The way people absorb and process politically relevant information is central to their subsequent political behaviour (in terms of turnout and vote choice). Nonetheless, little is known about how young voters – who might be more impressionable than more experienced voters – respond to the provision of such information. In this article, we design a between-subject randomised controlled trial that exposes a sample of university students to positive, neutral or negative information about central government performance before the 2017 Portuguese local elections. We find that young voters update their perceptions more when exposed to negative news. This negativity bias is stronger for first-time voters. We also find that negative information significantly affects turnout of initially undecided young voters. Our results imply that sensitivity to information is heterogeneous and that some young voters may be prone to manipulation through the provision of negative news.