The pitfalls of persistence
Why your brain makes bad decisions sometimes
“I hated the movie but decided to suffer through it because I had paid for the ticket…in 3D!”
“The store was overpriced but I bought the dress because I drove all the way out there.”
“His business isn’t doing well but he’s sticking with it because he’s invested so much time and money in it already!”
Sound familiar? How many times have you persisted at a task that you know deep down is an exercise in futility?
In theory, decisions should be made based on the magnitude of future benefits for the decision-maker. However, in the real world we often make decisions based on the magnitude of past resources that have already been expended and cannot be recovered (time and money). This “sunk costs” phenomenon makes us persist with our original choices even in the face of better alternatives. If it makes you feel any better, we aren’t the only species susceptible to the sunk costs fallacy. Scientists have discovered that bad decision-making is an evolutionary glitch and exists even in animals other than humans.
How to test if animals make bad decisions based on sunk costs?
Scientists at the University of Minnesota used a clever experimental setup to test susceptibility to sunk costs across three species: mice, rats, and humans. For rats and mice, they exploited their natural tendency to forage for food. So they designed a “restaurant” for rodents where the menu consisted of four flavors of food pellets: plain, grape, chocolate, and banana (yum!).
Each flavor was served at a different table that had a decision-making area (offer zone) and a wait-for-the-food area (wait zone). While in the decision-making area, a tone was played that indicated how long the animal would have to wait before it got the food. The wait time varied randomly between 1-30 seconds. Here, they had the choice to either enter the wait area or skip that table and move to the next one. In the wait area, sound tones counted down to indicate how much time was left before the animal would get the food pellet. Here, the animal could choose to wait for the food or to leave at any time and move to the next table. If they left the wait area before the time ran out, they could not return to that particular flavor without going through all the other flavor tables in the restaurant first. Here’s a schematic to explain the experimental setup:
How to quantify bad decision-making influenced by sunk costs in humans?
For Netflix-loving, instant streaming-craving Homo Sapiens, scientists modified the foraging task slightly. Knowing how we can all forego food and sleep while binge-watching our favorite shows online, they modeled a web-surfing task for human participants. To ensure that results could reliably be compared across species, they retained the overall basic premise of the rodent experiments while modifying it to sufficiently motivate our superior human brains.
Subjects could view short videos in one of four galleries under the following categories: dance, accidents, landscapes, or kittens. They were shown how long they would have to wait for the video to download which varied randomly between 1–30 seconds. For each video they could opt to watch the video or skip and move on to the next viewing gallery (similar to the offer zone in the rodent test). Once they clicked on the “stay” option and decided to watch the video, the screen would show a download progression bar indicating how long they would have to wait to view the video (similar to the wait zone in the rodent test). The download could be quit during this wait phase to move on to the next viewing gallery.
So, what’s the verdict?
The researchers found that mice, rats, and humans all fell prey to the sunk cost effect. The more time that rodents spent in the wait area awaiting the food pellet, the more likely they were to persist till the end. Similarly, the longer that humans waited for the video to download, the more likely they were to stay till it finished downloading to watch it.
Weirdly, it turned out that the time rodents and humans took to decide on the offer had no impact on how much they then persisted in waiting for it. Only when they had committed to a particular flavor food pellet or video did their probability of persisting till the very end increase. These experiments show that we keep track of effort invested in waiting, not deciding.
Also, the longer they waited for their chosen reward, the more likely they were to persist till the end. In short, the more resources (time/money/energy) you commit to a particular task, the stronger your resolve to stay the course even if it is to your own detriment! On the other hand, the amount of time spent waiting correlated positively with how much the reward was valued. For example, after consuming the food pellet rodents lingered longer at the table where they spent a longer time waiting and humans rated videos that took longer to download as more enjoyable. Now you know why you cherish an outcome you worked really hard for more than an easy victory.
Why would evolution want you to persist in the face of failure?
Scientists postulate that two distinct decision-making algorithms may be at play in the brain when making choices based on sunk costs. Before committing to a task, the brain has to estimate its value to an organism by predicting future outcomes. This is a complex and difficult process. Therefore, brains of different species may have evolved in a similar manner to use past effort as a measure of predicting future value. Unfortunately, in many real-life scenarios there may only be a very limited correlation between past resources spent and future value to be gained. In such cases the parts of our brain that evolved to minimize wastage of resources kicks in and urges us not to stop till we have achieved our goal. So let’s hope our brains continue to learn and evolve to make better life-choices!
Turning lemons into lemonade
Perhaps evolution has dealt us a raw deal. But there’s a silver lining yet. Understanding the neurological basis of decision-making can have far-reaching implications for developing better educational programs, economic policies, and interventions for psychiatric disorders. For instance, understanding the neurobiology of sunk costs can aid in the treatment of addiction by developing drugs that alter the underlying malfunctioning neuronal circuitry or by use of cognitive behavioral therapy. This is not an unattainable goal given that the one thing we excel at as scientists is persistence!
You can follow this crossword-solving, travel-seeking, camera-touting scientist constantly torn between coffee and chai on Twitter @NeuroRaeesa
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