Returning Your Shopping Cart Became A Personality Test Online. The Research Says Something Much Smaller.
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The "shopping cart theory," the claim that whether someone returns a shopping cart to its corral reveals whether they are a good or bad member of society, originated in an anonymous post on the 4chan message board's /pol/ section on May 8, 2020, according to Know Your Meme's documented history of the post, not in any peer-reviewed study. The post argued that returning a cart is "the ultimate litmus test for whether a person is capable of self-governing" and that doing so is "objectively right." It spread widely after a Twitter user reposted it later that year, and it has resurfaced repeatedly since, most recently in 2024 when a viral TikTok video of a mother explaining why she doesn't return her cart drew more than 11 million views, according to USA Today's coverage of the incident.
Actual behavioral research on comparably small, unrewarded, unpunished acts reaches a narrower and less flattering conclusion for the theory: a single observed behavior is a weak predictor of anyone's broader character, and the behavior itself is shaped less by fixed moral character than by what a person sees other people doing at that moment.
A Single Behavior Predicts Far Less Than People Assume
Psychologist Walter Mischel's 1968 book Personality and Assessment reviewed decades of studies testing whether a personality trait, such as conscientiousness, reliably predicted a specific behavior in a specific situation. The correlation rarely exceeded 0.30, a finding researchers still call the "personality coefficient." A correlation of that size means the trait accounts for roughly 9 percent of the variation in the behavior, leaving the other 91 percent to situational factors that have nothing to do with who a person fundamentally is. Later work by researchers Funder and Colvin, published in 1991, found consistency correlations for single behaviors observed across different situations typically ranging from 0.20 to 0.37, rising only when many behaviors are aggregated together rather than judged from one incident. Treating one act, cart return included, as a verdict on someone's character runs directly against this body of findings.
What Actually Predicts Whether Someone Returns A Cart
The closest matching real research comes from studies of littering, a comparably low-stakes, unenforced act of public consideration. In a series of field experiments published in the Journal of Personality and Social Psychology in 1990, psychologist Robert Cialdini and colleagues Raymond Reno and Carl Kallgren tracked whether people littered in a parking garage under different conditions. The strongest predictor wasn't any fixed trait of the people being observed; it was what the environment signaled about what other people typically did there. When the garage already had litter scattered around, and especially when subjects saw another person litter into that already-littered space, littering increased sharply. When the garage was visibly clean, the same behavior by another person had the opposite effect, making littering less likely. Cialdini's team called this the difference between descriptive norms, what people see others actually doing, and injunctive norms, what people believe is approved of; behavior tracked the descriptive norm far more reliably than any stable personal quality.
Anthropologist Krystal D'Costa's 2017 Scientific American article, written three years before the meme existed and later cited retroactively by outlets covering the theory's virality, listed several situational reasons people leave carts unreturned that have nothing to do with self-governance: the distance to the corral, bad weather, young children who can't be left unattended in a vehicle, physical disability, and the assumption that a store employee's job includes collecting stray carts.
What This Means When You See Someone Leave A Cart
None of this means cart return is meaningless, or that norms don't matter; Cialdini's findings actually reinforce that visible cart corrals and visibly returned carts likely do increase how often other shoppers return theirs, the same descriptive-norm effect his team documented with litter. What the research doesn't support is the meme's central claim: that a single instance of a person walking away from a cart reveals a fixed, generalizable truth about their moral character, deducible with more confidence than a psychologist or a priest could offer. The theory's popularity says something real about internet culture's appetite for tidy moral verdicts. It says considerably less about the people making the walk to the corral, or choosing not to, on any given day.
