Age differences in the decision information search: The roles of task complexity and task relevance

•Older adults perform a more thorough decision search than younger adults.•People are able to allocate more effort to address increasing task complexity.•Task relevance mainly impacts search pattern, and its effect varied by age.•Task complexity and task relevance might act independently in information search. A high task complexity may reduce or prompt people’s decision to search for information, and a high task relevance might stimulate a systematic search, but whether these factors interactive and whether their effects vary by age remain unknown. Therefore, we used a process-tracing program to investigate information searches by 58 younger and 60 older adults related to high- and low-relevance decisions of varying complexity. Older adults searched for decision-related information more thoroughly than younger adults, suggesting that increasing age may not be linked with information-minimizing searches. When the task complexity increased, both age groups showed greater search engagement and more systematic searches, suggesting that people evaluate task demands and allocate more effort to address increasing task complexity. People preferred systematic searches for high-relevance decisions, whereas older, but not younger, adults maintained this pattern for low-relevance decisions. Task complexity and task relevance function independently in the decision-related information search.