Whenever severe winter weather approaches, grocery store aisles are always clear of eggs, bread and milk.

But why is that the case?

The CDC recommends bread as a no-cook food to stock ahead of a storm, but not perishables like milk and eggs. A power outage means those foods may not last until the storm passes.

The Atlantic reported that buying perishables may be a matter of psychology.

Duke University behavioral economist Dan Ariely said it's a matter of seeing others doing something and feeling the need to join in. "If we go somewhere and we see other people buying those particular things, all of a sudden (we're) even more interested in those (things)," he said.

"It's like saying, 'The storm will be over soon and I won't be stuck in this situation for long,'" clinical psychologist Judy Rosenburg told HowStuffWorks.

So it may be fine to get bread, milk and eggs as long as you have enough non-perishable foods as well.

Cox Media Group