Driven by trust? Social norms increase trust in shared autonomous public transport

Public adoption of novel transport technology depends on the willingness of potential users to engage with unfamiliar systems. Trust is a key determinant of this willingness, yet little is known about how trust in shared autonomous vehicles (SAVs) can be shaped. The current pre-registered study investigates to what degree trust predicts the intention to use SAVs and whether static and dynamic social norms can influence the degree of trust in SAVs. Static norms convey the current consensus in a population, while dynamic norms highlight that attitudes or behaviors are changing over time. An online experimental survey was conducted in which participants (n = 1,032; n = 630 after filtering) were randomly assigned to one of three conditions: control, static norm, or dynamic norm. Each condition presented distinct normative statements embedded in informative vignettes about SAVs. The moderating effect of propensity to trust (interpersonal and automation-specific) on the relationship between normative framing and subjective trust was also examined. One-way ANOVA and regression analyses revealed that both static and dynamic normative framings led to significantly higher subjective trust in SAVs compared to the control group. No significant difference was found between the two normative conditions. Propensity to trust (both interpersonal and automation-specific) had direct positive effects on subjective trust but did not moderate the effect of normative framing. Safety evaluation emerged as the strongest predictor of subjective trust. Subjective trust, in turn, was strongly associated with intention to use SAVs. These findings indicate that norm-based interventions providing social cues about others’ trust can effectively shape public attitudes toward SAVs, even in the absence of firsthand experience. However, safety perceptions remain paramount, suggesting that normative strategies should complement, rather than substitute for, efforts to demonstrate and communicate the safety of autonomous public transport.