Prevalence-induced concept change describes a cognitive phenomenon whereby judgements about concepts shift as the prevalence of exemplars of that concept changes. For instance, in a task where people have to judge whether the colour of an ambiguously-coloured dot is blue or purple, if the frequency of objectively blue dots in the environment decreases,
people judge more dots to be blue than they did initially. While this phenomenon has been explored in young adults, it is unclear how it affects older adults. Past work suggests that older adults simultaneously rely less on internal representations, but that they also tend to perseverate more on cognitive tasks. Thus, the question arises: Do older adults outsource control and their
decisions become more susceptible to change or are they more rigid in their judgements than younger and resistant to prevalence-induced concept change?

In the current study, we explore how prevalence-induced concept change affects older adults’ lower-level, perceptual, and higher-order, ethical, decision-making. We find that older adults are less sensitive to prevalence-induced concept change than younger adults across both
domains. An exploratory analysis is conducted on response times to help elucidate the mechanism(s) underlying these differences. These analyses demonstrate that older adults respond more slowly than younger adults in both tasks. We offer two interpretations of this finding, both with implications for prevalence-induced concept change research more broadly: general slowing and/or a speed-accuracy trade-off. Overall, our results suggest that older adults’ judgements about concepts may be less flexible than younger adults’ when faced with a changing world.