Abstract
The study aimed to examine the longitudinal causal relationships of depressive moods, problematic mobile phone use, and negative school outcomes based on the cognitive-behavioral model among Korean adolescents. The changes within each construct over time were also explored. A total of 1,610 valid responses from three-year longitudinal data from the Korean Children and Youth Panel Survey were analysed and multivariate latent growth modeling was used. Depressive moods, problematic mobile phone use, and negative school outcomes at earlier ages each increased in severity across the three years. Initial levels of depressive moods increased initial levels of problematic mobile phone use and negative school outcomes, including changed rates of negative school outcomes. Additionally, changed rates of depressive moods positively predicted changed rates of problematic mobile phone use and negative school outcomes. Lastly, initial levels and changed rates of problematic mobile phone use predicted initial levels and changed rates of negative school outcomes respectively. Implications of the findings in the context of adolescents' psychological problems and problematic mobile phone use are discussed.
Keywords
Problematic mobile phone use (PMU) has become common among adolescents. A Korean national survey in 2016 showed that 30.6% of teenagers were dependent users of mobile phones and had experienced adverse consequences due to excessive use of and loss of control over cell phones. The ratio of dependent users among teenagers, 30.6%, was much higher than that of adults: 19% of people in their 20s, 13.3% of those in their 30s, and 11.8% of those in their 40s (Ministry of Science, ICT and Future Planning of Korea & National Information Society Agency of Korea, 2017). The problem is that PMU is related to many adverse effects in their lives including health problems, delinquencies, and psychological and behavioral problems (Hardell, 2017; Livingstone & Smith, 2014; Vernon, Modecki, & Barber, 2018).
In particular, depressive moods are salient predictors of PMU (Bickham, Hswen, & Rich, 2015; Jun, 2016), which ultimately results in adverse school outcomes (Sánchez-Martínez & Otero, 2009). Prior studies have shown that depressive symptoms of teenage students increase PMU (Augner & Hacker, 2012; Ge, 2014; Kim, Seo, & David, 2015) and maladaptive school outcomes (Fröjd, Nissinen, Pelkonen, Marttunen, Koivisto, & Kaltiala-Heino, 2008; McCarthy, Young, Benas, & Gallop, 2018). PMU increases negative school outcomes as well (Egger, Costello, & Angold, 2003; Owens, Stevenson, Hadwin, & Norgate, 2012). More generally, depressive feelings are often precursors to unhealthy and unsuccessful development among adolescents (Webb, Panico, Bécares, McMunn, Kelly, & Sacker, 2017), and adverse school outcomes are typical problems among teenage students (Werner-Seidler, Perry, Calear, Newby, & Christensen, 2017).
On the basis of previous findings, this study proposed causal relationships among depressive feelings, PMU, and negative school outcomes. However, few studies have attempted to reveal the unified relationships among the constructs based on a theoretical model. Therefore, it is necessary to use a theoretical model that allows understanding of the causes and consequences of PMU. Thus, we applied the cognitive-behavioral model of problematic Internet use (PIU) (Caplan, 2002; Davis, 2001) to PMU. According to Davis's early work (2001), the cognitive-behavioral model of PIU suggests that individuals with psychopathological problems are likely to experience cognitive and behavioral symptoms of PIU, leading to adverse outcomes. Subsequent studies from Caplan (2003, 2005) demonstrated that social skill deficit and preference for online social interactions, rather than face-to-face interactions, increases PIU, which results in troubles at work, school or in the family. Caplan (2010) demonstrated that a preference for online social interaction and mood regulation predicts the increase of deficient self-regulation, which leads to adverse outcomes. For example, individuals with severe psychological distress including depression or anxiety are likely to experience symptoms of PIU (Caplan & High, 2011), resulting in difficulties in individuals' management of their own lives (Kim, LaRose, & Peng, 2009).
Concerning teenagers, Gámez-Guadix, Villa-Georg, and Calvete (2012) confirmed the cognitive-behavioral model of PIU among Mexican adolescents and indicated that the preference for online social interaction caused by depression and anxiety increased PIU, which, consequentially, was significantly influenced adverse life outcomes. A longitudinal study among Spanish teenagers demonstrated that deficient self-regulation at T1 positively affected negative consequences of the Internet and problematic alcohol use at T2, six months apart (Gámez-Guadix, Calvete, & Hayas, 2015).
PMU, similar to PIU, is a type of technology addiction that is representative of modern society. Griffiths (1999) introduced technology addiction as a concept of behavioral addiction rather than the concept of pathological addiction including alcoholism and drug addiction. Subsequent studies have defined PMU as an obsession with mobile phones, including withdrawal symptoms and a decreased tolerance for daily life upon separation, due to mobile phone overuse and dependence (Bianchi & Phillips, 2005; Jun, 2014). Thus, like PIU, PMU involves cognitive and behavioral disorders, and by testing a mediating effect of PMU on depressive moods and negative school outcomes based on the cognitive-behavioral model, the associations among etiology, development, and consequences of PMU are expected to be revealed.
In addition, the current study explored the longitudinal causal associations of the constructs among Korean adolescents to reveal teenagers' growth over time. A few previous studies identified that each occurrence of depressive moods, PMU, and maladaptive school outcomes increase the seriousness of future conditions over time (Bowen, Jenson, & Clark, 2004; Jun, 2014, 2016; Rushton, Forcier, & Schectman, 2002). However, to our knowledge, there are no longitudinal studies that analyse the relationships among depressive moods, PMU, and negative school outcomes based on a theoretical model.
This study aimed to test the longitudinal effects of depressive moods on PMU and negative school outcomes among Korean adolescents based on the cognitive-behavioral model. For example, we proposed causal associations between initial levels and changed rates of depressive feelings and those of PMU over time. We also added a novel path, from depressive moods to negative school outcomes, to the cognitive-behavioral model, to test if PMU mediates depressive feelings and adverse school outcomes partially or fully. Prior to testing longitudinal relationships among the constructs, the study explored the changes within each construct, namely depressive feelings, PMU, and negative school outcomes over time. In this context, Gámez-Guadix and his colleagues (2015) identified the temporal and reciprocal relations between PIU and negative consequences among Spanish teenagers and Jun (2015) showed that PMU and depressive symptoms of Korean adolescents became continuously worsened over time and they had bidirectional relationships across the three years. Based on previous studies, this study developed two hypotheses: (a) depressive moods, PMU, and negative school outcomes at an earlier time positively predicts an increase in the respective construct at a later time; and (b) depressive moods increase PMU and negative school outcomes, and PMU increases negative school outcomes over time among adolescents.
Methods
Participants and procedure
The current study used three-year longitudinal data from the Korean Children and Youth Panel Survey (KCYPS). The KCYPS was established in 2010 and is conducted every year by the National Youth Policy Institute (NYPI) in Korea. The NYPI is the only national youth research institute in Korea and provides primary statistical data for youth research and policies through comprehensive panel surveys. The KCYPS used stratified multistage cluster sampling based on 2009 school statistics collected by the Ministry of Education in Korea. Participants responded to surveys conducted by experienced interviewers at their homes in the context of parental prior written consent. The initial number of participants in 2010 was 2,378, and the surveys were conducted annually with the same sample without sample substitution. We used data from the third (2012; T1), fourth (2013; T2), and fifth (2014; T3) years of the KCYPS and the number of participants per year was 2,219 in 2012, 2,092 in 2013, and 2,070 in 2014. Only participants who had used mobile phones successively during the three years, from 2012–2014, were included in the current study and there were no other inclusion or exclusion criteria. Finally, data from a total of 1,610 adolescents (790 girls and 820 boys) were used. The participants were sixth graders in 2012, and their average age was 11.94 years (SD = 0.25).
Measures
In this study, the scales used in KCYPS were used at all-time points. Participants responded to questionnaires through face-to-face interview surveys. All questionnaire items of the primary variables used in this study are as follows.
Depressive moods
Depressive moods were measured by coding the three items established by Kim, Lim, Kim, Park, Yoo, Choi, and Lee (2006), as used in the KCYPS: ‘I am not happy to be alive’, ‘I have many worries’, and ‘I think my life is depressing’. Each item was rated on a scale from 1 (never true) to 4 (always true). The Cronbach's alpha coefficients were 0.860 at T1, 0.839 at T2, and 0.813 at T3.
Problematic mobile phone use
PMU was measured using the seven items established by Lee, Kim, Nah, Lee, Kim, and Bae (2002), as used in the KCYPS: ‘I am worried when I do not hear from anybody on my mobile phone’, ‘I cannot stand being bored without a mobile phone when I am alone’, ‘I am using my mobile phone more often’, ‘I feel nervous without a mobile phone when I go out’, ‘I feel isolated when I do not have a mobile phone’, ‘I do not notice how time flies when I am using a mobile phone’, and ‘I cannot live without a mobile phone’. Each item was rated on a scale from 1 (never true) to 4 (always true). The Cronbach's alpha coefficients were 0.890 at T1, 0.893 at T2, and 0.881 at T3.
Negative school outcomes
This study measured negative school outcomes by coding the four items established by Min (1991) with reference to the school adjustment scales of Yoon and Moon (1977) and Lee (1990), as used in the KCYPS: ‘I do not like school classes’, ‘I do not complete my homework’, ‘I do not understand what I learned in classes’, and ‘I do not ask teachers or friends when I do not understand’ These items were rated on a scale of 1 (never true) to 4 (always true). The Cronbach's alpha coefficients for these items were 0.745 at T1, 0.799 at T2, and 0.793 at T3.
Statistical analysis
To examine the changes over time in depressive moods, PMU, and maladaptive school outcomes as well as the longitudinal associations among the three constructs, multivariate latent growth modeling was performed in this study. Latent growth modeling (LGM) is an advanced statistical method conceptualized by the structural equation modeling framework, and analyses univariate trajectories of longitudinal variables, which means the changes within individuals over time, and associations of changes in single or multiple longitudinal variables (Duncan & Duncan, 2009; Muniz-Terrera, Robitaille, Kelly, Johansson, Hofer, & Piccinin, 2017). LGM estimates means of latent variables consisting of an intercept and a slope and path coefficients between constructs: An intercept describes the mean of a construct at the initial time, and a slope illustrates the changed rate of the mean of a construct over time (Duncan, Duncan, Strycker, Li, & Alport, 1999). Multivariate LGM can test how a change in one longitudinal variable influences the change in other longitudinal variables and provides a dynamic view of the associations between changes in multiple processes (Duncan, Duncan, & Strycker, 2001). In multivariate LGM, modeling of intercept-intercept, intercept-slope, and slope-slope associations between constructs is examined (Kim, Kim, & Hong, 2007). Overall, the path-diagram of our multivariate LGM is represented in Figure 1. AMOS ver. 20.0 was used to perform multivariate LGM.
Multivariate latent growth model.
Results
Model fit indices of measurement invariance models.
Note: DM represents depressive moods; PMU represents problematic mobile phone use; NSO represents negative school outcomes. All χ2 values were significant at p < .001.
The mean values of all main variables at T1, T2, and T3 showed values of around 2 points of 4 points: Depressive moods (M = 1.78, 1.86, 1.96; SD = 0.67, 0.63, 0.59), PMU (M = 2.06, 2.26, 2.28; SD = 0.71, 0.70, 0.66), and negative school outcomes (M = 2.01, 2.07, 2.10; SD = 0.56, 0.60, 0.56).
In advance of fitting a multivariate LGM, we fit the single-construct LGMs for depressive moods, PMU, and negative school outcomes respectively, and we examined linear changes of the constructs over time. First, the single-construct LGM for depressive moods fit the data well: χ2 = 10.769 (df = 3, p < .05), CFI = 0.991, TLI = 0.991, RMSEA = 0.040. The means of intercept and slope were positively significant (Mi = 1.773, SEi = 0.016, p < 0.001; Ms = 0.093, SEs = 0.009, p < 0.001). It showed the initial levels of respondents' depressive moods were between low and moderate, and there was an increase in depressive mood levels over time. Additionally, there were significant variances in both intercept and slope (Vi = 0.246, SEi = 0.016, p < 0.001; Vs = 0.023, SEs = 0.006, p < 0.001), revealing individual differences in initial levels as well as changes in depressive moods across time.
Next, the single-construct LGM for PMU had an acceptable model fit, χ2 = 63.426 (df = 3, p < 0.001), CFI = 0.920, TLI = 0.920, RMSEA = 0.082. The average intercept and slope for PMU were positively significant (Mi = 2.094, SEi = 0.017, p < 0.001; Ms = 0.104, SEs = 0.010, p < 0.001). The findings indicated that the initial levels of participants' PMU were between moderate and high, and the levels of PMU have increased over time. The variance of intercept was significant (Vi = 0.227, SEi = 0.018, p < 0.001), but the variance of slope was not significant (Vs = 0.012, SEs = 0.007, p > 0.05). These findings showed that there were individual differences in initial levels of PMU, but not in changes in PMU across time. Lastly, the single-construct LGM for negative school outcomes fit the data well, χ2 = 27.184 (df = 3, p < 0.001), CFI = 0.970, TLI = 0.970, RMSEA = 0.061. We found positively significant means of intercept and slope (Mi = 2.019, SEi = 0.014, p < 0.001; Ms = 0.044, SEs = 0.008, p < 0.001). These results demonstrated that the levels of participants' negative school outcomes were between moderate and high in the beginning, and their levels of negative school outcomes increased across time. The variance of intercept was significant (Vi = 0.227, SEi = 0.018, p < 0.001), but the variance of slope was not significant (Vs = 0.012, SEs = 0.007, p > 0.05). The findings showed that there were individual differences in initial levels of negative school outcomes, but no individual differences in the change in negative school outcomes over time.
Based on the cognitive-behavioral model, this study fit a model including depressive moods, PMU, and negative school outcomes and modeled paths between the intercepts and slopes of the constructs as shown in Figure 1. The study demonstrated standardized coefficients as well as bootstrapped 95% confidence intervals based on 2,000 iterations. To decide a final approved model of this study, we compared the fits of two models: Model 1, with a direct path from depressive moods to negative school outcomes, and Model 2, without the direct path between them. We found that Model 1 had better fit indices (χ2 = 225.707, df = 23, TLI = 0.931, CFI = 0.937, RMSEA = 0.074) than Model 2 (χ2 = 421.941, df = 26, NFI = 0.871, TLI = 0.830, CFI = 0.878, RMSEA = 0.097) and the difference of χ2 was statistically significant (Δχ2 = 196.234, Δdf = 3. P < 0.001). Thus, the study selected Model 1 as the final approved model of the study shown in Figure 1.
Structural path coefficients in the final approved model.
*p < 0.05; ***p < 0.001.
Regarding the paths between intercepts and slopes, the intercept of depressive moods positively influenced the slope of negative school outcomes, β = 0.126, p < 0.05. Thus, negative school outcomes of participants with high levels of depressive moods initially increased further over time. The paths that were depressive moods intercept → PMU slope, and PMU intercept → negative school outcomes slope, were not statistically significant.
Concerning the paths among slopes, the slope of depressive moods positively influenced the slope of PMU (β = 0.349, p < 0.001), and PMU positively influenced the slope of negative school outcomes (β = 0.253, p < 0.05). The findings showed that participants who experienced increased depressive moods over time increased their PMU more over time to deepen negative school outcomes more over time, supporting the cognitive-behavioral model from a longitudinal perspective. Additionally, the slope of depressive moods positively affected the slope of negative school outcomes (β = 0.502, p < 0.001), indicating that PMU partially mediated the change in depressive moods and negative school outcomes.
Standardized estimates of the direct, indirect, and total effects of depressive moods on negative school outcomes.
*p < 0.05; **p < 0.01; ***p < 0.001.
Discussion
The present study examined the longitudinal causal relationships among depressive moods, PMU, and negative school outcomes based on the cognitive-behavioral model. We adopted the longitudinal data of 1,610 Korean students over three years and used multivariate latent growth modeling. The study indicated linear changes in depressive moods, PMU, and negative school outcomes, finding associations between the initial levels and changed rates of the constructs across the three years.
The findings showed that depressive feelings, PMU, and negative school outcomes increased persistently across the three years. These results support the previous studies showing that depressive moods (Rushton et al., 2002), PMU (Jun, 2014, 2016), and negative school outcomes (Bowen et al., 2004) worsen over time. In particular, PMU increased more in middle school students (seventh and eighth graders) than in elementary school students (sixth graders) due to mental vulnerabilities and excessive academic stress in Korea (Kim, 2012). The initial levels of PMU and negative school outcomes were between moderate and high, and there were no individual differences in changes in PMU and negative school outcomes over time. This means that most students are likely to experience PMU and negative school outcomes, and the levels of PMU and negative school outcomes, regardless of their initial levels, increase after entering middle school. Therefore, PMU and negative school outcomes should be regarded as prevalent problems for teenage students. Supervision of cell phone use and school lives is needed in families and schools for all adolescents, not just for some, to protect them from increases in PMU and negative school outcomes. Additionally, individual differences in the initial levels of depressive moods and changes over time were found in the respondents whose depressive mood levels were between low and moderate. These results suggest that some teenage students are more vulnerable to depressive feelings than others. Thus, it is necessary to identify the characteristics of the vulnerable teenagers and why they feel more depressive moods than others. Also, there is a need for particularly intensive attention and care for them, beyond what is offered to the youth in general.
It was shown that depressive moods positively predicted PMU, and PMU positively predicted negative school outcomes. Additionally, the study verified that the changed rates of depressive moods increased those of PMU, which led to an increase in the changed rates of negative school outcomes. Thus, it is important to focus on teenagers whose levels of depressive moods and PMU are rapidly increasing, even if their current levels are not high. These results resemble the prior studies illustrating causes, depressive symptoms (Bickham et al., 2015; Jun, 2016; Webb et al., 2017) and consequences, including maladaptive school outcomes (Sánchez-Martínez & Otero, 2009), of PMU. Also, these findings were in accordance with the cognitive-behavioral model among teenagers, which identified the positive relations among psychological distress, PIU, and troubles at school and family (Gámez-Guadix et al., 2012; Gámez-Guadix et al., 2015). According to the results of the study and the cognitive-behavioral theory, the more teenagers feel depressed, the more they interact with others in the virtual world using the Internet and mobile phones, which disturbs their daily lives.
This study revealed that depressive feelings directly increased adverse school outcomes and PMU partially mediated between depressive moods and negative school outcomes, which have not been verified in previous studies on the cognitive-behavioral model (Davis, 2001; Caplan, 2002, 2003, 2005, 2010). In order to reduce negative school outcomes, parents and teachers should make efforts to relieve not only PMU but also depressive feelings. Particularly, the direct paths from depressive feelings to negative school outcomes, in the initial levels and the changed rates, were significant, as mentioned above, and the direct effect of depressive moods on adverse school outcomes was bigger than the indirect effect through PMU. Thus, it is most urgent and essential for students to alleviate depressive feelings.
The study has several limitations. First, this study used longitudinal data for early teenagers aged between 12- and 14-years-old and found stable changes in depressive moods, PMU, and negative school outcomes. However, we did not explore data for adolescents of other ages such as high school students. Because the Korean national survey showed that the levels of PMU of high school students were different from those of middle school students (Ministry of Science, ICT, and Future Planning of Korea & National Information Society Agency of Korea, 2017), we suggest that follow-up studies should use data for the entire adolescent population. Second, we used the national secondary data consisting of the measures, which were (a) developed for Korean teenagers, and (b) not well-known and widely used internationally. Thus, future studies which verify the cognitive-behavioral model for PMU among adolescents in other countries are needed, using internationally validated measures in psychological well-being, PMU, and negative outcomes. Third, the dependent variables in the study are negative school outcomes and we explored the effects of depressive moods and PMU on negative school outcomes. However, in addition to school, friends and family are important variables in teenagers' daily lives. In the cognitive-behavioral theory, troubles at work, school, and family were dependent variables. Therefore, follow-up studies should identify the effects of depressive moods and PMU on negative consequences of family and friends among adolescents.
Despite these limitations, this study contributes to enhancing our understanding of the cognitive and behavioral process of the way in which depressive moods predict negative school outcomes through PMU over time. Specifically, this pioneering study is noteworthy in applying a cognitive-behavioral model to PMU theoretically: First, while PIU was limited to social skill deficit, PMU added (a) entertainment functions, including mobile games and video watching, and (b) business functions, namely email and Internet lectures. Therefore, the current study extended the scope of cognitive and behavioral disorders. Second, unlike the existing PIU studies, this study focused on maladjustment to school life which was most important for adolescents and provided more useful and practical implications for them. Third, we identified longitudinal associations among the constructs and revealed a new path from depressive moods to negative school outcomes, which was not tested in the cognitive-behavioral model.
Internationally, depressive symptoms and PMU are significant causes of difficulty in adolescents' daily lives including their school lives (Webb et al., 2007), and many younger teenagers have started using mobile phones (Seo & Choi, 2018). Therefore, the findings of the present study can be a source for education and public policies to decrease such negative impacts of PMU from a global perspective. Depressive feelings are prevalent, and their alleviation is the fundamental factor in preventing PMU and adverse school outcomes during adolescence.
Footnotes
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
