Westley–MacLean Model (Bruce Westley & Malcolm MacLean, 1957)

Extends the interpersonal loop to mass communication by inserting a gatekeeper role C between events and audience. Advocate A wants to reach audience B about objects of orientation X; channel/gatekeeper C selects and relays which X's ever reach B, with feedback loops f_BA, f_BC, f_CA.

Which piece of Shannon it adds back: the editorial filter — the media/platform channel is not a neutral pipe but a selector deciding what B gets to perceive at all. And C is non-purposive: it serves B's needs, not just A's.

Transfer. For agent content the gatekeeper C is now the feed algorithm, the aggregator, the "for you" ranker. You are advocate A; you never reach reader B directly. Optimizing the message for B while ignoring C's selection criteria means B never sees it — being seen reliably is being legible to C first. And because C's mandate is to serve B, content that only advances your goal gets filtered out before the audience exists.

Kin: models, schramm-model, two-step-flow, being-seen-reliably, growth-stages