) or indirectly by relating to need satisfaction ( Mellor et al., 2008 ; Ng et al., 2012 ; Wilson et al., 2003 ). Given this, the mediating effects of psychological need satisfaction might be apparent because need satisfaction correlates with social activity, and these activities provide a better account for the harmful effects of IGD on health than do needs. To test this alternative explanation, we evaluated two additional cross-lagged models that included either social or physical activity (see Fig. 2 ; Exploratory analyses 5 & 6). Results showed social ( β = 0.42, p < .01) and physical ( β = .62, p < .01) activity were consistent over time and supported our expectations that physical activity at Time 1 would be associated with later health ( β = 0.07, p < .001), although social activity at Time 1 did not relate to health at Time 2 ( β = 0.02, p = .21). Contrary to our expectations (Exploratory analyses 7 & 8), those who exhibited more IGD symptoms at Time 1 did not report different levels of social ( β = 0.01, p = .68), or physical ( β = 0.02, p = .12) activity at Time 2. Thus, we did not find support for indirect effects through these activities. Moreover, links identified between IGD at Time 1 and needs at Time 2, and between needs at Time 1 and health at Time 2 (the two links suggesting the presence of an indirect effect), were significant controlling for activity levels (for the link between IGD and need satisfaction, controlling for physical activity; β = − 0.06, p < .001, controlling for social activity; β = − 0.06, p < .001; for the link between need satisfaction and health, controlling for physical activity; β = 0.09, p < .001; controlling for social activity; β = 0.07, p < .001). This constellation of results suggests that the effects of IGD on social or physical activities do not provide a compelling alternative account of why IGD undermines health over time to that offered by need satisfaction.

The cross-lagged modelling approach used to test the confirmatory hypotheses also provided evidence regarding the indirect effects of IGD and health ( Little et al., 2007 ; see for an application, Bishop et al., 2011 ). If a model provides evidence for the effects of IGD on basic psychological needs, and for the effects of basic psychological needs on health, this supports an equilibrium assumption (i.e., that the same relationship holds beyond the two time points we assessed). As such, we can infer that IGD has indirect effects on health by its impact on basic psychological needs. Results provided clear evidence that IGD was indirectly linked to health through the support for basic psychological needs (see Table 2 ; Exploratory Analyses 1–4). All three further cross-lagged mediation models evaluating competence, relatedness, and autonomy separately exhibited significant mediation effects ( Table 2 ). Taken together, these results suggest each of the three needs has a mediating effect.

Using our IGD measure, participants reported few IGD criteria ( M = 0.47 at T2, out of 9 criteria). Although we employed a robust estimation method to account for non-normality, responses to this scale may not be best described as a normal distribution. To address the issue, we conducted negative binomial regression analysis predicting T2 IGD from T1 IGD, T1 need satisfaction, and T1 health (all the independent variables were standardized) to directly take into account the discrete count nature of the data with low occurrence rate (the part of our model that is susceptible to this issue is depicted in Fig. 1 ). The results were entirely consistent with the SEM results ( B T1IGD = .65, p < .01; B T1Health = − 0.06, p = .20; B T1Needs = − 0.20, p < .01), indicating findings were robust.

Findings from the causal model confirmed our hypothesis regarding the temporal stability of health ( β = .72, p < .001; Hypothesis 3) and the positive contribution of basic psychological need satisfaction to subsequent health ( β = .07, p < .001; Hypothesis 6). Contrary to what was hypothesized (Hypothesis 7), IGD at the start of the study ( β = .01, p = .66) did not predict lower levels of health at follow-up. This unexpected result provided evidence that there is no direct effect of dysregulated Internet gaming on adult health over time.

Results from the planned cross-lagged analysis ( Fig. 1 ) supported the hypotheses that need satisfaction at the start of the study would be positively predictive ( β = .56, p < .001; Hypothesis 2), whereas IGD would negatively influence ( β = − .06, p < .001; Hypothesis 5) need satisfaction. Though the effects observed were small they were consistent with our hypothesis suggesting that IGD could be disruptive to this form of psychological functioning. Though it was not hypothesized, the model also indicated health at the start of the study was associated with later standing on need satisfaction ( β = .17, p < .001).

We tested our expectation that IGD at follow-up would be predicted by standing at the start of the study in two ways. Results from phi coefficient analyses indicated that IGD appeared stable on a criterion level, coefficients ranged from a low of r = 0.18, for experiences of withdrawal when Internet games were not played, to r = 0.31, for using Internet games as an escape from negative mood. Results from cross-lagged analyses (see Fig. 1 ) confirmed the hypotheses that IGD at the start of the study ( β = .42, p < .001; Hypothesis 1), and basic need satisfaction ( β = − .08, p < .001; Hypothesis 4) were causally related to IGD at follow-up. The model also indicated health at the start of the study was not associated with later standing on IGD ( β = − .01, p = .74).

All the analyses were conducted with structural equation modelling using Lavaan ( Rosseel, 2012 ). In the current sample, participants who dropped out and those who stayed have different average IGD scores, M = 0.71, SD = 1.13 and M = 0.50, SD = 1.04, respectively, t (3,144) = 4.43, p < .01. To account for this attrition bias, we used full-information maximum-likelihood method to estimate parameters. This method allow us to account for attribution bias in estimating parameters by including the variables that are correlated with T2 attrition in the analysis (e.g., T1 IGD). (e.g., T1 IGD) ( Jeličić, Phelps & Lerner, 2009 ). All the models we analyzed were saturated (i.e., degree of freedom was zero). To account for this attrition bias, the full information maximum likelihood estimator was implemented in the lavaan package. Analyses were also conducted controlling for participant age and gender, and the results were consistent with those reported below. Linear coefficients, beta values, reported below reflect standardized units of change in the outcome variable as a function of one unit of change in the predictor variable.

There was one noteworthy deviation from the registered analysis plan which concerned examining IGD diagnoses in line with DSM-5 guidance ( Hasin et al., 2013 ) and previous research on IGD ( Przybylski, Weinstein & Murayama, 2017a ). Contrary to expectations, none of the participants who met the diagnostic threshold, that is, endorsed five or more items and experienced distress as a result of their game use at the start of the study also did so at follow-up. This unexpected result suggests formal diagnoses might not be stable over time. Our analyses therefore only present the alternative, also preregistered, approach for operationalizing IGD; that is, summing the number of endorsed criteria.

Discussion

Internet-based games are among the most popular forms of human recreation and empirical research is still needed to understand possible psychopathology related to their use. The present research rigorously investigated the etiology and outcomes of Internet Gaming Disorder and the findings derived from this prospective study inform our understanding of how this phenomenon is linked to dysregulation and health. Guided by an open science approach, results confirmed a number of our preregistered hypotheses concerning dysregulated online play.

In line with predictions we found that the IGD criteria proposed in the DSM-5 (American Psychiatric Association, 2013) were, on an individual and continuous basis, moderately stable over a six month period. Contrary to what we expected, however, none of the participants meeting diagnostic thresholds at the start did so at the end of the study, and only three participants reported more than four IGD criteria at the start and six months later. These findings, that very few, if any, individuals who meet the proposed diagnostic thresholds over time mirror those derived from other large-scale representative studies of problematic gaming research (Festl, Scharkow & Quandt, 2013; Scharkow, Festl & Quandt, 2014). These unexpected results do not support a theoretical framing of Internet Gaming Disorder as a chronic psychiatric condition akin to substance abuse disorder as some have argued (e.g., Hasin et al., 2013; Petry et al., 2014); rather, the constellation of results we uncovered provide evidence that dysregulated gaming is a nuanced phenomenon that requires careful conceptualisation, and one which can be fruitfully studied from a motivational perspective (Deci & Ryan, 2000; Griffiths et al., 2016; Kardefelt-Winther, 2014b). These results may also speak to the nature of the proposed disorder. For example, they mirror some research on problematic gambling, another kind of behavioural dysregulation, which shows such difficulties are more episodic than continuous (Slutske, Jackson & Sher, 2003), though it is unclear whether these IGD episodes are chronic across a span of multiple years, similar to models of addiction where the individual is never truly free of the illness but only experiences intermittent expressions of it (Saitz et al., 2008), possibly as an expression of maladaptive coping (Kardefelt-Winther, 2014a). With this in mind, further research investigating the nature of IGD as chronic or episodic would be useful. Generally, IGD has been measured in terms of its more or less frequent occurrence across a period of 12 months (Pontes et al., 2014), but a lack of stability in clinical thresholds being met across a six-month period suggest that these symptoms would need to be frequently reoccurring over a 12-month period for them to be captured by these longer-term assessments.

Also contrary to our expectations, we did not find that IGD had an observable direct effect on health over time. Although this finding is inconsistent with some results derived from small-scale convenience samples, it is in line with the only other representative longitudinal work which suggests mixed or non-significant lagged effects linking problematic gaming with life satisfaction and perceived success of gamers (Scharkow, Festl & Quandt, 2014). This negative finding is especially noteworthy because it indicates that IGD may not, on its own, be robustly associated with important clinical outcomes. As such, it may be premature to invest in management of IGD using the same kinds of approaches taken in response to substance-based addiction disorders, for example with TMS (Meng et al., 2014; Shen et al., 2016; Terraneo et al., 2016). Further, this pattern of findings suggests that more high-quality evidence regarding clinical and behavioral effects is needed before concluding this is a legitimate candidate for inclusion in future revisions of the DSM-5.

Despite the absence of a direct link with health, additional research findings indicated there is reason for concern when individuals exhibit IGD symptoms. Informed by the human motivation and self-regulation literature on psychological needs (Ryan & Deci, 2000), we predicted and found that those who were not psychologically need satisfied were more likely to evidence symptoms of IGD at a later time. Though the observed relations were not large in magnitude, they suggested that IGD symptoms can emerge from dysregulating environments or dysregulated psychological states brought on by the absence of psychological need satisfaction, in line with other symptoms indicative of psychopathology, such as depression and anxiety (Deci et al., 2001; Talley et al., 2010; Wei et al., 2005), disordered eating (Bartholomew et al., 2011), and borderline personality disorder (Ryan, 2005).

In line with this idea and the research reviewed above, it may also be that endorsing IGD criteria may be characteristic of a broader and more pervasive problem with self-regulation. Indeed, work with individuals who exhibit gambling disorder, the only non-substance related addiction which is recognized in the DSM-5, shows a lifetime prevalence rate of 61% for mood disorders, 75% for alcohol use, and 48% for drug use, rates higher than in the general population and which reflect a history of dysregulation (D. C. Hodgins, Peden & Cassidy, 2005). Given we did not test comorbidity with other clinical disorders, or lifetime prevalence of other clinical disorders in those who exhibit IGD symptoms, future research doing so would greatly enhance our understanding of the nature of the disorder and its treatment.

As expected, we found small yet consistent reciprocal relations existing with needs, such that those who exhibited symptoms of IGD were less likely to be need satisfied later. This observed pattern of joint causality between needs and IGD suggests that the dynamics underlying unhealthy behaviors mirror those observed in other life contexts (Forest et al., 2011). In addition, the confirmation of this hypothesis indicates that dysregulated gaming may be detrimental to experiencing psychological need satisfaction through other avenues and may crowd out more psychologically edifying pursuits (Chen et al., 2015); for example, IGD symptoms may directly interfere with pursuing other meaningful life goals that satisfy needs (Niemiec, Ryan & Deci, 2009). Alternatively or in addition to this, the experience of compulsion and obsession may directly leave individuals feeling that they have less choice, more isolated and lonely, and ineffective (Lalande et al., 2015).

Our data were collected from two time points but with a certain reasonable assumption, we can infer potential mediational process from the cross-lagged model that we tested (Little et al., 2007). Indeed, findings from the prespecified model suggested that need satisfaction mediated the effects of IGD symptoms on health; that is, the results indicated that IGD decreases health through lowering need satisfaction. In other work, such need satisfaction have been shown to relate to the health criteria we have tested in this study; that is, better mental health (Ryan & Deci, 2001), better physical health (Reinboth, Duda & Ntoumanis, 2004; Sheldon, Ryan & Reis, 1996; Thompson & Prottas, 2006), and better psychosocial functioning (H. S. Hodgins, Koestner & Duncan, 1996; Moller & Deci, 2010; Patrick et al., 2007; Weinstein, Hodgins & Ostvik-White, 2011). The current work extends this literature by suggesting that such costs to health are accrued when dysregulating or pathological behaviors undermine need satisfaction. Further, it informs the IGD and the behavioral addiction literatures by highlighting that IGD symptoms lead to lower health partly because they undermine need satisfaction.

Interestingly, in exploratory analyses we found that all three psychological needs served to link IGD to health. Although the three needs are often tested in sum (e.g., La Guardia et al., 2000), additional information can be gained by evaluating their separate impacts on wellness (Sheldon, Ryan & Reis, 1996; Weinstein & Ryan, 2010), and they have been shown to differentially affect psychological outcomes in certain contexts (e.g., Legate et al., 2013). Evidence that each has a direct effect excludes the possibility that, as an example, IGD induces a feeling of loneliness (absence of relatedness need) that is so robust it carries results using the full measure of need satisfaction.

Our final two models assessed whether social and physical activity accounted for the link between IGD symptoms and health, an especially important test given these activities may have been responsible for the indirect effects through psychological needs observed in earlier analyses. The data did not support this conclusion, and instead showed none of the expected relations between IGD symptoms and later costs to social and exercise behaviours. These findings are in line with a mixed literature in this area (Boone et al., 2007), including descriptive research which identifies that 83% of adolescents feel more connected to their friends through their technology use, and suggesting that 68% say they have received social support using technology in tough or challenging times (Lenhart, 2015). It is also consistent with findings that gaming can at times promote physical activity (Lanningham-Foster et al., 2006), and work which fails to identify a consistent relation between gaming and physical activity (Kremer et al., 2014; Mentzoni et al., 2011). In this study, we found that dysregulated gaming did not result in actual social isolation or physical inactivity, and that the subjective experience of psychological need satisfaction continues to link IGD to health even controlling for these activities. Yet it might be that IGD symptoms interfere with other meaningful activities not tested in this research that might undermine need satisfaction and provide a more direct account of why IGD undermines health. For example, as discussed above IGD may interfere with the pursuit of meaningful goals, or with academic or work responsibilities. In future work, researchers may test the possibility that engagement in other daily activities might provide a better account than physical or social activity.

It is important to note that much of the existing literature on IGD has relied on convenience samples of young adult volunteers drawn from online gaming forums (e.g., Pontes et al., 2014). This approach that differs markedly from studying the phenomenon in a representative sample of adults of all ages. Though the former approach presents serious challenges for generalisability and the two populations may be different in terms of how they cope with daily experiences (e.g., Compas et al., 2001; Garnefski et al., 2002), we expect that the mechanisms which we have examined here—namely basic psychological needs to have similar explanatory power in both. This is in no small part because nearly 40 years of SDT research has studied the impact of need satisfaction in diverse populations and across developmental stages in non-digital contexts. Indeed, psychological needs are shown to be comparably important in terms of both self-regulation and coping for children, adolescents, and adults (see review in Ryan & Deci, 2017).