Laugh, Lilian Baylis Studio, London<br/>The Art of Laughter, Linbury Studio, London

Like it or not, Frau Baehr has ways of making you laugh

Laughter is contagious, of that there is no doubt.

See and hear someone in the grip of uncontrollable mirth, and some of it will transfer, even when the original prompt is obscure. Did anyone ever know or care what set off "The Laughing Policeman"?

Intrigued by this phenomenon, and by the mechanical variety of different people's laughs, German performance artist Antonia Baehr has created a one-woman show, Laugh, in which she "performs" laughter scores as if they were musical compositions, or, in some cases, choreography, isolating and analysing all that crumpling, knee-slapping and shoulder-shaking.

Dapper in a three-piece man's suit, Baehr sits at a music stand, her face a sober blank between being creased or distended in the service of the "notes". Each piece takes a distinct form. One draws attention to pitch and mouth-shape, contrasting a cascading feminine laugh with a gravelly chuckle, a hearty, rolling laugh with a closed-lip one (rather sinister, this). Another piece homes in on vowels, examining the effects of "huh" as against "haw", "heh" or the vowel-less eruption (more common than you'd think).

After each piece Baehr stands up and gives a stiff little Teutonic bow. She can't risk smiling, which might impinge on the matter in hand, though during one piece she cleverly has the audience believe she's corpsing, when its all a put-up job. It's very catching.

By coincidence, for one night only, across town Jos Houben, founder member of Complicite, was giving his lecture-demo The Art of Laughter, an equally engaging analysis of some of the tropes of physical comedy, specifically the pratfall. Such a trigger, he explains, knows no national boundaries, nor do we have any choice in the matter. It's our shared humanity, our verticality, that makes us laugh when someone briefly loses it. We don't laugh when, say, a horse falls, since it has no pretensions to uprightness. You might expect a forensic analysis of comedy to kill it dead. But Houben remains funny, even when you know what's coming. QED.

Dance Choice

For size and scope, no dance company beats American Ballet Theatre, at Sadler's Wells for a week. Programme One (Tue, Thur & Fri) has work by Balanchine, plus two UK premieres; Programme Two (Wed, Sat & Sun), classics by Balanchine, Tudor and Paul Taylor. Ballet Boyz: The Talent (above) showcases the nine young inheritors of the Ballet Boyz mantle, in new work. (Tour starts at Richmond Theatre, Tue).