Prominent theories in cognitive and developmental psychology have posited that our perceptual sense of number, time, and space form a singular, domain-general representation. In this talk, I provide extensive evidence to suggest that these perceptual representations are distinct: children and adults show no correlations between number, area, density, time, etc., when domain-general factors such as working memory, response conflicts, and general developmental improvements are controlled for, saccadic trajectories show unique encoding algorithms for number vs. area, and individual differences in number perception uniquely predict formal mathematical abilities. But, critically, number, space, and time share a common representational format of noisy Gaussian tuning curves on independent scales, allowing for interactions between them in specific contexts: reasoning about perceptual confidence and learning to map number words to length and area. This independent-representational but shared-format view allows us to reconcile some traditional findings in the perceptual magnitudes literature while preserving the view of domain-specificity in the perception of number, time, and space.