 In the case of visual experiences, for example, it is frequently supposed that there is a range of visual qualia, where these are taken to be intrinsic features of visual experiences that (a) are accessible to introspection, (b) can vary without any variation in the representational contents of the experiences, (c) are mental counterparts to some directly visible properties of objects (e.g., color), and (d) are the sole determinants of the phenomenal character of the experiences. This usage of ‘qualia’ has become perhaps the most common one in recent years. Philosophers who hold or have held that there are qualia, in this sense of the term, include, for example, Nagel (1974), Peacocke (1983) and Block (1990).