Date Published: June 4, 2019
Publisher: Public Library of Science
Author(s): David Marcusson-Clavertz, Oscar N. E. Kjell, Stefan D. Persson, Etzel Cardeña, Thomas M. Olino.
Film clips, music, and self-referential statements (termed Velten, after their originator) have been successfully used to temporarily induce sadness and happiness. However, there is little research on the effectiveness of these procedures combined, particularly in internet-based settings, and whether Velten statements contribute to alter mood beyond the effect of simple instructions to close one’s eyes and enter the targeted mood. In Study 1 (N = 106) we examined the effectiveness 80 Velten statements (positive, negative, neutral-self, neutral-facts) to create brief and effective sets that might be used in future research. In Study 2 (N = 445) we examined the effect size of 8-min combined mood induction procedures, which presented video clips in the first half and music excerpts with Velten statements or closed eyes instructions in the second half. Participants answered questionnaires on social desirability, joviality, and sadness before being randomly assigned to 1 of 7 groups varying in Valence (positive, negative, neutral) and Velten (closed eyes control, self-referential Velten, and, in the case of neutral condition, factual statements). Subsequently, participants completed the joviality and sadness scales a second time. Compared to the neutral conditions, the positive mood inductions increased joviality (Hedges G = 1.35, 95% CI [1.07, 1.63]), whereas the negative mood inductions increased sadness (Hedges G = 1.28, 95% CI [1.01, 1.55]). We did not observe any significant difference between Velten and closed eyes instructions in inducing joviality or sadness, nor did we observe any significant difference between neutral Velten statements referring to self and facts. Although social desirability bias was associated with reports of greater joviality and lower sadness, it could not account for the effects of the positive and negative mood induction procedures. We conclude that these combined mood induction procedures can be used in online research to study happy and sad mood.
People’s moods vary at different times. For instance, about 50% of variance in negative affect in everyday life is due to within-person factors, including variation across moments and days . As daily life variability in affect predicts important health-related behaviors (e.g., sleep ), it is important to understand temporary fluctuations in affect. A common experimental approach to study mood is to employ mood induction procedures (MIPs) in which experimental stimuli are administered in a controlled fashion to alter people’s mood temporarily. Widely used examples of MIPs include presenting affectively-laden video clips, songs, or self-referential statements known as Velten statements . A meta-analysis indicated that MIPs on average produce about a one standard deviation change in mood compared to control procedures studies . However, there is substantial heterogeneity of effect sizes across studies, and a recent meta-analysis on internet-based studies failed to find support for the effectiveness of happiness MIPs administered online , which may be due to the diversity of MIPs. Several reviews have recommended video clips as they induce medium-to-large changes in positive and negative mood [3–5], but a handful of studies have observed large effect sizes for combined MIPs (e.g., reading Velten statements while listening to music; ). In this paper, we developed and tested combined MIPs administered online comprising video clips followed by music excerpts with Velten statements or closed eyes instructions.
Our aim was to create short Velten forms that could be used to quickly induce temporary changes in happiness and sadness and to develop and evaluate a set of neutral self-referent statements that could be used as a control condition. Our goal was to extract at least 15 statements with high positive valence ratings, 15 negative statements with high negative valence, and 15 neutral-self and 15 neutral-facts close to each other and to the midpoint of the bipolar valence scale.
As internet-based MIPs have been inconsistent in inducing the targeted moods , whereas laboratory-based MIPs that combine various induction techniques have yielded large effect sizes , we aimed to test combined MIPs online. In addition to seeking MIPs that could yield relatively large effects online, Study 2 tested whether Velten or closed eyes instructions were more effective when being presented with music following a video clip. We selected 60 Velten statements based on the ratings in Study 1. We reasoned that by selecting effective Velten statements based on Study 1 ratings, it would be informative to follow up on previous research , which did not find any significant difference between Velten and simple instructions to get into the targeted mood. We expected that positive MIPs would increase happiness and negative ones would increase sadness, but did not expect any changes in happiness or sadness from the Neutral MIPs or any differences between Velten and closed eyes. We pre-registered the study at aspredicted.org (https://aspredicted.org/dc7id.pdf).
These studies update the Velten literature by adding neutral self-referential Velten statements and providing valence ratings of 80 individual statements, which can be used for quick, standardized mood inductions. As we ranked the valence ratings of each Velten statement, only four statements obtained incongruent ratings. Based on the results of Study 1, we developed sets of 15 statements per condition: positive, negative, neutral-self, and neutral-facts. Study 2 integrated these sets together with standard video and song clips to form combined online MIPs of 8 min that could induce relatively large effects in internet-based settings. Compared to neutral conditions, positive MIPs successfully induced large increases in joviality (and medium-sized decreases in Sadness). Likewise, compared to neutral conditions, the negative MIPs successfully induced large increases in Sadness (and large decreases in Joviality). These effect sizes compare favorably to those observed in a previous meta-analysis on internet-based MIPs (Ferrer et al., 2015), suggesting that these procedures can be useful for future online research on mood. There was no support for an advantage of Velten statements over closed eyes instructions when combined with music (and following a video clip), despite confirming the effectiveness of each Velten statement in Study 1 and selecting the most effective ones for Study 2.