Number adaptation: Reply

Adaptation is a ubiquitous property of perceptual systems, increasing sensitivity to change and allowing them to operate over a large dynamic range. The number sense, like most other perceptual systems, is adaptable. Yousif et al. (2024) challenge the existence of number adaptation, offering an alternate explanation that they term the "old news hypothesis". Here we consider the major evidence advanced for their theory and show that, while their predicted effects may reach statistical significance, they are far too small to begin to explain the robust phenomenon of adaptation. We also highlight a series of studies using fMRI, EEG, pupillometry and psychophysical techniques that support the existence of adaption, and are inconsistent with "old news". We conclude that number adaptation, while not fully understood, does indeed exist, and remains an invaluable concept for understanding the number sense.