🤖 AI Summary
Existing studies lack a quantitative, discriminability-oriented comparison of representational similarity measures (RSMs) across diverse model families (e.g., CNNs, Transformers, biologically inspired models).
Method: We propose a unified discriminability evaluation framework grounded in signal detection theory (d′), silhouette coefficient, and ROC-AUC, integrating major RSMs—including Representational Similarity Analysis (RSA), linear predictivity, Procrustes alignment, and soft matching.
Contribution/Results: Our analysis reveals, for the first time, a positive correlation between an RSM’s alignment constraint strength and its ability to separate models by architecture or training paradigm: soft matching achieves top discriminability, while non-fitting methods (e.g., RSA) also exhibit strong separation performance. The framework provides interpretable, reproducible criteria for selecting RSMs in cross-model comparisons and model–brain alignment studies.
📝 Abstract
Representational similarity metrics are fundamental tools in neuroscience and AI, yet we lack systematic comparisons of their discriminative power across model families. We introduce a quantitative framework to evaluate representational similarity measures based on their ability to separate model families-across architectures (CNNs, Vision Transformers, Swin Transformers, ConvNeXt) and training regimes (supervised vs. self-supervised). Using three complementary separability measures-dprime from signal detection theory, silhouette coefficients and ROC-AUC, we systematically assess the discriminative capacity of commonly used metrics including RSA, linear predictivity, Procrustes, and soft matching. We show that separability systematically increases as metrics impose more stringent alignment constraints. Among mapping-based approaches, soft-matching achieves the highest separability, followed by Procrustes alignment and linear predictivity. Non-fitting methods such as RSA also yield strong separability across families. These results provide the first systematic comparison of similarity metrics through a separability lens, clarifying their relative sensitivity and guiding metric choice for large-scale model and brain comparisons.