An attribute that is not inherent in a phenomenon, inasmuch as the phenomenon can occur or exist without the attribute. For example, frequency (1) is a separable attribute of sound, because noise (1) is sound without frequency, whereas amplitude is not a separable attribute of sound, because without amplitude there can be no sound wave and therefore no sound. In the visual modality, saturation (1) is a separable attribute of colour, but lightness is not. See also separable stimulus dimension. Compare integral attribute.