Many years ago when I was working with Ian Groves at Inverurie West to illustrate the sermon Ian was giving I dressed up in my oldest most ragged clothes (this was not that hard), did not shave for a few days, donned bonnet and hooded top with dark glasses. Midway through the service I stumbled in through one of the back doors as Ian talked (studiously ignoring me), and lurched down one of the aisles, mumbling to myself. I sat in a pew for a few minutes, before getting up to wander around the church before heading out of one of the doors, still stumbling and muttering.
It proved a perfect illustration for Ian later in the service as no one got up to ask me if I was okay or to offer assistance.
In a variation on this kind of social experiment, the New York City Rescue Mission have carried out their own. The powerful results you can watch above. They say:
In this social experiment, unsuspecting people walked by relatives pretending to be homeless. Would they notice their family members? Or have the homeless become invisible?