The reluctant allure of neurotechnologies across cultures

Wearable neurotechnologies collect brain data outside clinical settings, raising increasing concerns about privacy and data sharing among academics and policymakers. But are these concerns shared by the public? And if so, do they reflect the novelty of the technologies, the perceived accuracy of brain-derived inferences, or the special symbolic status people attach to the brain itself? We tested these possible explanations in four preregistered experiments (N = 627) conducted in the United Kingdom, Germany, Spain, and the United States. Participants evaluated scenarios in which emotional states were inferred using one of three data sources: brain activity (EEG), heart rate, or pupil size. The scenarios varied in data recipient (public or private institutions) and data sharing purpose (personal or collective). Participants rated the acceptability of sharing each data type, as well as the perceived reliability of and familiarity with each method. Across countries and contexts, participants were consistently more reluctant towards sharing brain than heart data. This effect did not track perceived reliability: heart data were often judged as equally or more reliable than brain data. Familiarity with the technologies increased overall acceptance but did not explain the specific reluctance to share brain data. For the U.S., lower willingness to share brain data was specifically associated with viewing the brain as central to personal identity. These findings show that neurotechnologies are treated as uniquely sensitive not because they are seen as more informative, but because the brain is perceived as closely tied to the self.