cropped model

I have been looking at shots of models in magazines and quite often come a cross photos where the subject has been cropped cutting off the top of the head and or feet. The photos seem to work.
My question is can any one explain to me this technique, is there a rule to be applied.

The principle behingd it is the Gestalt theory of 'closure' - in a nutshell this says that it 'invites viewer participation in identifying and completing the form' and creates pathways for the eye to enter and exit the picture.

The result is supposed to be a more dynamic composition that aids the viewer's eye in exploring the image.

A decent explanation can be found at Apogee Magazine

Cheers,
Pete

Good article Daytripper. Thanks.

Get it wrong though and it just looks as though you cropped bits off at random. It still needs balance.

thanks

Excellent, I look at lot of photos within the media and pick up things with out really understanding everything. I am grateful for the explanation and the apogee article.