What does the inset play (Act 3, Sc ii) in Shakespeare's Hamlet tell us about the theme of deception?

The play-within-a-play highlights the feeling of paranoia built up throughout Hamlet. In performance, it makes the audience highly aware of their perspective as witnesses to both truth and lies. The whole scene forces the audience to become aware of the fact they are watching actors (who are also watching actors), which is its own kind of benevolent lying. The inset play is a dumbshow, containing no dialogue: perhaps suggesting that speaking of any kind is a type of lying. Indeed, Hamlet says as much earlier in the play: he must "unpack [his] heart with words", unable to act. (Act II, Sc 2) There is a suggestion that by speaking and not acting he is being self-deceptive. Confronted by Claudius before the play begins, Hamlet pretends to be mad in order to reveal the truth. Asked how he is, Hamlet replies " Excellent, i' faith; of the chameleon's dish: I eat / the air, promise-crammed." (Act III, Sc 2) Although this is nonsense, Hamlet draws on the semantic fields of deception and falseness, with words like "chameleon" and the suggestion that the air is "cramm'd" with invisible (therefore empty) promises. The theme of deception and surveillance was common in Shakespeare's time, as Queen Elizabeth kept an elaborate spy network under Francis Walsingham to hunt down Catholics and political revolutionaries.