Age-related differences in associative inference are larger than differences in direct associative memory

Inferential reasoning is an important cognitive ability that allows us to make connections across past experiences to make decisions in the face of novel information. Making an inference involves the ability to remember separate experiences with overlapping elements (direct memory), and the ability to make connections between those experiences (inference/indirect memory). While older adults are known to have a deficit for direct associative memory, less is known about potential age differences in inference. In the present study, we administered an associative inference task to healthy young (aged 18-30; n = 83) and older adults (aged 60+; n=80). We tested whether there is an age difference in inference abilities above-and-beyond age deficits in direct associative memory. Results showed that an age-related deficit in inference that was larger than for direct associative memory. This finding is consistent with inferences in both age groups being based largely on overlapping memories encoded individually and recalled simultaneously when inferences were required, with older adults having more difficulty with this process than young adults. We also found that older adults were more likely than young adults to show source confusion after having made a successful inference, which is consistent with older adults tending to integrate across related experiences to a greater degree than young adults. Thus, we find a clear age-related deficit in inference abilities above- and-beyond direct associative memory, with some evidence of age-related differences in both retrieval- and integration-based inference mechanisms.