  Attempts to define the nature of these cognitive aspects and their  cognitive function are the origin of a lengthy dispute that cuts  across doctrinal and scholastic boundaries. Thus Dignāga and  Dharmakīrti follow the Sautrāntika and Yogācāra  Buddhists who maintain that cognitive awareness has an aspectual  character: that is, cognition takes the form of whatever object it  cognizes (a position known as  sākārāvāda). The Vaibhāṣikas  and some Mādhyamikas take the opposite view: consciousness is  mirror-like in its nature, reflecting an object without being  modified by it (cf. Kajiyama 1965, 428; Moriyama 1984; Tillemans  1990, 41f). The representational model of cognition adopted by the  epistemologists resembles Western variants of representationalism as  proposed by, among others, Descartes and Locke.