A cross-modal social-semantic space explains patterns of social-knowledge impairment in semantic dementia

Poster Session A - Saturday, April 13, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Claire Peplinski¹, Y. Ivette Colón¹, Matthew Rouse², Matthew Lambon Ralph², Timothy Rogers¹; ¹University of Wisconsin - Madison, ²University of Cambridge

Identifying loved ones, peers, and social groups hinges on the semantic organization of social concepts. Studies of patients with semantic impairments can therefore illuminate how social knowledge is structured in the mind and brain. In this study, we analyze error patterns from a social word-picture matching test conducted on 21 patients diagnosed with semantic dementia (SD), and compare these results to a semantic organizational map of the same test items captured from a separate group of age- and culture-matched individuals. The patient word-picture matching data suggests that SD patients exhibit more robust retention of gender compared to age information, with age-related errors correlating with linear age distance from concept words. Are these error patterns consistent with semantic similarity accounts of concept degradation? To generate a conceptual space for comparison, 49 older adults in the UK completed a triadic judgment task on the same set of test words and images. From these judgments we computed a two-dimensional embedding representing the relative similarity of each item. Distances between items in the embedding reflect error patterns in SD: gender-matched items are closer to probed concept words than age-matched items, and age-related items become increasingly distant from concept words as semantic age increases. Overall, we demonstrate that for a set of social items, patterns of information degradation in SD are such that patients retain gender information over age information, age information degrades with distance in age, and this relationship observed in patient data corresponds to distances within a conceptual space computed from healthy adults.

Topic Area: EMOTION & SOCIAL: Development & aging