Generalization in Older Adults: Age Effects in Memory-Based Inference

Abstract

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 that have some degree of overlap (direct memory), and the ability to make connections between the elements based on their overlapping content (inference/indirect memory). While older adults are known to have a deficit for direct memory, less is known about potential age differences in making inferences. In the present work, I administered an associative inference task to both young (n = 83) and cognitively healthy older adults (n=80) with a first aim of understanding the degree of age differences in both direct memory and inference performance. Results showed that while older adults performed worse overall compared to younger adults, they were still able to find above chance success with memory for both direct and indirect pairs. As a second aim, I sought to clarify what inference mechanism may be utilized by older adults to make inference decisions. Results indicated that there was a greater cost of inference relative to direct memory in both age groups, with an especially large cost in older adults. This finding is consistent with inferences in both age groups being based largely on overlapping memories being encoded individually and recalled simultaneously when inferences were required, with older adults having more difficulty with this process than young adults. However, I also found some evidence that older adults were more likely than young adults to show source confusion after having made a successful inference, which would support the hypothesis that older adults tend to integrate across related experiences to support inference rather than keeping overlapping memories separated. Thus, while older adults showed a clear cost to making inferences compared to remembering direct items, it remains unclear which inference mechanism they rely on to arrive at these decisions.