'Who; Says what; In which channel; To whom; With what effect?' The above communication model was given by

The model asking Who, says what, in which channel, to whom and with what effect was given by Harold D. Lasswell.

Its five questions map neatly onto communicator, message, medium, audience and effect.

Aristotle's model, by contrast, rests on the speaker, the speech and the listener alone.

Shannon and Weaver's model is the mathematical one built around signal, channel and noise.

Osgood and Schramm gave the circular model stressing mutual encoding and decoding between two parties.

Lasswell first set out this formula in 1948.