There has been a recent shift in theoretical approaches to thinking about audiences due to the introduction to performance theory into the art theory canon. A typical text is Performance Theory By Richard Schechner. If using these theories you can think about the role of the artist as being a type of performance, therefore the audience is seen much more within the context of a theatrical performance. For instance within the conventions of theatre we 'suspend disbelief' i.e. we read the events as they unfold outside of 'reality'. You could therefore suggest that a similar situation occurs when an artists stages an exhibition. The artist plays out a role, that of the artist, and with that comes all of the conventions that that role brings with it, (think of how the artist is categorised/played in films such as 'Lust for Life' or Hancock's 'the Rebel'.) The audience then brings with it an expectation of how the artist should operate. Maurizio Cattelan's work can easily be read within this context.
The opening of an exhibition itself can therefore be seen as part of the ritual of engagement and the audience as participants. This can be opened out to the whole art world, where curators, gallerists, dealers etc all play defined roles. See http://edwardwinkleman.blogspot.com/ for an interesting art world blog.

Catchword: gallerist
Part of speech: n.
Quotation: A fashionable new word is bubbling up in the New York art scene: gallerist, as a substitute for art dealer. Not, of course, just any art dealer. A gallerist is directly involved with the care and feeding of artists, rather than with the quick turnover of art objects.…Some suggest it derives from the French galeriste, long used by top gallery personages in France to distinguish themselves from the mere marchand de tableaux, or picture merchant. Others say it came from Germany, where galerist or galeristin denotes, respectively, a male or female gallery owner.