Abstract:

In recent years, the nudging method of default options has been increasingly used to improve public behavior and increase the public approval of social policies. Default option setting is a tool of choice architecture. It involves setting a pre-selected option that takes advantage of people’s inertia, subtly increasing the likelihood that decision-makers choose this default option. Defaults are commonly framed in the opt-in system (without any default) and opt-out system (target option as a default). The frequencies at which the target option is of the target option is chosen are considerably higher in the latter, which is known as the default effect. Although a great number of studies have shown the default effect in various scenarios, the effectiveness of default nudge has been questioned by scholars and the public nowadays. For example, there are a series of studies that show that default option settings are ineffective or even counterproductive in promoting public behavior.
Given the dispute on the effectiveness of the default nudge method, the current study aims to systematically examine how effective defaults are and whether their effectiveness varies across culture (Eastern culture vs. Western culture), domains (money-related domain, health-related domain, and environment-related domain), behavioral motives (benefits self vs. benefits others; whether there is real financial consequence of choice), and experiment characteristics (type of dependent variables, time of publication, sample size, and type of experiment). We conducted a literature search and meta-analysis of 56 articles, covering 92 default studies (pooled n = 112, 212, range = 16 ~ 19992) that fitted our inclusion criteria. The meta-analysis revealed that opt-out defaults lead to more pre-selected decisions than opt-in defaults do (d = 0.59, t = 10.12, 95% CI = [0.47, 0.71], p < 0.001), indicating that default nudging has a considerable effect. Further analysis showed two factors that could partially explain when the defaults’ effectiveness varies. First, moderating analysis showed that cultural background moderated the effect of default nudging: the effect of opt-out system under Western culture performed better than that under Eastern culture (b = 0.44, 95% CI = [0.05, 0.84], p = 0.027). Second, the moderating analysis also revealed the moderating effect of consumer choice and health choice. The nudging effectiveness of the default option settings was relatively better in the field of consumer choice (b = 0.43, 95% CI = [0.15, 0.70], p = 0.002), also somewhat effective in the field of pro-environmental choice (b = -0.32, 95% CI = [-0.66, 0.02], p = 0.067), and weakest in the field of health domain (b = -0.32, 95% CI = [-0.42, 0.10], p = 0.233). Lately, the default effect was not influenced by motivational factors or experiment characteristics.
In conclusion, the current work-integrated findings in previous default-related studies and answered the questions regarding how effective the defaults are and when their effectiveness varies. The present meta-analysis covered 21 more studies than previous analyses and 5 more studies based on the Asian samples. In the 92 studies included in this meta-analysis, most showed a positive effect of default nudge on people’s behavioral change, and only a few studies found no significant or negative effects. The total default effect in our analysis was slightly lower than the results reported by Jachimowicz et al. (2018), but it still showed a medium-sized effect, indicating that the default nudge is indeed effective in promoting behavioral changes. Our finding provides a new conclusion for the studies of the effectiveness of the default effect, and reveals the moderating effect of cultural background for the first time, which may help us to better understand whether the defaults are effective and when to use the defaults.

Key words: default options, nudge, meta-analysis, opt-out, opt-in