If you’ve shopped on sites like Amazon or eBay in recent memory, you’ve likely noticed the appearance of Twitter or Facebook icons on the webpage encouraging you to share the product info with your online social networks. Given the presence of those icons on the product page, though, have you ever found yourself second-guessing the privacy of your purchase as a wave of unchecked paranoia swept over you because maybe, just maybe you had accidentally linked to your Facebook or Twitter account and news of your purchase would soon be broadcast to your friends and colleagues?

If this sounds familiar, guess what: turns out you’re not alone for feeling that way. A new study by way of the University of Miami School of Business Administration has found that the presence of Facebook and Twitter logos on a shopping website increases the likelihood that consumers will buy some products and reduces the likelihood that they will buy others.

The study found that consumers who saw a social media icon near a product that might embarrass them were significantly less likely to buy that product than those who saw the same product without the icon. On the other hand, consumers who viewed products they would be proud to show off were significantly more likely to buy than those who saw the same product with no such icon.

“Our study finds that the mere presence of social media icons on a web page where we shop appears to cause us to feel as if our purchases are being watched by our social network, and we adjust our buying decisions accordingly,” said Claudia Townsend, an assistant professor of marketing at the University of Miami School of Business Administration who conducted the research with Empirica’s David Neal. “Marketers should be aware that the placement of these symbols in their web design strategy could have a major impact on buying behavior.”

The study enlisted 200 participants to explore a variety of products, some that people were happy to display in public (e.g., women’s sportswear or colognes) and some that people did not want to share with the public (e.g., compression underwear or acne medication). When the product was one for which public consumption is desirable, like the cologne, the presence of the Facebook and Twitter icons made people 25% more likely to purchase. But when the product was more private in nature, like a product for acne treatment, the icons suppressed purchase intentions, also by 25%.

What’s so startling about this study is that people seemingly didn’t even realize they were adjusting their shopping habits because of presence of the Twitter and Facebook logos. The impact on intended buying behavior emerged regardless of whether people had any memory of having seen the social media icons, meaning the logos were seeping into the subconscious of these shoppers and then creating turmoil with their senses of pride and shame.

Businesses will see a study like this as a powerful advertising tool. More than marketing strategies, though, this study offers a penetrating glimpse into how the presence of social media in our lives has influenced our inhibitions even when we’re alone. The presence of something as seemingly unobtrusive as a Twitter or Facebook logo serves as an constant reminder that our social networks are always nearby and, with that distance between Us and Them becoming shorter, the membrane that seals off our privacy seems to have become all the more permeable.

In other words, the chance that we ever feel genuinely alone, even when we are physically alone, appears to be dwindling.

As a result, icons representing Twitter and Facebook on shopping websites have become unintended mechanisms that can cause us to police our shopping habits. They inspire in us the unfounded speculation that we are being watched by omnipresent internet overlords who will then betray our privacy and broadcast details of our shopping habits to our online social networks. Worse, it causes our imagination to turn against us as we worry about what our friends would say if they could only see what we were buying online. Reaching back to the simple psychological principles of punishment and reward, the impact of possibly sharing our purchase on our social networks could produce in us a sense of shame or a groundswell of pride.

This study highlights a fascinating example of how our involvement with social media sites can unknowingly police our lifestyle choices even as we consider something as innocuous as the purchase of Neutrogena acne treatment or Ralph Lauren Polo. One of the hallmarks about shopping online is that it has always been a way for people to purchase whatever they want without running the risk of public embarrassment for what they buy. Those days, however, seem to be waning if the results of this study are to be believed.

If the mere reminder that we’re constantly available to our friends and colleagues through Facebook and Twitter is enough to influence something as minor as these types of purchases, in what major ways are these diminutive icons affecting our behavior?