 While unitization and differentiation are converses, the one unifying and the other distinguishing, Goldstone and Byrge also conceive of them as “flip sides of the same coin” (2015: 823). This is because, as they put it, both unitization and differentiation “involve creating perceptual units…” (2015: 823). Regardless of whether the unit arises from the fusion or the differentiation of two other units, both instances of perceptual learning involve the creation of new perceptual units.