Shoppers exit a Costco warehouse with carts full of goods Saturday, March 14, 2020, in Santa Clarita, Calif. Efforts to stop the spread of the coronavirus in California are affecting virtually every facet of life in the Golden State in ways big and small and in some cases, surreal. Popular restaurants were desperate for patrons, and typically crowded gyms had plenty of floor space. Some stores limited sales of toilet paper and other goods to combat hoarding. The vast majority of people recover from the new coronavirus. According to the World Health Organization, most people recover in about two to six weeks, depending on the severity of the illness. (Marcio Jose Sanchez) Credit: Marcio Jose Sanchez | AP

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SAN DIEGO — Selfish. Stupid. They’ve been called all sorts of things, the people who are descending on stores in a coronavirus-fueled panic to empty the shelves of pasta, beans, rice, meat, chicken, toilet paper, soap and other items. Greedy. Heartless.

Psychologists and behavioral scientists have another word for them: Human.

“When people feel uncertain, they tend to focus on things that bring them certainty,” said Uma Karmarkar, a neuroeconomist at the University of California, San Diego. “Most of us don’t have the ability to make new vaccines or enact new policies, but the one action that we can control, that feels like we are doing something, is to stock up on supplies.”

This is not new. Panic-buying happened during earlier pandemics. It happened after 9/11. It happens in advance of hurricanes along the Atlantic coast.

“It’s a natural response to a stressful experience,” said Lisa Kath, an associate professor of psychology at San Diego State University.

But the coronavirus is new. Its mechanisms and lethality are not fully understood. With hurricanes, people know what they’re in for, and for how long. They’ve been through them before. And survived.

“With this, we don’t yet know the boundaries,” Kath said. “We have no frame of reference. That just amplifies the fear.”

Amplified fear makes people go into a store and buy 12 rolls of paper towels instead of two. Four boxes of rotini instead of one. Three bottles of hand soap when there are already five at home.

It leads to scenes like this one at the Ralph’s in San Diego’s Mission Valley section on a recent morning, shortly after the store opened. An employee wheeled out a cart with a box of packaged chicken on it. He opened the box to put the chicken in a display case.

A shopper reached around him, into the box, and grabbed packages to drop into her basket.

One, two, three, four … .

“We don’t have room in the freezer for all that,” a man who was shopping with her said.

“We’ll make room,” she snapped.

The panic-buying took off after the World Health Organization declared the coronavirus outbreak a pandemic on March 11. Additional spikes have followed other pronouncements by government officials, including the order Thursday night by Gov. Gavin Newsom telling Californians to stay at home except for “necessary activities.”

Grocery shopping is OK under the order, and Friday morning people started lining up outside a Vons in San Diego’s Clairemont section before it opened. Like other markets, it has put in place restrictions aimed at hoarding, such as limiting how much toilet paper, chicken, meat, eggs and other items people can buy. Within a couple of hours, much of that was gone anyway.

“Struck out again,” a man looking for rice said to his companion.

Store managers and food industry analysts keep stressing that there is no shortage in the supply chain of the coveted items, but the surge in demand is outstripping their ability to keep things on the shelves for long. If people would just buy what they need, officials said, there would be enough for everyone.

That message apparently isn’t getting through for several reasons, the behavioral experts said.

For one thing, we have been told to get ready for at least two weeks of self-quarantine, just in case. Some hoarding is required. But many people, including Californians who have been advised for decades to prepare similarly for earthquakes and wildfires, don’t know how much to buy. In the middle of an unfamiliar crisis, that can lead to overstocking.

So, too, does a desire to get in and out of the store quickly to avoid getting infected. Just grab it and go.

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And when people see others filling their carts to the brim, they do it, too. Humans are social beings who measure the danger of different situations by the reactions of people around them. A herd instinct kicks in.

Then there are all the images on the internet of empty shelves, which scream one word: Scarcity.

“The idea of scarcity is an incredibly powerful one, especially in Western cultures,” said Karmarkar, whose research looks at how consumers make decisions. “Think about all the times you’ve been shopping on the internet and ‘Only One Left’ pops up. We’re conditioned to want it now. There are a lot of messages pushing us in that direction.”

Friday there was a new message pushing in the other direction. Printed on front-door signs and the backs of sales receipts at Sprouts in Clairemont was this: “In these unprecedented times, ALL SALES ARE FINAL. Please keep this in mind when shopping for your weekly needs.” Other stores are issuing similar warnings.

In other words, good luck returning all those Lysol wipes.

Kath, the San Diego State University psychologist, said she thinks it’s important for people as they head out to shop to recognize and label the dominant emotion many are feeling: fear.

“The coronavirus is so far beyond our experience, we don’t feel any sense of control,” she said. “The fear is large, so the behavior is larger.”

She said it would help if shoppers are more self-aware. “Recognize that what you are doing in response to the stress is a natural behavior, but take a deep breath and ask yourself, ‘How much of this do I really need?’ Move from an automatic response to a thoughtful or reasoned response.”

Thursday afternoon, at the Costco in Mission Valley, Jose Lopez, a 34-year-old restaurant worker, said he was trying to do just that.

His cart was half-full with eggs, water, paper towels and other items that he said represented what he would normally buy on a trip to the warehouse, “maybe a little less.” He’s been shopping there for six years.

In response to panic-buying, Costco has put item-number limitations in place and is metering the crowds to control how many people are inside at a time. Lopez said he waited outside for about 15 minutes before it was his turn.

He had been shopping at night, but not any more. There’s no line at night, he said, “but there’s none of the things you want, either.”

Once inside, the Spring Valley resident said he resisted the urge to hoard, despite what he saw going on around him. “We all have to do our part,” he said. “It’s still pretty crazy in there.”

Everyone doing his or her part — that’s played a key role in containing earlier viral outbreaks, according to the book “The Psychology of Pandemics,” by Steven Taylor, a clinical psychologist and professor at the University of British Columbia.

The book, which came out in December, eerily predicts a lot of what’s happening with the coronavirus, although it didn’t foresee toilet paper becoming part of the panic-buying.

Taylor is an expert in anxiety disorders, especially those surrounding health. He got to wondering what would happen to his patients if a pandemic broke out and spent two years researching the project.

“The more I read about pandemics, the more I realized that pandemics were essentially psychological phenomena,” Taylor wrote in a recent article for the Independent. “Pandemics were not simply about some virus infecting people. Pandemics were caused and contained by the way that people behaved.

“Pandemics are controlled only when people agree to do particular things, like covering their coughs, washing their hands, complying with social distancing, and getting vaccinated, if a vaccine is available. If, for various psychological reasons, people refuse to do these things, then the pandemic will continue to spread.”

Watch: What you need to know about handwashing during coronavirus

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