A few times a month, I buy a bag of coffee at the supermarket on my street. I enjoy the ritual of standing before the twenty or thirty whole-bean options in the coffee aisle, imagining how the different roasts and origins might taste. This past Sunday, though, I was surprised to see how my coffee choice influenced the actions of a stranger.

I noticed another shopper in the coffee aisle, engrossed in selecting the perfect coffee for the week. Even after I had paused, nabbed a promising-looking bag, and walked off, she was still weighing her options. I don’t blame her – coffee is very important.

As I got ready to leave the store, I almost laughed when I saw her at the register. After all her cost-benefit analysis back in the aisle, she’d selected the exact same coffee that I had! The odds of us choosing the same coffee at random, considering the aisle of options, was pretty low. Instead, it seemed like my coffee choice might have signaled to her that this specific roast was more delicious and well-liked than the others. I could have influenced her choice without even speaking a word.

Although I thought this was funny at the time, I can’t say that I would’ve done differently if I had been in her place. We call this effect “herding,” and it occurs when we act based on how those around us behave. When searching for a place to eat downtown, you might see a long line out the door of a restaurant and think, “That place must be good if everyone else is standing in line, I better check it out.”

Sometimes restaurants really are just more popular because they’re higher quality, but it’s easy to see how it can become a problem. I’m not the world’s greatest coffee expert, so if I ended up leading herds of people at my local grocery store, the other customers might not be better off.

Of course getting worse coffee isn’t the biggest mistake you can make while shopping. Herding can lead to bigger problems in other cases, though (think the stock market),  and it’s worth looking out for. I don’t have as academic a background as some of the researchers in the lab, but working here has taught me more about these biases, and it’s been fun to notice these mistakes in day-to-day life.

~M.R. Trower~