A randomised controlled trial of a self-guided internet intervention promoting well-being Joanna Mitchell a, * , Rosanna Stanimirovic b , Britt Klein c , Dianne Vella-Brodrick a a School of Psychology, Psychiatry and Psychological Medicine, Monash University, P.O. Box 197, Caulfield East, Vic. 3145, Australia b Department of Performance Psychology, Australian Institute of Sport, Bruce, ACT, Australia c National eTherapy Centre for Anxiety Disorders, Faculty of Life and Social Sciences, Swinburne University, Hawthorn, Vic., Australia article info Article history: Available online 16 March 2009 Keywords: Subjective well-being Internet Positive psychology Strengths Cognitive-behavioural therapy Happiness Health promotion abstract Positive psychology is paving the way for interventions that enduringly enhance well-being and the internet offers the potential to disseminate these interventions to a broad audience in an accessible and sustainable manner. There is now sufficient evidence demonstrating the efficacy of internet interven- tions for mental illness treatment and prevention, but little is known about enhancing well-being. The current study examined the efficacy of a positive psychology internet-based intervention by adopting a randomised controlled trial design to compare a strengths intervention, a problem solving intervention and a placebo control. Participants (n = 160) completed measures of well-being (PWI-A, SWLS, PANAS, OTH) and mental illness (DASS-21) at pre-assessment, post-assessment and 3-month follow-up. Well- being increased for the strengths group at post- and follow-up assessment on the PWI-A, but not the SWLS or PANAS. Significant changes were detected on the OTH subscales of engagement and pleasure. No changes in mental illness were detected by group or time. Attrition from the study was 83% at 3- month follow-up, with significant group differences in adherence to the intervention: strengths (34%), problem solving (15.5%) and placebo control (42.6%). Although the results are mixed, it appears possible to enhance the cognitive component of well-being via a self-guided internet intervention. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Enhancing well-being at a population level is explored in this introduction in the context of two relatively young disciplines, namely positive psychology and internet interventions. An over- view of theory and research in positive psychology and then inter- net interventions is presented as a rationale for the current study. 1.1. Positive psychology, mental health and well-being The positive psychology movement has helped create the re- search momentum necessary to broaden mental health knowledge and understanding beyond a focus on illness and its direct allevia- tion. Positive psychology is the scientific study of well-being and optimal functioning, focusing on positive emotions, character traits and enabling institutions (Seligman & Csikszentmihalyi, 2000). The proponents of this movement aim to bring together and develop previously disparate lines of theory and research to provide a com- plete picture of mental health (Duckworth, Steen, & Seligman, 2005; Seligman, Steen, Park, & Peterson, 2005). The notion of a complete picture of health is reflected in the World Health Organ- isations definition of mental health as: ...a state of well-being in which the individual realizes his or her own abilities, can cope with the normal stresses of life, can work productively and fruitfully, and is able to make a con- tribution to his or her own community. (WHO, 2001a, p. 1). This definition encapsulates the idea that mental health is the presence of well-being and not just the absence of mental illness. To test a model of complete mental health and psychosocial func- tioning Keyes (2005) surveyed a nationally representative sample of 3032 American adults. The results supported the theory that mental health and mental illness are independent but correlated axes; and not merely opposite ends of a continuum. Moreover, Keyes found that participants with no mental illness but low well-being (Keyes labels this languishing) had equivalently poor psychosocial outcomes as the participants with a mental illness. Consequently, promoting well-being and optimal psychosocial functioning is important in its own right, and not just an adjunct to mental illness treatment and prevention. Well-being, also referred to by some researchers as happiness (these terms will be used interchangeably), is a complex construct concerned with optimal experience and functioning (Ryan & Deci, 2001). There are two major conceptual approaches to defining and 0747-5632/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.chb.2009.02.003 * Corresponding author. Tel.: +61 3 9214 5867; fax: +61 3 9214 5260. E-mail address: psychjm@gmail.com (J. Mitchell). Computers in Human Behavior 25 (2009) 749–760 Contents lists available at ScienceDirect Computers in Human Behavior journal homepage: www.elsevier.com/locate/comphumbeh