Research on issue ownership – parties’ reputation of competence in handling specific issues – has rapidly expanded over the past decade. While issue ownership has long been considered a stable attribute of parties, recent studies have documented the dynamic nature of individual voters’ perceptions of party issue competence and have demonstrated that voters who change their issue ownership attributions are more prone to change their party vote accordingly. Despite the electoral consequences of a voter’s changing issue ownership perceptions, little is known about the sources of such instability. So far, the emerging literature has mainly focused on the role of campaign information, but has neglected the role of individual-level factors. This paper tackles this gap and brings in the role of the accessibility of voters’ issue ownership perceptions. For voters with more accessible perceptions, it is immediately clear who the most competent party is, while voters with less accessible attitudes have to think longer before they can identify an issue-owning party. We contend that more accessible competence perceptions are more stable. Furthermore, this accessibility effect should be more pronounced for voters who do not identify with the party that they deem most competent, and for party-issue pairs that correspond to long-standing party reputations on the aggregate level (e.g. the Greens and the environment). Empirically, we measure the accessibility of voters’ issue ownership perceptions by survey response times. Our analysis of data from a multi-wave panel survey conducted in the framework of the Swiss Election Study (Selects) largely supports our expectations.