Causes and Consequences of Representational Similarity in Machine Learning Models

Numerous works have noted similarities in how machine learning models represent the world, even across modalities. Although much effort has been devoted to uncovering properties and metrics on which these models align, surprisingly little work has explored causes of this similarity. To advance this line of inquiry, this work explores how two factors—dataset overlap and task overlap—influence downstream model similarity. We evaluate the effects of both factors through experiments across model sizes and modalities, from small classifiers to large language models. We find that dataset and task overlap are positively associated with higher representational similarity across many of our settings, with clear evidence in vision/language classification and weaker trends in language generation experiments. Finally, we consider downstream consequences of representational similarity, showing that greater similarity is associated with increased vulnerability to transferable adversarial attacks in vision models.