Kim, J. (1971). Materialism and the criteria of the mental. Synthese22, 323–345 doi:10.1007/BF00413431
[Citing Place (1956)]  
Citing Place (1956) in context (citations start with an asterisk *):
* Even the materialist who asserts that all mental events are physical events in the brain must begin with some reasonably clear and determinate concept of what a mental event is. How else would anyone, including the materialist himself, know what he is talking about? Thus, J. J. C. Smart begins his exposition and defense of the identity theory of mind with what seems at least like an informal characterization of his subject matter:
Suppose that I report that I am having an orange-yellow roundish after-image .... There seems to be some element of 'pure inner experience' which is being reported, and to which only I have direct access. You can observe my behaviour, but only I can be aware of my own after-image or my own pain.... Note 1: Philosophy and Scientific Realism, London 1963, p. 89.
And U. T. Place, another prominent proponent of the identity theory, follows a similar route:
For our present purposes, however, I shall assume.., that statements about pains and twinges, about how things look, sound, and feel, about things dreamed of or pictures in the mind's eye, are statements referring to events and processes which are in some sense private or internal to the individual of whom they are predicated. Note 2: 'Is Consciousness A Brain Process?', reprinted in John O'Connor (ed.), Modern Materialism: Readings on Mind-Body Identity, New York 1969, p. 22.
These characterizations of mental events are similar in that they both make use of such essentially epistemic concepts as privacy and direct accessibility; and when Smart and Place claim that mental events are brain events, they must be understood as claiming that events with these properties are brain events. And unless the existence of mental events is denied, which is not likely, these materialists are committed to the thesis, which might seem absurd, that certain physico-chemical events inside the skull have the properties of privacy and direct accessibility.
As the quotations from Smart and Place at the outset of this paper indicate, most philosophers now seem to favor some sort of epistemic criterion; the concept of mental seems today more closely associated with such notions as 'privileged access', 'direct awareness', and 'privacy' than with the more abstract notion of intentionality and the basically unintuitive notion of nonspatiality. And the focus of philosophical discussion, at least as it concerns the question of materialism, too seems to have shifted from the rational and cognitive aspects of the mental to the phenomenal and affective aspects. [...]