As far as I can tell, experimentalism in 20th century British Fiction has been defined by the challenging social conventions through challenging literary conventions. That may seem simplistic since as English majors we tend to assume that the author's use of syntax and style is always reflective of the rest of the work, but the texts that we have read for this course have all been aimed at critiquing or examining something in society: "what is love?" in Women in Love; fascism and group-think in The Waves; social class and it's relation to language in Loving; the social standing of women in Voyage in the Dark. Molloy and The Golden Notebook challenged conceptions of madness: is pure madness somehow less insane than the madness of the system? Crash challenges our conception of how do we define humanity in a world where technology and cyborgism are becoming the norm.
Yet all of those themes can theoretically be explored through narrative alone. But every one of these texts takes full advantage of the very mechanics* of writing. In other words, the often amorphous message of the piece is carried in both the mechanics of the text as well as in the actual narrative.
While all good works of fiction use the mechanics of their writing in conjunction with providing the narrative, the books in this course are extremely aware of the relationship between mechanics and narrative. In different ways, every novel in this course used the challenging of literary and narrative conventions to emphasize the narrative's challenge social to conventions (specifically control, love, gender equality, normalcy). The reverse can also be true, in that the narrative social context also provides a critique of the literary conventions.
Woolf's constructions of characters in The Waves boiled them down to a collective, a supposed single unit (such as the goal of a fascist state), yet undermined that unity in the way each character provided their own separate perspective which ultimately could not be summed up by one ideology (Bernard/fascism).
Crash's fusing of sexuality (one of the most basic of human processes) with technology, is further emphasized by Ballard's clinical yet accurate use of the term "sex act,"** contrasted with terms like "make love" (a term which is inherently a metaphorical construct yet is somehow more natural). The conflict between what is accurate (or linguistically natural), and what the reader perceives as natural (but which is in fact a construct) brings the reader back to that central question of how do we define human in a world run by our technology (mechanically: how can artificiality be more "true" than the "natural").
While it is possible that my definition for experimental is too broad, since it sort of encompasses every work in which mechanics and narrative line up. The fact that the mechanical metaphor for the works is being delivered through internal critiques and discussions of literary conventions, I'd say that the fact that the narrative and mechanics are having two distinct conversations (narrative conventions and social conventions) yet keep both reflecting, critiquing, and changing each other, take the works beyond merely being symbolic, and into the realm of experimental.
*I am borrowing the term mechanics from the perspective of game-design. In game design the mechanics represent the way the various elements of play and their interaction, in a literary context this translates to something akin to the interactions of words, syntax, and narrative delivery-style.
**a fun game for Crash, every time Ballard says "sex act," imagine the voice of the generic nerd from Robot Chicken.