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From Clustering to Path Length: Neural Correlates of Semantic Search Organisation
Poster Session F, Friday, October 2, 2:45 - 4:45 pm, Wangari Maathai
This poster is part of the Sandbox Series.
Bedia Vidua1, Valentina Alimenti1, Lara von Dombrowski1,2, Katalin Havas1, Johanna Kißler1,2,3, Martin Wegrzyn1,2; 1CRC Linguistic Creativity in Communication, Bielefeld University, Bielefeld, Germany, 2Department of Psychology, Bielefeld University, Bielefeld, Germany, 3Center for Cognitive Interaction Technology, Bielefeld, Germany
Semantic verbal fluency tasks provide a useful behavioural measure of how individuals navigate through semantic memory (Benigni et al., 2021). Within this framework, clustering and switching provide useful indicators of semantic search organisation, reflecting both the structure of semantic associations and the control processes involved in navigating the mental lexicon (Troyer et al., 1997). Flexible retrieval exploration of semantic memory has been linked to individual differences in cognitive flexibility and creativity (Kenett et al., 2014; Nusbaum & Silvia, 2011). To investigate whether key aspects of semantic search organisation are reflected in neural activation patterns during the processing of self-generated words, the present ongoing study combines a verbal fluency paradigm with functional magnetic resonance imaging (fMRI), thereby linking behavioural and neural variation in word retrieval. To date, ten German-speaking participants (data collection ongoing) have completed both a behavioural and an fMRI session. In the behavioural session, participants generated 30 German words each for two semantic categories ("animals" and "hobbies") and three emotion categories ("emotions", "what evokes positive/negative feelings?"). These individually generated word lists served as stimuli for the subsequent fMRI experiment. During fMRI, participants were first presented with their own words in a randomized order within each category (passive run). In a second (active) run, the same words were presented in the original generation order, and participants rated their autobiographical relevance. To assess individual category structure, participants then completed a similarity-based spatial arrangement task (“Arena task”), in which they positioned their words by category inside a circular space according to perceived similarity (Hout et al., 2013). Based on inter-item distances, a path length was defined as the summed distance between consecutively generated words in the individual’s semantic space. The analyses focus on category-specific contrasts between the semantic categories "animals" and "hobbies". Descriptive behavioural results indicate faster word production for "animals" than for "hobbies", suggesting differences in retrieval dynamics at the category level. This may indicate that "hobbies" are represented in a more diverse semantic space than "animals". The study uses path length to examine semantic distance across transition types, from the broader distinction between within-cluster and between-cluster transitions to a more detailed distinction between cluster switches and hard switches as defined by Abwender et al. (2001). As not all switches are cognitively equivalent, cluster switches are distinguished from hard switches, with the former reflecting transitions between adjacent or overlapping clusters and the latter referring to transitions to or from single words (Abwender et al., 2001). This approach makes it possible to test whether different types of semantic transitions reflect distinct modes of search through semantic space and the control processes involved in navigating it. At the neural level, longer path lengths, especially those associated with between-cluster transitions and hard switches, are expected to relate to stronger recruitment of regions involved in semantic search and controlled semantic retrieval, including left inferior frontal and posterior temporal regions (Lambon-Ralph et al., 2017).
Topic Areas: Meaning: Lexical Semantics, Language Production