The Internet brings the world to our fingertips, but it turns out that getting information online also has a startling effect on our brains: We feel a lot smarter than we really are, according to a Yale-led study published March 30 in the Journal of Experimental Psychology.

In nine different experiments with more than 1,000 participants, Yale psychologists found that if subjects received information through Internet searches, they rated their knowledge base as much greater than those who obtained the information through other methods.

“This was a very robust effect, replicated time and time again,” said Matthew Fisher, a fourth-year Ph.D. student and the lead author of the study. “People who search for information tend to conflate accessible knowledge with their own personal knowledge.”

For instance, in one experiment people searched online for a website that answers the question, “How does a zipper work?” The control group received the same answer that they would have found online, but without searching for it themselves. When later asked how well they understood completely unrelated domains of knowledge, those who searched the Internet rated their knowledge substantially greater than those who were only provided text. Prior to the experiment, no such difference existed.

The effect was so strong that even when a full answer to a question was not provided to Internet searchers, they still had an inflated sense of their own knowledge.

“The cognitive effects of ‘being in search mode’ on the Internet may be so powerful that people still feel smarter even when their online searches reveal nothing,” said Frank Keil, the Charles C. and Dorathea S. Dilley Professor of Psychology and Linguistics and senior author of the paper.

Keil recalls being cut off from Internet access during a hurricane, and says, “I felt myself becoming stupider by the hour.” For the younger generation, the effect may be even more pronounced. “The cell phone is almost like the appendage of their brain,” he said. “They don’t even realize it’s not real until they become unplugged.”