Social nudges for vaccination: How communicating herd behaviour influences vaccination intentions.

OBJECTIVES: This Registered Report attempted to conceptually replicate the finding that communicating herd immunity increases vaccination intentions (Betsch, et al., 2017, Nat. Hum. Behav., 0056). An additional objective was to explore the roles of descriptive social norms (vaccination behaviour of others) and the herd-immunity threshold (coverage needed to stop disease transmission). DESIGN: An online experiment with a 2 (herd-immunity explanation: present vs. absent) × 3 (descriptive norm: high vs. low vs. absent) × 2 (herd-immunity threshold: present vs. absent) between-subjects fractional design. METHODS: Sample consisted of 543 people (aged 18-64) residing in the United Kingdom. Participants first received an explanation of herd immunity emphasising social benefits (protecting others) in both textual and animated-infographic form. Next, they were faced with fictitious information about the disease, the vaccine, their country's vaccination coverage (80% or 20%), and the herd-immunity threshold (90%). Vaccination intention was self-rated. RESULTS: Compared to the control, communicating social benefits of herd immunity was effective in increasing vaccination intentions (F(1,541) = 6.97, p = .009, Partial Eta-Squared = 0.013). Communicating the descriptive norm or the herd-immunity threshold alongside the herd-immunity explanation demonstrated no observable effect. CONCLUSION: Communicating social benefits of herd immunity increased self-reported vaccination intentions against a fictitious disease, replicating previous findings. Although this result is positive, the practical relevance may be limited. Further research into the effect of social nudges to motivate vaccination is required, particularly with respect to the recent pandemic context and varying levels of vaccine hesitancy.

The general fault in our fault lines.

Pervading global narratives suggest that political polarization is increasing, yet the accuracy of such group meta-perceptions has been drawn into question. A recent US study suggests that these beliefs are inaccurate and drive polarized beliefs about out-groups. However, it also found that informing people of inaccuracies reduces those negative beliefs. In this work, we explore whether these results generalize to other countries. To achieve this, we replicate two of the original experiments with 10,207 participants across 26 countries. We focus on local group divisions, which we refer to as fault lines. We find broad generalizability for both inaccurate meta-perceptions and reduced negative motive attribution through a simple disclosure intervention. We conclude that inaccurate and negative group meta-perceptions are exhibited in myriad contexts and that informing individuals of their misperceptions can yield positive benefits for intergroup relations. Such generalizability highlights a robust phenomenon with implications for political discourse worldwide.