“There is an assumption that free-range chickens are happy chickens. Even if they are producing fewer eggs, at least they are happy. That would probably be the general consumer’s perspective,” says Geoff Hinch, a professor of animal science at the University of New England, who has been preoccupied with poultry welfare these past 10 years.

With a couple of hundred Isa Brown hens, some astroturf, plywood, chicken wire and a few very patient researchers, the work doesn’t rate in the glamour and prestige stakes.

But free-range eggs are rapidly gaining on the caged competition in market share (nearly 30 per cent compared with nearly 60 per cent), and consumers increasingly want to know the chook that laid their egg was living a good life.

The researchers rigged up an experiment where chickens were taught to associate particular colours with good or bad outcomes, that is, worms or no worms. 

A box with a black card above it has worms in it; one with a white card does not. It takes chickens about two weeks to learn the difference. 

When the black and white cards are replaced with neutral (grey) ones, an optimistic chicken will head for the box which was previously black.

“The findings so far are that chickens are generally very optimistic animals”, Professor Hinch said.

The next step of the research is to figure out why, when given the choice, some free-range chickens won’t go outside.