Web-based mood induction

Abstract

This article introduces the methodology of Web-based mood induction and it presents empirical evidence for its feasibility. The Velten procedure, autobiographical recall, and mood-suggestive photographs were tested for their effectiveness in evoking either a positive or a negative mood when compared to an untreated control group. The Velten technique and the photographs successfully deteriorated mood, but were unsuccessful in generating a positive mood. Autobiographical recall failed to induce either positive or negative mood. The effectiveness of these on-line techniques is compared with the effectiveness of similar off-line mood induction procedures.

This article is based on the first author's doctoral dissertation at the University of Erlangen-Nürnberg, Nürnberg, Bavaria, Germany, 2002.

This article is based on the first author's doctoral dissertation at the University of Erlangen-Nürnberg, Nürnberg, Bavaria, Germany, 2002.

Acknowledgments

This work has been supported by a University of Erlangen-Nürnberg doctoral scholarship (HWP) to the first author, by the Social Science Research Center (SFZ) of the University of Erlangen-Nürnberg, and by grant No. 722/3-2 from the Deutsche Forschungsgemeinschaft.

Notes

This article is based on the first author's doctoral dissertation at the University of Erlangen-Nürnberg, Nürnberg, Bavaria, Germany, 2002.

¹The two effects are estimated on the basis of Stritzke et al.'s (1995) fig. 1, lower panel.

²The effect's unbiased size, however, could not be determined because the relevant information was not provided. Moreover, the slides’ presentation was accompanied by playing back the victims name, occupation, and cause of injury from a tape. The effect of this additional information on the participants’ mood cannot be determined.

³We did not adjust significance levels to correct for multiple testing. These MIPs are prototypes that are intended to be used and tested in further experiments, so a possible Type 1 error can be rectified in future research. In addition, when exploring new research avenues as is the case here, reducing the risk of overlooking a true effect (which could result in the premature abandonment of an MIP) is worth taking the risk of falsely assuming that an MIP is suitable.

⁴These and the following mean effect sizes are based on our reanalysis of Westermann et al.'s (1996) data. To obtain mean effects, each individual effect size was Fisher-transformed and weighted by sample size (Hedges & Olkin, 1985, pp. 230–231). Although this introduces minor statistical bias (Glass et al., 1981), all effects were included in this reanalysis.

⁵Larsen and Sinnett (1991) did not differentiate between negative and positive mood induction.

⁶Westermann et al. (1996) used Rosenthal's (1991) formula to calculate repeated-measures effect sizes (R. Westermann, personal communication, 15 August, 2001). Dunlap et al. (1996) demonstrated that this calculation rule can lead to massive overestimations.

⁷Meta-analytical effectiveness scores are likely to suffer from publication bias. Meta-analyses usually comprise both methodological articles examining MIPs’ effectiveness and papers investigating the influence of mood on other dependent variables. For methodological articles, publication bias is probably negligible. However, it can be enormous for other studies, because many journals do not publish papers on the impact of mood on other variables if the mood induction did not work. Indeed, Westermann et al. (1996) identified study purpose to be a moderator of effect size. In a reanalysis of Westermann et al.'s (1996) data we found a difference in mean effect size between methodological papers (r=.37) and other articles (r=.48), which gives a clue as to how much smaller true effects are.