 Though it is possible for a sense-datum theorist to accept this, a more popular position has been one on which we still have some form of perception of the world, just not direct perception. That is, the sense-datum theorist can say that we indirectly perceive ordinary objects: we perceive them by being directly presented with sense-data. A sense-datum theorist who says this is known as an indirect realist or representative realist (see the entry on  epistemological problems of perception).  The task for such a sense-datum theorist is to spell out how the direct presentation of sense-data can lead to indirect perception of ordinary objects. This is something early sense-datum theorists pursued by asking how sense-data are related to ordinary objects. A theorist who denies that we perceive mind-independent objects at all, directly or indirectly, but only sense-data construed as mental entities, is known as a phenomenalist or an idealist (see Foster (2000), see Crane and Farkas (2004: Section 2) for an introduction to the subject; and the entry on  idealism).