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Depression, materialism, and excessive Internet use in relation to compulsive buying
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Comprehensive Psychiatry 52 (2011) 420 – 424 www.elsevier.com/locate/comppsych
Depression, materialism, and excessive Internet use in relation to compulsive buying Astrid Muellera,b,⁎, James E. Mitchellb , Lisa A. Petersonb , Ronald J. Faberc , Kristine J. Steffenb , Ross D. Crosbyb , Laurence Claesd a
Department of Psychosomatic Medicine and Psychotherapy, University Hospital of Erlangen, Erlangen, D-91054, Germany b Neuropsychiatric Research Institute and Department of Clinical Neuroscience, University of North Dakota, School of Medicine and Health Sciences, Fargo, ND 58102, USA c School of Journalism and Mass Communication, University of Minnesota, Minneapolis, MN 55455, USA d Department of Psychology, Katholieke Universiteit Leuven, Leuven, B-3000, Belgium
Abstract Objective: The objective of the study was to examine the relationship between compulsive buying (CB), depression, materialism, and excessive Internet use. Methods: An online survey of 387 consumers was conducted including questions about demographics and shopping venues, the Compulsive Buying Scale, the Patient Health Questionnaire Depression Scale, the Materialistic Values Scale, and questions concerning excessive Internet use. Results: Seventeen percent of the participants reported Compulsive Buying Scale scores less than −1.34 and were considered to be having CB. Participants with CB did not significantly differ from those without CB regarding age, sex, marital status, annual household income, and shopping preferences. Individuals with CB reported more depressive symptoms, higher materialistic values endorsement, and more severe excessive Internet use compared with those without CB. Results of a stepwise logistic regression analysis with CB as the dependent variable showed that materialism and depression were associated with CB, whereas excessive Internet use was not. Conclusions: Materialism and depression jointly influence CB. Further research is needed to examine the influence of materialism on CB in a clinical sample consisting of patients with diagnosed CB. © 2011 Elsevier Inc. All rights reserved.
1. Introduction Compulsive buying (CB) is characterized by shopping and purchasing behavior that results in marked distress and causes interpersonal and financial difficulties [1]. Even though this phenomenon may seem to have emerged relatively recently, it was described and termed oniomania about a hundred years ago [2]. Although there is an ongoing discussion about the appropriate diagnosis, CB can currently be classified in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, as an impulse control disorder not otherwise specified. McElroy and colleagues [3] have proposed diagnostic criteria for this disorder. These include a preoccupation with buying or the experience of irresistible, ⁎ Corresponding author. Department of Psychosomatic Medicine and Psychotherapy, University Hospital of Erlangen, D-91054 Erlangen, Germany. Tel.: +49 09131 8544890; fax: +49 09131 8534145. E-mail address: [email protected] (A. Mueller). 0010-440X/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.comppsych.2010.09.001
intrusive, and/or senseless impulses to buy; frequently purchasing unneeded items or spending beyond one's means; spending more time shopping than intended; and experiencing negative consequences such as distress, impaired social or occupational functioning, and/or financial problems. Faber and O'Guinn [1] developed the Compulsive Buying Scale (CBS), which is based largely on the criteria of McElroy and colleagues [3]. They defined compulsive buyers as those scoring at least 2 standard deviations less than the mean and, using this criterion, estimated the prevalence of CB within the United States to be 8.1%. More recently, Koran and colleagues [4] examined prevalence using the CBS with a larger, more representative general population sample of US adults and reported that 6% of women and 5.5% of men met the criteria for CB, with a sexadjusted prevalence of 5.8%. A variety of characteristics of people with CB have been examined. Previous research has associated CB with high rates of psychiatric comorbidity. In clinical samples, mood and
A. Mueller et al. / Comprehensive Psychiatry 52 (2011) 420–424
anxiety disorders, obsessive-compulsive disorder, compulsive hoarding, personality disorders, and disorders of impulse control, particularly intermittent explosive disorder, occur most frequently in conjunction with CB [3,5-8]. Recently, findings on psychiatric comorbidity in 171 individuals with CB were published that supported the previous research data [9]. Nearly 90% of the treatment-seeking sample reported at least one lifetime Axis I diagnosis. In particular, mood disorders represented the most common comorbid lifetime disorders. With respect to population-based samples, the association between depressive symptoms and CB was supported in a large representative German sample [10]. Several authors have looked at the role of materialism in CB with somewhat conflicting conclusions. Materialistic value is defined as the belief that the acquisition of material goods is a central life goal, prime indicator of success, and a key to happiness and self-definition [11]. Early studies tended to dismiss the impact of materialism, finding either that it was unrelated to CB [12] or that, although there was a relationship, it was due to interpersonal elements of materialism such as envy and nongenerosity, rather than object desire [13]. More recent research has tended to report strong relationships between materialistic values and CB. Rindfleisch et al [14] identified the impact of family structure and materialism on CB. Dittmar [15] showed that materialistic values endorsement presents a strong predictor of individuals' CB. Rose [16] investigated the association between narcissism and CB in undergraduates and reported that materialism and impulse control both mediated this relationship. Findings in consumer research suggest that Internet use possesses characteristics that seem to encourage CB. For example, Lejoyeux et al [17] interviewed 200 women in a Parisian department store and found that those with CB had longer and more frequent connections to online shopping sites. Kukar-Kinney et al [18] investigated the relationship between Internet buying and CB among customers of an Internet clothing retailer. Their findings indicated that people with CB have a stronger motivation to buy on the Internet than at retail stores. They posited that the Internet enables consumers to avoid social interactions and to buy at anytime unobserved. The aim of the present work was to enhance our knowledge about the relationship between CB, depression, materialism, and excessive Internet use. Depression and materialism were hypothesized to be associated with CB. Furthermore, we expected that, besides depression and materialism, excessive Internet use will provide a substantial increase in explained variance of CB tendencies.
2. Procedure To address the aims, an online survey of consumers was conducted. Participation in the study was completely voluntarily. Individuals were recruited through newspaper, Web site postings, and flyers. Any participant who was willing to provide informed consent and was at least 18 years
421
of age was allowed to participate in the study. As an incentive to complete the survey, the respondents received a $10 gas card. Data collection occurred between January 2008 and May 2009. The protocol was approved by the University of North Dakota Institutional Review Board.
3. Measures The online survey had 3 sections. In the first section, demographics questions including age, sex, and annual household income were assessed. Because we expected an influence of shopping venues on CB tendencies, the second section consisted of the following questions: Do you ever browse or shop/Do you make purchase (1) through online shopping, (2) through shopping on Internet auction sites, (3) via TV, (4) via catalogues, (4) in stores, and (5) at garage or rummage sales? In the third section, endorsement to CB, depression, materialistic values, and excessive Internet use was explored. To assess CB, the survey included the CBS [1]. This screening instrument consists of 7 items exploring specific behaviors, motivations, feelings, and financial aspects associated with buying (Cronbach α in the present study was .89). Lower CBS scores indicate a higher level of CB. Faber and O'Guinn [1] developed a scoring system involving a regression equation with item weighting to determine the cutoff score for individuals with CB. A cutoff score less than −1.34 was used to indicate CB. To explore depressive symptoms, we included the Patient Health Questionnaire Depression Scale (PHQ-9; Pfizer) in the survey. The PHQ-9 scores each of the 9 Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria as 0 (not at all) to 3 (nearly every day). The internal consistency of the PHQ-9 in the present study was α = .92. Furthermore, the 11-item version [19] of the Materialistic Values Scale (MVS; Richins [11]) was incorporated in the survey. The MVS measures the notion that possessions and their acquisition are essential for well-being and satisfaction in life (eg, “My life would be better if I owned certain things I don't have”), the extent to which one places possessions and their acquisition at the center of his/her life (eg, “I like a lot of luxury in my life”), and whether or not one judges one's own and others' success by the number and quality of accumulated possessions (eg, “I admire people who own expensive homes, cars, and clothes”). All items (α = .88 in the present study) are rated on a 5-point scale ranging from 1 (strongly agree) to 5 (strongly disagree). Lower levels indicate more materialistic value endorsement. To measure the propensity for excessive Internet use, we included in the survey the following 8 items answered on a 5-point scale ranging from 1 (very often) to 5 (never) that were created for this survey (Internet Use Measurement [IUM]): (1) I feel that my Internet use is out of control. (2) My Internet use has caused problems for me. (3) Others have objected to the amount of time I spend using the Internet. (4) I
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spend more time than I planned to use the Internet. (5) I have attempted to control or cut back on my Internet use. (6) I feel anxious when I am not able to access the Internet. (7) I use the Internet to escape from problems in my life or to relieve unpleasant feelings. (8) I attempt to conceal my Internet use from my family, friends, or other people. The coefficient α value in the present study was .93. Lower scores indicate a higher tendency toward excessive Internet use. 4. Statistical analyses Analyses were performed with SPSS (Chicago, IL) 18.0. The relationships between CB and depression (PHQ-9), materialism (MVS), and excessive Internet use (IUM) were explored using Spearman correlation coefficient. Compulsive buying was defined based on CBS scores less than −1.34. Analysis of variances and χ2 tests were used to compare participants with CB with those without, as appropriate. To examine which variables were associated with CB, we performed a stepwise logistic regression analysis. To correct for multiple comparisons, all tests were based on a significance level of .01.
Table 2 Shopping/buying preferences of those with CB (n = 65) compared with those without CB (n = 322) Non-CB (n = 322) n Online Browsing Purchasing Internet auction sites Browsing Purchasing TV Browsing Purchasing Catalogues Browsing Purchasing Stores Browsing Purchasing Garage and rummage sales Browsing Purchasing
CB (n = 65)
(% among those n without CB)
χ2
(% among those with CB)
276 (85.7) 247 (76.7)
63 (96.9) 59 (90.8)
NS NS
214 (66.5) 146 (45.3)
49 (75.4) 37 (56.9)
NS NS
36 (11.2) 14 (4.3)
17 (26.1) 11 (16.9)
P b .01 NS
212 (65.8) 111 (34.5)
50 (76.9) 26 (40.0)
NS NS
259 (80.4) 254 (78.9)
56 (86.1) 55 (84.6)
NS NS
166 (51.5) 161 (50.0)
43 (66.1) 41 (63.1)
NS NS
5. Results
NS indicates not significant.
5.1. Sample characteristics
(reversed). The CBS scores were positively related to all variables. The correlation between CBS means and age using Spearman ρ did not reveal a significant relationship (r = 0.092, P = .072).
Four hundred forty-three people with a mean (SD) age of 38.8 (14.1) years (range, 18-74 years) responded to the online survey. Cases were dropped listwise when data were missing. This provided a final sample of 387 cases for analysis, with ages ranging from 18 to 74 years (mean ± SD, 39.1 ± 14.0 years). Two thirds of the participants were female. Information from 381 participants on annual household income was available. Forty-eight people (12.6%) reported an annual household income less than $20 000; 71 (18.6%), between $20 001 and $40 000; 81 (21.3%), between $40 001 and $60 000; 68 (17.8%), between $60 001 and $80 000; 60 (15.7%), between $80 001 and $100 000; and 53 (13.9%), more than $100 000. 5.2. Correlations between CB and materialism, depression, excessive Internet use, and age Table 1 displays the correlations between the scores of the CBS (reversed), PHQ-9, MVS (reversed), and IUM
5.3. Comparison of participants with and without CB Seventeen percent (65 of 387) of the participants reported CBS scores less than −1.34 and were considered to be having CB. Participants with CB did not differ significantly from those without CB regarding age (mean ± SD, 38.6 ± 10.7 years vs mean ± SD, 39.2 ± 14.6 years). In addition, the sex difference between the 2 groups was not statistically significant. Among those with CB, 83% were female compared with 74% of the participants in the non-CB group. Furthermore, no significant differences emerged regarding marital status and annual household income between the 2 groups.
Table 3 Depression, materialism, and excessive Internet use of those with CB (n = 65) compared with those without CB (n = 322) Non-CB
Table 1 Correlations between CB, depression, materialism, and excessive Internet use
PHQ-9 MVSa IUMa a
CBSa
PHQ-9
MVSa
0.44⁎ 0.45⁎ 0.38⁎
– 0.34⁎ 0.49⁎
– – 0.38⁎
Scores on the CBS, MVS, and IUM were reversed: higher scores indicate higher levels of CB, materialism, and excessive Internet use. ⁎ P b .01.
PHQ-9 MVSa IUMa
CB
ANOVA
Mean
(SD)
Mean
(SD)
12.79 3.33 33.38
(4.57) (0.64) (6.14)
18.85 2.57 26.52
(7.02) (0.75) (9.18)
F1;385 = 77.73⁎ F1;385 = 70.70⁎ F1;385 = 55.97⁎
ANOVA indicates analysis of variance. a Lower level indicates higher materialistic values/higher propensity to Internet addiction. ⁎ P b .001.
A. Mueller et al. / Comprehensive Psychiatry 52 (2011) 420–424
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Table 4 Summary of logistic regression analyses predicting CB
Step 1 Step 2
a
MVSa PHQ MVSa PHQ-9 IUMa
Regression coefficient β
Standard error
Wald
df
P
Odds ratio
95% Confidence interval
Nagelkerke R2
1.310 0.126 1.167 0.106 0.044
0.263 0.028 0.274 0.029 0.023
24.733 20.636 18.156 13.442 3.602
1 1 1 1 1
.000 .000 .000 .000 .058
0.270 1.134 0.311 1.112 0.957
0.161-0.452 1.074-1.197 0.182-0.532 1.051-1.177 0.915-1.001
0.338 0.350
Scores on the MVS/IUM were reversed: higher scores indicate higher levels of materialism/excessive Internet use.
Participants with CB reported a tendency to browse and purchase more often in different settings. As can be seen in Table 2, TV browsing was the only variable where the difference between the 2 groups reached statistical significance. With respect to self-ratings, individuals with CB reported more depressive symptoms, higher materialistic values endorsement, and more severe excessive Internet use compared with those without CB (Table 3). To explore which factors were associated with CB in our sample, we conducted a stepwise logistic regression analysis with CB as the dependent variable. Because age, sex, marital status, annual household income, and buying preferences (purchasing online, through Internet auction sites, catalogues, stores, and rummage sales) did not differ between participants with CB and participants without CB, these variables were not included in the regression. The following variables were entered in stepwise order: in the first step, the total scores of the PHQ Depression Scale and the total scores of the MVS, and in the second step, the total scores of the IUM. Table 4 summarizes the results. Only depression and materialism were significantly related to CB, with materialism being the strongest predictor. The Nagelkerke R2 change in step 2 after IUM scores had been entered was only 0.012. None of the 2-way interactions were significant.
6. Discussion The present study attempted to investigate the relationship between CB and depression, materialism, and excessive Internet use. The prevalence of CB observed in the present study, as assessed with the CBS, is relatively high at 17%. By comparison, representative studies that also used the CBS have reported estimated prevalence rates of about 6% to 8% in the population [4,10]. However, it seems that our finding resembles prevalence rates of other consumer surveys. Dittmar [19] found prevalence rates of 13% among participants who responded to a mail survey using the CBS. Furthermore, Kukar-Kinney and colleagues [18] conducted a survey on customers of an Internet clothing retailer using a different 6-item CBS developed by Ridgway et al [20]. They found that 17.7% of the 314 respondents were affected by CB. It may be that, for online surveys, more people who shop or buy excessively feel encouraged to participate. As hypothesized, materialistic value endorsement and depressive symptoms were significantly associated with CB
tendencies. Our results confirm the more recent reports of a strong link between materialism and tendencies toward CB [15,16,19,21]. The findings are also in line with previous research indicating a prevalent co-occurrence of CB and depression in both clinical and population-based samples [3,9,10]. Interestingly, however, the interaction of these 2 variables was not significant, suggesting that they are independent contributors to CB rather than having a synergistic effect. The findings may suggest that there are 2 separate paths to CB. This is consistent with the work by DeSarbo and Edwards [22] that identified 2 distinct clusters of compulsive buyers. One group was made up of people who were driven mainly by materialism and a desire for objects. They also tended to be more impulsive and have poor coping skills. The second group was composed of people whose buying was more motivated by internal feelings such as low self-esteem and having a short-term sense of power or control. This second group might be more likely to have depression. In contrast to the other findings, excessive Internet use was not significantly associated with CB. Accordingly, the addition of excessive Internet use into the regression did not lead to a notable increase in explained variance of CB. Given the fact that participants with CB had reported a significant higher tendency toward excessive Internet use than those without CB (Table 3), their propensity toward elevated Internet use may include other forms of Internet addiction beyond shopping, such as excessive gaming [23,24]. In accordance with this suggestion, in our sample, individuals with CB did not report significantly higher preferences for online shopping or browsing/purchasing through Internet auction sites compared with those without CB. This is in line with our clinical experience. Many patients with CB enjoy the interaction with others while shopping (eg, salesperson) and prefer shopping in stores. With regard to the impact of shopping venues on CB, we could not find an apparent relationship. Although individuals with CB reported a tendency to browse and purchase more often in different venues, only for browsing through TV (not for purchasing through TV) did the difference between the 2 groups reached statistical significance. Furthermore, sex did not significantly relate to CB. Another finding that is worth noting is that, in the present sample, participants with CB were not significantly younger than those without CB. This is in contrast to prevailing results referring to a negative association between age and CB [4,10,25]. The findings warrant some concern regarding
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the representativeness of our online survey sample. Thus, the study is limited by the Internet-based sample including uncertainty over response rate and issues involving sampling bias and nonrepresentativeness. However, online surveys provide convenience and allow for research involving individuals in distant locations. Another limitation is the exclusive use of self-report instruments. In addition, although we tested the association between materialism, depression, and CB, causality cannot be established using a cross-sectional design. Future research might focus on the timing of these relationships or possible mediation effects using prospective designs. Despite these limitations, the results may have implications for treatment. Therapeutic interventions that do not address patients' endorsement to materialism may be less likely to provide long-term improvement of some patients with CB. Thus, psychotherapy needs to determine the causes of CB and address the appropriate cause, be it depression and maladaptive thoughts and feelings associated with CB or patients' underlying materialistic values, to achieve sustained improvement of CB. Further research is needed to examine the influence of materialism on CB in a clinical sample consisting of patients with diagnosed CB and to determine if materialism represents a separate route to CB. References [1] Faber RJ, O'Guinn TC. A clinical screener for compulsive buying. J Consum Res 1992;19:459-69. [2] Kraepelin E. Psychiatrie. Ein Lehrbuch für Studierende und Ärzte. Leipzig: Johann Ambrosius Barth; 1909. [3] McElroy SL, Keck PE, Pope HG, Smith JMR, Strakowski SM. Compulsive buying: a report of 20 cases. J Clin Psychiatry 1994;55: 242-8. [4] Koran LM, Faber RJ, Aboujoude E, Large MD, Serpe RT. Estimated prevalence of compulsive buying behavior in the United States. Am J Psychiatry 2006;163:1806-12. [5] Schlosser S, Black DW, Repertinger S, Freet D. Compulsive buying. Demography, phenomenology and comorbidity in 46 subjects. Gen Hosp Psychiatry 1994;16:205-12. [6] Black DW, Gabel J, Hansen J, Schlosser S. A double-blind comparison of fluvoxamine versus placebo in the treatment of compulsive buying disorder. Ann Clin Psychiatry 2000;12:205-11. [7] Mitchell JE, Redlin J, Wonderlich S, Crosby R, Faber R, Miltenberger R, et al. The relationship between compulsive buying and eating disorders. Int J Eat Disord 2002;32:107-11.
[8] Frost RO, Tolin DF, Steketee G, Fitch KE, Selbo-Bruns A. Excessive acquisition in hoarding. J Anxiety Disord 2009;23:632-9. [9] Mueller A, Mitchell JE, Black DW, Crosby RD, Berg K, de Zwaan M. Latent profile analysis and comorbidity in a sample of individuals with compulsive buying disorder. Psychiatry Res 2010; 178:348-53. [10] Mueller A, Mitchell JE, Crosby RD, Gefeller O, Faber RJ, Martin A, et al. Estimated prevalence of compulsive buying in Germany and its association with sociodemographic characteristics and depressive symptoms. Psychiatry Res 2010 [Epub ahead of print]. [11] Richins M. The Materialistic Values Scale: a re-inquiry into its measurement properties and the development of a short form. J Consum Res 2004;31:209-19. [12] Scherhorn G, Reisch LA, Raab G. Addictive buying in West Germany: an empirical study. J Consum Policy 1990;13:355-87. [13] O'Guinn TC, Faber RJ. Compulsive buying: a phenomenological exploration. J Consum Res 1989;16:147-57. [14] Rindfleisch A, Burrouhs JE, Denton F. Family structure, materialism, and compulsive consumption. J Consum Res 1997;23:312-25. [15] Dittmar H. A new look at compulsive buying: self-discrepancies and materialistic values as predictors of compulsive buying tendency. J Soc Clin Psychol 2005;24:806-33. [16] Rose P. Mediators of the association between narcissism and compulsive buying: the roles of materialism and impulse control. Psychol Addict Behav 2007;21:576-81. [17] Lejoyeux M, Mathieu K, Embouazza H, Huet F, Lequen V. Prevalence of compulsive buying among customers of a Parisian general store. Compr Psychiatry 2007;48:42-6. [18] Kukar-Kinney M, Ridgway NM, Monroe KB. The relationship between consumers' tendencies to buy compulsively and their motivations to shop and buy on the Internet. J Retail 2009;85: 298-307. [19] Dittmar H. Compulsive buying—a growing concern? An examination of gender, age, and endorsement of materialistic values as predictors. Br J Psychol 2005;96:467-91. [20] Ridgway NM, Kukar-Kinney M, Monroe KB. An expanded conceptualization and a new measure of compulsive buying. J Consum Res 2008;35:622-39. [21] Roberts JA, Manolis C, Tanner JF. Interpersonal influence and adolescent materialism and compulsive buying. Soc Influence 2008;3: 114-31. [22] DeSarbo W, Edwards E. Typologies of compulsive buying behavior: a constrained clusterwise regression approach. J Consum Psychol 1996; 5:231-62. [23] van Rooij AJ, Schoenmakers TM, van de Eijnden RJ, van de Mheen D. Compulsive Internet use: the role of online gaming and other Internet applications. J Adolesc Health 2010;47:51-7. [24] Weinstein A, Lejoyeux M. Internet addiction or excessive Internet use. Am J Drug Alcohol Abuse 2010;36:277-83. [25] Neuner M, Raab G, Reisch L. Compulsive buying in maturing consumer societies: an empirical re-inquiry. J Econ Psychol 2005;26: 509-22.
Comprehensive Psychiatry 52 (2011) 420 – 424 www.elsevier.com/locate/comppsych
Depression, materialism, and excessive Internet use in relation to compulsive buying Astrid Muellera,b,⁎, James E. Mitchellb , Lisa A. Petersonb , Ronald J. Faberc , Kristine J. Steffenb , Ross D. Crosbyb , Laurence Claesd a
Department of Psychosomatic Medicine and Psychotherapy, University Hospital of Erlangen, Erlangen, D-91054, Germany b Neuropsychiatric Research Institute and Department of Clinical Neuroscience, University of North Dakota, School of Medicine and Health Sciences, Fargo, ND 58102, USA c School of Journalism and Mass Communication, University of Minnesota, Minneapolis, MN 55455, USA d Department of Psychology, Katholieke Universiteit Leuven, Leuven, B-3000, Belgium
Abstract Objective: The objective of the study was to examine the relationship between compulsive buying (CB), depression, materialism, and excessive Internet use. Methods: An online survey of 387 consumers was conducted including questions about demographics and shopping venues, the Compulsive Buying Scale, the Patient Health Questionnaire Depression Scale, the Materialistic Values Scale, and questions concerning excessive Internet use. Results: Seventeen percent of the participants reported Compulsive Buying Scale scores less than −1.34 and were considered to be having CB. Participants with CB did not significantly differ from those without CB regarding age, sex, marital status, annual household income, and shopping preferences. Individuals with CB reported more depressive symptoms, higher materialistic values endorsement, and more severe excessive Internet use compared with those without CB. Results of a stepwise logistic regression analysis with CB as the dependent variable showed that materialism and depression were associated with CB, whereas excessive Internet use was not. Conclusions: Materialism and depression jointly influence CB. Further research is needed to examine the influence of materialism on CB in a clinical sample consisting of patients with diagnosed CB. © 2011 Elsevier Inc. All rights reserved.
1. Introduction Compulsive buying (CB) is characterized by shopping and purchasing behavior that results in marked distress and causes interpersonal and financial difficulties [1]. Even though this phenomenon may seem to have emerged relatively recently, it was described and termed oniomania about a hundred years ago [2]. Although there is an ongoing discussion about the appropriate diagnosis, CB can currently be classified in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, as an impulse control disorder not otherwise specified. McElroy and colleagues [3] have proposed diagnostic criteria for this disorder. These include a preoccupation with buying or the experience of irresistible, ⁎ Corresponding author. Department of Psychosomatic Medicine and Psychotherapy, University Hospital of Erlangen, D-91054 Erlangen, Germany. Tel.: +49 09131 8544890; fax: +49 09131 8534145. E-mail address: [email protected] (A. Mueller). 0010-440X/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.comppsych.2010.09.001
intrusive, and/or senseless impulses to buy; frequently purchasing unneeded items or spending beyond one's means; spending more time shopping than intended; and experiencing negative consequences such as distress, impaired social or occupational functioning, and/or financial problems. Faber and O'Guinn [1] developed the Compulsive Buying Scale (CBS), which is based largely on the criteria of McElroy and colleagues [3]. They defined compulsive buyers as those scoring at least 2 standard deviations less than the mean and, using this criterion, estimated the prevalence of CB within the United States to be 8.1%. More recently, Koran and colleagues [4] examined prevalence using the CBS with a larger, more representative general population sample of US adults and reported that 6% of women and 5.5% of men met the criteria for CB, with a sexadjusted prevalence of 5.8%. A variety of characteristics of people with CB have been examined. Previous research has associated CB with high rates of psychiatric comorbidity. In clinical samples, mood and
A. Mueller et al. / Comprehensive Psychiatry 52 (2011) 420–424
anxiety disorders, obsessive-compulsive disorder, compulsive hoarding, personality disorders, and disorders of impulse control, particularly intermittent explosive disorder, occur most frequently in conjunction with CB [3,5-8]. Recently, findings on psychiatric comorbidity in 171 individuals with CB were published that supported the previous research data [9]. Nearly 90% of the treatment-seeking sample reported at least one lifetime Axis I diagnosis. In particular, mood disorders represented the most common comorbid lifetime disorders. With respect to population-based samples, the association between depressive symptoms and CB was supported in a large representative German sample [10]. Several authors have looked at the role of materialism in CB with somewhat conflicting conclusions. Materialistic value is defined as the belief that the acquisition of material goods is a central life goal, prime indicator of success, and a key to happiness and self-definition [11]. Early studies tended to dismiss the impact of materialism, finding either that it was unrelated to CB [12] or that, although there was a relationship, it was due to interpersonal elements of materialism such as envy and nongenerosity, rather than object desire [13]. More recent research has tended to report strong relationships between materialistic values and CB. Rindfleisch et al [14] identified the impact of family structure and materialism on CB. Dittmar [15] showed that materialistic values endorsement presents a strong predictor of individuals' CB. Rose [16] investigated the association between narcissism and CB in undergraduates and reported that materialism and impulse control both mediated this relationship. Findings in consumer research suggest that Internet use possesses characteristics that seem to encourage CB. For example, Lejoyeux et al [17] interviewed 200 women in a Parisian department store and found that those with CB had longer and more frequent connections to online shopping sites. Kukar-Kinney et al [18] investigated the relationship between Internet buying and CB among customers of an Internet clothing retailer. Their findings indicated that people with CB have a stronger motivation to buy on the Internet than at retail stores. They posited that the Internet enables consumers to avoid social interactions and to buy at anytime unobserved. The aim of the present work was to enhance our knowledge about the relationship between CB, depression, materialism, and excessive Internet use. Depression and materialism were hypothesized to be associated with CB. Furthermore, we expected that, besides depression and materialism, excessive Internet use will provide a substantial increase in explained variance of CB tendencies.
2. Procedure To address the aims, an online survey of consumers was conducted. Participation in the study was completely voluntarily. Individuals were recruited through newspaper, Web site postings, and flyers. Any participant who was willing to provide informed consent and was at least 18 years
421
of age was allowed to participate in the study. As an incentive to complete the survey, the respondents received a $10 gas card. Data collection occurred between January 2008 and May 2009. The protocol was approved by the University of North Dakota Institutional Review Board.
3. Measures The online survey had 3 sections. In the first section, demographics questions including age, sex, and annual household income were assessed. Because we expected an influence of shopping venues on CB tendencies, the second section consisted of the following questions: Do you ever browse or shop/Do you make purchase (1) through online shopping, (2) through shopping on Internet auction sites, (3) via TV, (4) via catalogues, (4) in stores, and (5) at garage or rummage sales? In the third section, endorsement to CB, depression, materialistic values, and excessive Internet use was explored. To assess CB, the survey included the CBS [1]. This screening instrument consists of 7 items exploring specific behaviors, motivations, feelings, and financial aspects associated with buying (Cronbach α in the present study was .89). Lower CBS scores indicate a higher level of CB. Faber and O'Guinn [1] developed a scoring system involving a regression equation with item weighting to determine the cutoff score for individuals with CB. A cutoff score less than −1.34 was used to indicate CB. To explore depressive symptoms, we included the Patient Health Questionnaire Depression Scale (PHQ-9; Pfizer) in the survey. The PHQ-9 scores each of the 9 Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria as 0 (not at all) to 3 (nearly every day). The internal consistency of the PHQ-9 in the present study was α = .92. Furthermore, the 11-item version [19] of the Materialistic Values Scale (MVS; Richins [11]) was incorporated in the survey. The MVS measures the notion that possessions and their acquisition are essential for well-being and satisfaction in life (eg, “My life would be better if I owned certain things I don't have”), the extent to which one places possessions and their acquisition at the center of his/her life (eg, “I like a lot of luxury in my life”), and whether or not one judges one's own and others' success by the number and quality of accumulated possessions (eg, “I admire people who own expensive homes, cars, and clothes”). All items (α = .88 in the present study) are rated on a 5-point scale ranging from 1 (strongly agree) to 5 (strongly disagree). Lower levels indicate more materialistic value endorsement. To measure the propensity for excessive Internet use, we included in the survey the following 8 items answered on a 5-point scale ranging from 1 (very often) to 5 (never) that were created for this survey (Internet Use Measurement [IUM]): (1) I feel that my Internet use is out of control. (2) My Internet use has caused problems for me. (3) Others have objected to the amount of time I spend using the Internet. (4) I
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spend more time than I planned to use the Internet. (5) I have attempted to control or cut back on my Internet use. (6) I feel anxious when I am not able to access the Internet. (7) I use the Internet to escape from problems in my life or to relieve unpleasant feelings. (8) I attempt to conceal my Internet use from my family, friends, or other people. The coefficient α value in the present study was .93. Lower scores indicate a higher tendency toward excessive Internet use. 4. Statistical analyses Analyses were performed with SPSS (Chicago, IL) 18.0. The relationships between CB and depression (PHQ-9), materialism (MVS), and excessive Internet use (IUM) were explored using Spearman correlation coefficient. Compulsive buying was defined based on CBS scores less than −1.34. Analysis of variances and χ2 tests were used to compare participants with CB with those without, as appropriate. To examine which variables were associated with CB, we performed a stepwise logistic regression analysis. To correct for multiple comparisons, all tests were based on a significance level of .01.
Table 2 Shopping/buying preferences of those with CB (n = 65) compared with those without CB (n = 322) Non-CB (n = 322) n Online Browsing Purchasing Internet auction sites Browsing Purchasing TV Browsing Purchasing Catalogues Browsing Purchasing Stores Browsing Purchasing Garage and rummage sales Browsing Purchasing
CB (n = 65)
(% among those n without CB)
χ2
(% among those with CB)
276 (85.7) 247 (76.7)
63 (96.9) 59 (90.8)
NS NS
214 (66.5) 146 (45.3)
49 (75.4) 37 (56.9)
NS NS
36 (11.2) 14 (4.3)
17 (26.1) 11 (16.9)
P b .01 NS
212 (65.8) 111 (34.5)
50 (76.9) 26 (40.0)
NS NS
259 (80.4) 254 (78.9)
56 (86.1) 55 (84.6)
NS NS
166 (51.5) 161 (50.0)
43 (66.1) 41 (63.1)
NS NS
5. Results
NS indicates not significant.
5.1. Sample characteristics
(reversed). The CBS scores were positively related to all variables. The correlation between CBS means and age using Spearman ρ did not reveal a significant relationship (r = 0.092, P = .072).
Four hundred forty-three people with a mean (SD) age of 38.8 (14.1) years (range, 18-74 years) responded to the online survey. Cases were dropped listwise when data were missing. This provided a final sample of 387 cases for analysis, with ages ranging from 18 to 74 years (mean ± SD, 39.1 ± 14.0 years). Two thirds of the participants were female. Information from 381 participants on annual household income was available. Forty-eight people (12.6%) reported an annual household income less than $20 000; 71 (18.6%), between $20 001 and $40 000; 81 (21.3%), between $40 001 and $60 000; 68 (17.8%), between $60 001 and $80 000; 60 (15.7%), between $80 001 and $100 000; and 53 (13.9%), more than $100 000. 5.2. Correlations between CB and materialism, depression, excessive Internet use, and age Table 1 displays the correlations between the scores of the CBS (reversed), PHQ-9, MVS (reversed), and IUM
5.3. Comparison of participants with and without CB Seventeen percent (65 of 387) of the participants reported CBS scores less than −1.34 and were considered to be having CB. Participants with CB did not differ significantly from those without CB regarding age (mean ± SD, 38.6 ± 10.7 years vs mean ± SD, 39.2 ± 14.6 years). In addition, the sex difference between the 2 groups was not statistically significant. Among those with CB, 83% were female compared with 74% of the participants in the non-CB group. Furthermore, no significant differences emerged regarding marital status and annual household income between the 2 groups.
Table 3 Depression, materialism, and excessive Internet use of those with CB (n = 65) compared with those without CB (n = 322) Non-CB
Table 1 Correlations between CB, depression, materialism, and excessive Internet use
PHQ-9 MVSa IUMa a
CBSa
PHQ-9
MVSa
0.44⁎ 0.45⁎ 0.38⁎
– 0.34⁎ 0.49⁎
– – 0.38⁎
Scores on the CBS, MVS, and IUM were reversed: higher scores indicate higher levels of CB, materialism, and excessive Internet use. ⁎ P b .01.
PHQ-9 MVSa IUMa
CB
ANOVA
Mean
(SD)
Mean
(SD)
12.79 3.33 33.38
(4.57) (0.64) (6.14)
18.85 2.57 26.52
(7.02) (0.75) (9.18)
F1;385 = 77.73⁎ F1;385 = 70.70⁎ F1;385 = 55.97⁎
ANOVA indicates analysis of variance. a Lower level indicates higher materialistic values/higher propensity to Internet addiction. ⁎ P b .001.
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Table 4 Summary of logistic regression analyses predicting CB
Step 1 Step 2
a
MVSa PHQ MVSa PHQ-9 IUMa
Regression coefficient β
Standard error
Wald
df
P
Odds ratio
95% Confidence interval
Nagelkerke R2
1.310 0.126 1.167 0.106 0.044
0.263 0.028 0.274 0.029 0.023
24.733 20.636 18.156 13.442 3.602
1 1 1 1 1
.000 .000 .000 .000 .058
0.270 1.134 0.311 1.112 0.957
0.161-0.452 1.074-1.197 0.182-0.532 1.051-1.177 0.915-1.001
0.338 0.350
Scores on the MVS/IUM were reversed: higher scores indicate higher levels of materialism/excessive Internet use.
Participants with CB reported a tendency to browse and purchase more often in different settings. As can be seen in Table 2, TV browsing was the only variable where the difference between the 2 groups reached statistical significance. With respect to self-ratings, individuals with CB reported more depressive symptoms, higher materialistic values endorsement, and more severe excessive Internet use compared with those without CB (Table 3). To explore which factors were associated with CB in our sample, we conducted a stepwise logistic regression analysis with CB as the dependent variable. Because age, sex, marital status, annual household income, and buying preferences (purchasing online, through Internet auction sites, catalogues, stores, and rummage sales) did not differ between participants with CB and participants without CB, these variables were not included in the regression. The following variables were entered in stepwise order: in the first step, the total scores of the PHQ Depression Scale and the total scores of the MVS, and in the second step, the total scores of the IUM. Table 4 summarizes the results. Only depression and materialism were significantly related to CB, with materialism being the strongest predictor. The Nagelkerke R2 change in step 2 after IUM scores had been entered was only 0.012. None of the 2-way interactions were significant.
6. Discussion The present study attempted to investigate the relationship between CB and depression, materialism, and excessive Internet use. The prevalence of CB observed in the present study, as assessed with the CBS, is relatively high at 17%. By comparison, representative studies that also used the CBS have reported estimated prevalence rates of about 6% to 8% in the population [4,10]. However, it seems that our finding resembles prevalence rates of other consumer surveys. Dittmar [19] found prevalence rates of 13% among participants who responded to a mail survey using the CBS. Furthermore, Kukar-Kinney and colleagues [18] conducted a survey on customers of an Internet clothing retailer using a different 6-item CBS developed by Ridgway et al [20]. They found that 17.7% of the 314 respondents were affected by CB. It may be that, for online surveys, more people who shop or buy excessively feel encouraged to participate. As hypothesized, materialistic value endorsement and depressive symptoms were significantly associated with CB
tendencies. Our results confirm the more recent reports of a strong link between materialism and tendencies toward CB [15,16,19,21]. The findings are also in line with previous research indicating a prevalent co-occurrence of CB and depression in both clinical and population-based samples [3,9,10]. Interestingly, however, the interaction of these 2 variables was not significant, suggesting that they are independent contributors to CB rather than having a synergistic effect. The findings may suggest that there are 2 separate paths to CB. This is consistent with the work by DeSarbo and Edwards [22] that identified 2 distinct clusters of compulsive buyers. One group was made up of people who were driven mainly by materialism and a desire for objects. They also tended to be more impulsive and have poor coping skills. The second group was composed of people whose buying was more motivated by internal feelings such as low self-esteem and having a short-term sense of power or control. This second group might be more likely to have depression. In contrast to the other findings, excessive Internet use was not significantly associated with CB. Accordingly, the addition of excessive Internet use into the regression did not lead to a notable increase in explained variance of CB. Given the fact that participants with CB had reported a significant higher tendency toward excessive Internet use than those without CB (Table 3), their propensity toward elevated Internet use may include other forms of Internet addiction beyond shopping, such as excessive gaming [23,24]. In accordance with this suggestion, in our sample, individuals with CB did not report significantly higher preferences for online shopping or browsing/purchasing through Internet auction sites compared with those without CB. This is in line with our clinical experience. Many patients with CB enjoy the interaction with others while shopping (eg, salesperson) and prefer shopping in stores. With regard to the impact of shopping venues on CB, we could not find an apparent relationship. Although individuals with CB reported a tendency to browse and purchase more often in different venues, only for browsing through TV (not for purchasing through TV) did the difference between the 2 groups reached statistical significance. Furthermore, sex did not significantly relate to CB. Another finding that is worth noting is that, in the present sample, participants with CB were not significantly younger than those without CB. This is in contrast to prevailing results referring to a negative association between age and CB [4,10,25]. The findings warrant some concern regarding
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the representativeness of our online survey sample. Thus, the study is limited by the Internet-based sample including uncertainty over response rate and issues involving sampling bias and nonrepresentativeness. However, online surveys provide convenience and allow for research involving individuals in distant locations. Another limitation is the exclusive use of self-report instruments. In addition, although we tested the association between materialism, depression, and CB, causality cannot be established using a cross-sectional design. Future research might focus on the timing of these relationships or possible mediation effects using prospective designs. Despite these limitations, the results may have implications for treatment. Therapeutic interventions that do not address patients' endorsement to materialism may be less likely to provide long-term improvement of some patients with CB. Thus, psychotherapy needs to determine the causes of CB and address the appropriate cause, be it depression and maladaptive thoughts and feelings associated with CB or patients' underlying materialistic values, to achieve sustained improvement of CB. Further research is needed to examine the influence of materialism on CB in a clinical sample consisting of patients with diagnosed CB and to determine if materialism represents a separate route to CB. References [1] Faber RJ, O'Guinn TC. A clinical screener for compulsive buying. J Consum Res 1992;19:459-69. [2] Kraepelin E. Psychiatrie. Ein Lehrbuch für Studierende und Ärzte. Leipzig: Johann Ambrosius Barth; 1909. [3] McElroy SL, Keck PE, Pope HG, Smith JMR, Strakowski SM. Compulsive buying: a report of 20 cases. J Clin Psychiatry 1994;55: 242-8. [4] Koran LM, Faber RJ, Aboujoude E, Large MD, Serpe RT. Estimated prevalence of compulsive buying behavior in the United States. Am J Psychiatry 2006;163:1806-12. [5] Schlosser S, Black DW, Repertinger S, Freet D. Compulsive buying. Demography, phenomenology and comorbidity in 46 subjects. Gen Hosp Psychiatry 1994;16:205-12. [6] Black DW, Gabel J, Hansen J, Schlosser S. A double-blind comparison of fluvoxamine versus placebo in the treatment of compulsive buying disorder. Ann Clin Psychiatry 2000;12:205-11. [7] Mitchell JE, Redlin J, Wonderlich S, Crosby R, Faber R, Miltenberger R, et al. The relationship between compulsive buying and eating disorders. Int J Eat Disord 2002;32:107-11.
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