Mechanisms of semantic composition in older adults: control, semantic processing, and imagery

Introduction Semantic composition is the ability to create meaningful novel concepts from familiar concepts. This can be achieved through a set of cognitive abilities that vary across individuals. As aging affects semantic networks in complex ways, examining how older adults experience the process of combining concepts can clarify which cognitive abilities contribute to maintaining flexible conceptual thinking. Methods In this study, 87 healthy older adults and a comparison group of 83 younger adults completed a semantic composition task, along with tasks measuring individual variation in cognitive processes hypothesized to underlie semantic composition: semantic processing, cognitive control, divergent and convergent creative thinking, and visual imagery. Results In older adults, ease of semantic composition (in the form of conceptual combination) was predicted by cognitive control abilities, particularly when combining ambiguous word pairs that require resolving competing interpretations. In addition, older adults with stronger semantic processing and more vivid visual imagery found conceptual combination easier, with visual imagery especially benefiting attributive combinations. In younger adults, by contrast, ease of combining was more selectively related to cognitive control, with less evidence that semantic processing or imagery contributed in the same way. Discussion These findings demonstrate that the experienced ease of semantic composition in older adults reflects contributions from multiple cognitive mechanisms, varying by combination type, to maintain the capacity for conceptual flexibility.