Schedule of Events | Symposia

Understanding the representational geometry of psychological and neural spaces across multiple similarity dimensions.

Poster Session F - Tuesday, April 1, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Johan Alejandro Gamba¹ (j.gambasegovia@ufl.edu), Vincent Taschereau-Dumouchel², Megan A. K. Peters³, Brian Odegaard¹; ¹University of Florida, ²University of Montreal, ³University of California Irvine

Assessing similarities between objects is a fundamental cognitive process for humans. Multivariate neuroimaging techniques like Representational Similarity Analysis (RSA) have advanced our understanding of neural activation patterns underlying conceptual distances. In our study, we explored the relationship between eight psychological similarity dimensions and fMRI voxel-based RSA matrices across 11 regions of the ventral pathway and prefrontal cortex in Spanish- and English-speaking populations. Participants rated similarities of object pairs (280 in total) based on eight properties (general similarity, animacy, shape, color, category, dissimilarity, preference, and fear). We compared these behavioral ratings to neural data, employing metrics such as correlational distance (c.d.), c.d. post-Fisher transformation, and cosine similarity, alongside Pearson, Spearman, and Kendall Tau correlations, to identify amplified or generalized features across metrics. Our results revealed a behavioral representational distinction between “object-based” dimensions (e.g., shape) and “subject-based” ones (e.g., preference). Object-based properties showed a consistent representational geometry, whereas subject-based properties exhibited differences that modulated their alignment with neural data. Behavioral categories like “general similarity,” “color,” and “shape” were highly correlated with neural representations, particularly in occipital and fusiform regions. However, results were influenced by noise ceiling limits of each region of interest. Consequently, our results suggest a higher granularity in sensory cortices compared to multimodal areas and also inform methodological considerations when contrasting results across regions. Overall, our findings highlight consistent cross-population relationships between psychological and neural representational spaces, providing insights into how object-based and subject-based dimensions are encoded across different brain regions.

Topic Area: PERCEPTION & ACTION: Vision