Similarity and Representations

Aspects of Similarity in Natural and Artificial Minds

Humans construct useful representations to support adaptive behavior in high-dimensional sensory environments. Understanding the structure of those representations has been at the center of decades of psychological research. Human similarity judgments provide an effective way for characterizing the structure of representations by densely mapping the perceived relations between pairs of stimuli. This idea propelled a fruitful research program that yielded many classic results in the literature such as Shepard’s universal law of generalization, Tversky’s feature model, the helical representation of pitch, and multidimensional scaling analysis.

Despite its success, the similarity research program is not complete, in part because central results such as the universal law of generalization are based on low-dimensional artificial stimuli and small sample sizes that severely limit their generalizability, and in part because recent methodological advances such as the development of large language models, contrastive training, and adaptive experiment designs unlock new sets of questions that were simply not feasible before.

In this set of projects I combine the similarity-based approach with large-scale adaptive experiments, modern machine learning, and Bayesian modeling to address questions pertaining to three key aspects of representations: (i) Scaling: To what extent does representational structure generalize to naturalistic and ecologically valid tasks? (Marjieh et al., 2024; Marjieh et al., 2024) (ii) Alignment: How much of our cognitive representations can be recovered from language? (Marjieh et al., 2024; Marjieh et al., 2023; Marjieh et al., 2025) and (iii) Abstraction: What form of similarity can support learning abstract representations in humans and machines? (Marjieh et al., 2025)

References

2025

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    What is a Number, That a Large Language Model May Know It?
    Raja Marjieh, Veniamin Veselovsky, Thomas L. Griffiths, and 1 more author
    arXiv preprint arXiv:2502.01540, 2025
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    Learning Human-Aligned Representations with Contrastive Learning and Generative Similarity
    Raja Marjieh, Sreejan Kumar, Declan Campbell, and 4 more authors
    arXiv preprint arXiv:2405.19420, 2025

2024

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    The universal law of generalization holds for naturalistic stimuli.
    Raja Marjieh, Nori Jacoby, Joshua C Peterson, and 1 more author
    Journal of Experimental Psychology: General. Selected as Editor’s Choice , 2024
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    Pitch is Not a Helix: Probing the Structure of Musical Pitch Across Tasks and Experience
    Raja Marjieh, Thomas L. Griffiths, and Nori Jacoby
    bioRxiv, 2024
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    Large language models predict human sensory judgments across six modalities
    Raja Marjieh, Ilia Sucholutsky, Pol Rijn, and 2 more authors
    Scientific Reports, 2024

2023

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    Words are all you need? Language as an approximation for human similarity judgments
    Raja Marjieh, Pol Van Rijn, Ilia Sucholutsky, and 4 more authors
    In The Eleventh International Conference on Learning Representations, 2023