I found myself wondering the other day whether the theatrical aside is an essentially comic device. The occasion was the first night of Simon Godwin's new production of Strange Interlude at the National Theatre (pictured), a positive fiesta of theatrical asides. On the evidence of that evening alone, there wouldn't have been much doubt about the answer. The theatrical aside, you would have concluded, is irresistibly comic in its nature, a rug-pulling bit of verbal slapstick which had the audience in stitches. This might have come as a surprise to Eugene O'Neill, who I don't imagine ever expected his socially daring drama to be hailed as "the laff-riot of 1928" when it was first produced on Broadway. But it seemed intentional in London. And the mechanism of the comedy involved isn't very complicated when you think about it. Someone says something in the imaginary public space of the drama – something bland or grand. And then they immediately contradict it in the real public space of the theatre.

The contradiction alone is funny, in its exposure of the contrast between how we like to appear and how we are. Think of the subtitle scene in Annie Hall, where Woody Allen's laboriously intellectual remarks conceal the fact that he's wondering what Annie would look like naked. But in the theatre there's something more, a friction between two overlapping spaces. No one expects the characters on screen to be aware of the subtitles that appear in front of them. But the convention of the aside is trickier, involving as it does the raw material of theatre itself. Can't they hear what she's just said, we think, however sophisticated we are about the conventions of heard and unheard speech. And that makes the contradiction even funnier. It happens with quite dark and serious asides, too. Think of Iago in Othello, sharing with us the real nature of his thoughts – and how that can stir a nervous laughter in an audience, simultaneously appalled and delighted that they're in the know about the thing.

One thing that Strange Interlude did underline is that when the aside is what you might call a direct aside – aimed squarely into the auditorium – the effect is much funnier than if it's the rendition of a private inner thought. Godwin's decision to have all his characters speak their inner thoughts directly at us, as if aware of our presence and our response, also accentuated the comedy. If you're being talked at, after all, it is only polite to give some indication that you're listening. So when a character gives an anguished yelp at the cosiness of his family nickname (a kind of running gag in the play), we chuckle to show we recognise his exasperation. Had he muttered the same lines inwardly, their bleakness could be observed in silence. Even if you wished to preserve anguish in a direct aside, you might be hard-pressed. What noise would you make to acknowledge pain? It's too awkward. It's easier to giggle.

The word "aside" itself is a kind of clue to how these things should work, I think. Who is it aside from? The other characters on stage, surely. But if that's true, it seems to sideline the audience. Aren't we meant to be central to the occasion, even if we're central in an unacknowledged space? "Aside" tells you that these remarks are best directed into some third space in the auditorium, an anomalous place which swallows the sound from those on stage but allows us to overhear. And, unless you want the audience to laugh, it's probably best to avoid any sense that the characters uttering the aside are aware they're being overheard.

Then again, it may be that it's Strange Interlude that is irretrievably comic, rather than asides themselves – an experiment that was worth trying once as a means of getting closer to the tragedy of life, but which is of most interest now because of the categorical nature of the results that came back.

The riot where life became art

The word "iconic" is so overused it's best to avoid it altogether. But I'd almost make an exception for that photograph of a Turkish protestor in a red dress being pepper-sprayed. Everything worked to transform a momentary incident into an emblem of the cause: the dynamism of both poses – the policeman semi-crouched as he sprays, the victim turning away in shock; the fact that her dress echoes the colours of the Turkish flag, while the black of his uniform is the home colour of state oppression; the fact that the assault is drawn in the air by that plume of off-white gas. It's not life. It's a poster.

Here's one to get your teeth into...

I don't much care for vampire movies, but I liked Neil Jordan's Byzantium, partly for its studiously grotty settings, but also because Saoirse Ronan makes a compellingly anaemic member of the undead. As always, though, I got snagged in the technicalities. Here's one I just can't work out. Ronan plays the teenage daughter of Gemma Arterton, the two of them trapped by their condition in a perpetual hell of sulky mutual resentment. But how did Ronan's character get to be teenage? If she was born a vampire baby and vampires never age, wouldn't Arterton still be carrying her round in a baby-sling? Oh, and how exactly do you wean a vampire?