Despite these rigours, the participants have pledged that it would be wholly inappropriate for any of them to chicken out. The whole point of the exercise is to settle a dispute over whether humans can spend a week enduring the same conditions as battery hens.
Of course, it is not an ordeal any of those involved would undertake for chicken feed - they each stand to gain pounds 2,500 if they stay the course.
The four accepted a challenge from the vegan author Rebecca Hall, who wants to expose 'animal concentration camps' used to produce cheap food by intensive farming. To qualify for the cash they will need to share a sloping ground space a metre square and nearly 2 metres high (about 3ft square by 6ft).
The cage has no sanitation and is raised off a stable floor at Ms Hall's home in Woolhope, near Hereford. The four have agreed not to use drugs or sanitation bags.
All barefoot, they will have to survive on the diet of boiled brown rice and beans which will be fed to them down a pipe on to a metal tray outside the cage. They can reach water dripping from a tap. A rope will ring an alarm if they want to be set free.
Those in the cage include Daryl Heathfield, 27, from Newent, Gloucester. His left leg has been amputated and he wants the money to buy a more comfortable replacement.
He is joined by a 15-stone builder, Bill Davies, 34, of Leominster, and Stuart Wastie, 21, a photography student, and Richard Brett, both from Witney, near Oxford .
Mr Brett, 34, a 6ft 3in lorry driver, said: 'I'm stuck in a lorry cab all day and I thought the money would be useful. It's going to be disgusting but we will have to co-operate to retain a certain amount of dignity.'