Ideology, for Althusser 'represents the imaginary relationship of individuals to their real conditions of existence' (cited in Stevenson 1995: 37). Ideology transforms human beings into subjects, leading them to see themselves as self-determining agents when they are in fact shaped by ideological processes.
Tony Bennett notes that since he represents all ideological forms as contributing to the reproduction of the existing system, Althusser comes 'dangerously close to functionalism', representing capitalist society as monolithic, and failing to allow for internal conflict (Bennett 1982: 53). Stuart Hall adds that in Althusser's theory it is difficult 'to discern how anything but the "dominant ideology" could ever be reproduced in discourse' (Hall 1982: 78). In Althusserian theory mass media texts 'interpellate the subject' whereas many current media theorists argue that the the subject projects meaning onto the media texts. For the notion of a 'struggle over meaning' one must turn to Volosinov and Gramsci. Althusser's influence has been held responsible by some critics for leading some of his followers into purely formalist readings of the signifying systems of mass media forms, neglecting their modes of production and reception. However, Althusser is 'the central conduit through which developments in structuralism and semiotics have both entered into and lastingly altered Marxist approaches to the media' (Bennett 1982: 53).
For useful general accounts of Althusserian Marxism see: Lapsley & Westlake 1988: 3-16; Gurevitch et al. 1982: 23-5; Bennett 1982: 51-3; White 1992: 168-9; Fiske 1992: 286-88.