The psychophysics of compositionality: Relational scene perception occurs in a canonical order

We see not only objects and their features (e.g., glass vases or wooden tables) but also relations between them (e.g., a vase on a table). An emerging view accounts for such relational representations by positing that visual perception is compositional: Much like language, where words combine to form phrases and sentences, many visual representations contain discrete constituents that combine in systematic ways. This perspective raises a fundamental question: What principles guide the compositional process for relational representations, and how are these representations built over time? Here, we tested the hypothesis that the mind constructs relational representations in a canonical order. Inspired by a distinction from the cognitive linguistics tradition, we predicted that 'reference' objects (large, stable, or physically controlling objects; e.g., tables) take precedence over 'figure' objects (e.g., vases) during scene com- position. In Experiment 1, participants who were instructed to arrange items to match linguistic descriptions (e.g., "The vase is on the table", "The table is supporting the vase") consistently placed reference objects first (e.g., table, then vase). Experiments 2–5 extended these findings to visual recognition itself: Participants were faster to verify a description when the reference object appeared before the figure object in the scene, rather than vice versa. This Reference-first advantage emerged rapidly (within 100 ms), persisted in a purely visual task, and could not be explained by differences in object size or shape. Together, our findings reveal psychophysical principles underlying compositionality for object relations in visual processing: the mind builds relational representations sequentially, respecting each element's role.