Gambling doesn't pay for pigeons
Some gamblers like to forgo their winnings for the chance of a much bigger win - and it seems pigeons like to take the same risk.
Research by Thomas Zentall and Jessica Stagner from the University of Kentucky shows pigeons prefer an all-or-nothing outcome rather than the guarantee of a much smaller reward.
The researchers say this runs contrary to optimal foraging theory, which says animals evolve to make the most rational choices possible to guarantee their survival.
Instead it seems pigeons behave more like human gamblers, risking everything for the small chance of a big return.
In the experiment, which appears today in Proceedings of the Royal Society B, eight pigeons were taught the outcomes of two different sequences if they pecked either a vertical or a horizontal line on a screen.
They learned that if they chose the vertical line, they had a 20 per cent chance of a big food reward (10 pellets) and an 80 per cent chance of no reward at all (0 pellets). If they chose the horizontal line, they had a guaranteed reward of three pellets - effectively a non-gambling option.
When the pigeons were then presented with the choice of pecking either vertical or horizontal lines, to the surprise of the researchers, most chose the vertical line despite the fact that it gave them less food overall.
Averaged over many trials, six of the eight pigeons made choices that gave them an average of two food pellets over an alternative three.
"This choice behaviour mimics human monetary gambling in which the infrequent occurrence of a stimulus signalling the winning event is overemphasised and the more frequent occurrence of a stimulus signalling the losing event is underemphasised," the researchers write.
In other words, we only remember our wins, not our losses.
Commenting on the research, Dr K-lynn Smith who is a behavioural biologist in the School of Biology at Macquarie University says the results are interesting because they contradict accepted theory.
"Animals are supposed to make rational decisions," Smith said.
"An animal would normally think 'what's the easiest way to answer this question?' or 'what's the fastest way to get the food'?- that's why these results are so surprising.
"What we're seeing here is the concept of a jackpot - you have a very positive feeling when you suddenly get a huge amount of food and you remember that very well, whereas when you lose and you didn't get what you want you discount that."
Smith believes the pigeon's behaviour may have something to do with their lifestyle.
"Pigeons spend their time looking for seeds or trees that are blooming. These are patchy food sources where there might be a big win if you hit the right patch," she says.
"So it could be that they are being driven to find the big rewards where there could be a huge amount that will pay off and feed you all at one time, rather than staying on a food source where there is very little [reward].
"It could also be that the pigeons in the experiment weren't that hungry. They knew they were always going to get back to their cage to get food. So it's possible that they didn't need this reward as much - it wasn't a life and death situation."
Either way, Smith says it raises some interesting questions.
"Perhaps it tells us the reward system in pigeons is more similar to humans than we think," she said.