Many people hate to walk away from a situation they’ve invested significant time, money or resources on, even if it’s hopeless.
Those wasted efforts are called ‘sunk costs’ and the more you spend, the more you’re likely to keep at it.
It turns out our primate cousins act the same way, according to a new study from Georgia State University.
Researchers taught dozens of monkeys to play a video game and, rather than starting over on a new level, the animals kept trying to win the same one round.
In fact, they spent up to seven times as long as they should have on one round when they would have had a better chance of getting a treat just skipping ahead to the next one.
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Capuchins and macaques had to keep a cursor on a moving target to get a reward. If they spent too long on a level they wouldn’t get a treat, but the monkeys kept trying to win the same one round, rather than just start over on another
That’s because of a combination of uncertainty about the outcome and an ingrained evolutionary mechanism that helps us balance costs and benefits, according to a new study published in Scientific Reports.
Julia Watzek, a researcher in Georgia State University’s Center for Behavioral Neuroscience, worked with her graduate advisor, Sarah Brosnan, on the analysis.
Brosnan, is affiliated with the GSU’s Center for Behavioral Neuroscience and researches how animals perceive cooperation and reciprocity.
She’s worked with the monkeys at the university’s Language Research Center for more than two decades, calling them ‘my second set of kids.’
To test Watzek’s theory, Brosnan had 26 capuchins and seven rhesus macaques play a simple video game.
Sticking to a losing proposition, known as the ‘sunk cost’ phenomenon, is evident in other primates besides humans and has been demonstrated in pigeons and rats, too. Researchers say that suggests there’s an evolutionary mechanism at play, not just pride or embarrassment
The animals needed to use a joystick to move a cursor onto a moving target, then keep it with the target as it kept moving.
If they succeeded, they’d hear a ‘whoop’ sound and get a treat.
But if they failed to keep the cursor on the target, there was no sound and no reward, only a new round of the same game.
Brosnan trained the monkeys on the basics of the game, then tested them on rounds lasting one, three or seven seconds.
‘Monkeys have really quick reaction times on these games,’ she said, ‘so one second to them is actually a long time.’
Here’s where the sunk cost principle comes in: Most rounds were only one second long, so if the monkeys didn’t get the reward after that, it was smarter for then to quit and start a new round
‘That would likely get you a treat sooner than if you had kept going,’ Watzek said.
But, like a human throwing good money after bad, the monkeys kept trying with the same round.
‘They persisted five to seven times longer than was optimal,’ said Brosnan, ‘and the longer they had already tried, the more likely they were to complete the entire task.’
Since there was a chance the game might last longer, Watzek say uncertainty also played part in their behavior.
The sunk-cost effect was more evident in the macaques, but the capuchins struggled to let go, too.
It’s also been demonstrated in pigeons and rats, Science Alert reported.
Since it’s evident across species, Watzek and Brosnan believe there’s an evolutionary component to the phenomenon.
Studying it in animals ‘teaches us something about how their minds work,’ Watzek said, ‘as well as our own.’
It also indicates things like pride or embarrassment—generally human traits—are not the main factors in the sunk cost phenomenon.
Brosnan readily admits that sticking to something you’ve invested a lot of time in isn’t always a bad idea.
‘Sometimes, you need to have patience—that helps when you’re foraging for food, hunting prey, waiting for eggs to hatch, seeking a mate, or building a nest or enclosure.’
But sometimes there’s a good reason to stop trying.
‘When we find ourselves sticking with things, we should also be a little reflective,’ she said.
‘Do I have a good reason to keep trying? Or should I leave with no reward, because it will save me more in the long run? That’s really hard to do. But hopefully we can use our cognitive abilities to help us overcome the emotional heartache of occasional sunk costs.’