This dissociation of pathways for visual processing in non-human primates has also been supported in human subjects with PET studies, suggesting that there may be similar specific pathways that analyse such features as colour, motion and location (Corbetta et al., 1991; Haxby et al., 1991; Zeki et al., 1991; Horwitz et al., 1992; Jonides et al., 1993; Grady et al., 1994).