THE actress and the bishop: the comic trope assumes that the two are opposites. Theatre and religion have always had an uneasy relationship, the morals of the average thespian not always being of a standard regarded as appropriate by the Church. So in the story of Aimee Semple McPherson, the founder of the Foursquare Church and theatrical impressario par excellence, we encounter an alluring combination of actress and prelate, evangelist and showgirl.

To some, Sister Aimee (Radio 4, Monday, repeat) was a Princess Diana figure - raised and then brought low by the media. Certainly, in the 1920s and '30s, McPherson held the kind of fascination for the American public as did Diana. When, after the death of her first husband, she set up the Angelus Temple, McPherson engaged the vast technical resources of Hollywood to stage enactments of Old Testament stories, live illustrations to her sermons.

Add to that a mystery disappearance in 1926, which encouraged in the faithful speculation of a Messianic kind, and Sister Aimee's fame was assured. Yet, as Naomi Grimley's documentary demonstrated, controversy still surrounds McPherson's motives and character; and, not least, what happened during that five-week absence. Was she kidnapped, as she claimed; or had she eloped with her sound engineer?

In all of this, entertaining though it was, we missed any discussion of the character of McPherson's faith and preaching. It was left to a member of the Foursquare Church to remind us that it was her work in the 1930s, during the Depression, that fed hundreds of thousands when central government was withdrawing from aid programmes. Not bad for a Canadian farm-girl.

You can probably imagine the sound of the laughter that accompanied McPherson's fall from grace: the nasal snort, the hacking from the back of the throat. In Word of Mouth: Why do we laugh? (Radio 4, Tuesday of last week), Michael Rosen invited listeners to compare the sounds of spontaneous and forced laughs. Can we tell the difference?

With the help of Professor Sophie Scott, yes, we could. Natural laughter releases the mechanics of our face, so that nasal passages are liable to emit uncontrolled, high-pitched squeals - quite different from the sound of fake laughter.

But, as Professor Scott pointed out, fake or "social" laughter is a vital part of our communication system, something that we do to signal our willingness to co-operate in a dialogue. We use this kind of laughter more than we think we do, and it appears to be a deeply embedded response.

People also laugh to show that they are intent on having a good time. Witness the studio laughter that accompanies radio comedies such as I've Never Seen Star Wars (Radio 4, Tuesdays); last week, it featured Ann Widdecombe in conversation with Marcus Brigstocke.

Miss Widdecombe has now achieved the status of a Tony Benn, drawing audiences despite her politics; and yet, however many "Audiences with. . ." shows she might do, she is no entertainer, nor was she meant to be. The audience laughed determinedly, nevertheless.