Rats! Just when we thought only humans were this silly

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Rats! Just when we thought only humans were this silly

We are not the only species who fall for the sunk cost fallacy - sticking with something when you really do know better

Journalist

In for a penny, in for a pound. That cliché sums up the flawed thinking of the “sunk cost” fallacy: sticking with a bad choice or risk even when there’s a better option.
It’s a human instinct. Waiting in a line that’s not moving at the shop. Throwing money and effort into a project that’s not working, instead of dropping it. Staying in a broken relationship because it’s lasted 10 years, so why walk away now?
A new study shows that people are not alone in making this mistake. Rats and mice do it too.
“This well-known cognitive phenomenon has long been considered a problem unique to humans,” says lead scientist Professor Brian Sweis, from the University of Minnesota’s medical school. “Our research has discovered that humans are not the only species that share these economically irrational flaws.”To test this, a collaborative experiment was set up for rats, mice and students, and the results published in the journal Science.
“The key to this research was that all three species learnt to play the same economic game,” says Sweis from the neuroscience department.
“Mice and rats spent time from a limited budget foraging for flavoured food pieces while humans similarly spent a limited time budget foraging for what humans these days seek – entertaining videos on the web.”
What they found was that “all three species become more reluctant to quit the longer they waited, demonstrating the sunk cost fallacy”.
All the subjects hesitated before accepting or rejecting choices (for food or videos) during the initial decision before the countdown. “It’s as if they knew they didn’t want to get in line until they were sure,” says Sweis.“These tasks reveal complex decision processes underlying the conflict between really wanting something on the one hand versus knowing better on the other.”
Neural circuits influence decision making and prior research has demonstrated that “mice and rats use similar neural systems to humans”.
“Mice and rats show regret after making mistakes, and mice can even learn to avoid those mistakes by deliberating first,” said Professor Mark Thomas, another senior author from the neuroscience department.Besides crossing species, the sunk cost fallacy crosses people’s cultures, according to a study by the American Psychological Association.
In a blog on the sunk cost fallacy and how to avoid this “trap”, Indonesian writer Theodora S Abigail said two main psychological factors drive it: the potential of future gain (prospect theory), which justifies increasing risk, and the self-justification theory, which speaks for itself.
“People don’t like to admit they are wrong or made a mistake,” she writes, pointing out that fear plays a role in this.
“At the heart of this fallacy is a fear of ‘waste’. Our time and money are valuable, and it can be hard to turn away after we’ve invested so much in a project,” writes Abigail, noting governments fall into the trap too.“Governments sometimes spend money on new military technology, but they aren’t always successful. Sometimes projects become obsolete.” Sound familiar?
The sunk cost fallacy is dangerous, Abigail warns, because we risk losing more money and time (which can’t be recovered) by sticking with a wrong decision, in effect wasting resources that could have been better spent elsewhere.
Tis human, and apparently also rodent, to err but robots are exempt from this. Adopting rational decision-making patterns may help keep humans one step ahead.​

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