Is it because of the potential disruption of articulable meaning that Hitchcock's heroines must have hair that is so calculated, controlled--semiotic systems of spray and follicle and pin that do not take part in the filmic "third meaning" but rather are part of the symbolic universe of the film? In effect, this hair is "facialized". We can say, in regards to this avoidance of the trauma of the filmic (through his adaptation of novels and the rigid predictive mastery of the continuity script that made the actual filming seem boring to him) that Hitchcock is at best a novelist, at worst, an accountant. When "filmic" moments happen in his films, they are not accidental, but calculated to represent clearly that which falls out of signification (the Dali dream murals of Spellbound, the psychedelic sequences of Vertigo). Even love--as floating signifiance--has no locus of animation, except, perhaps, if one has a surrealist love of decor and detailed mise-en-scene, or a fetishist's eye (although even these loves seem to be programmed into what Barthes calls the "obvious" system of meaning).
It's telling that, when Hitchcock's characters kiss, the kiss is filmed as if it had leapt outside of the space-time of the film (the changed camera speed of the kiss in Rear Window, the banal non sequiturs surrounding the kiss in Marnie, the 360 degree space-collapsing glide around the last kiss of Vertigo). . . a bit of legerdemain in the service of pin-pointing, containing and defusing the thing that disrupts the ledgers.