If you’ve ever lived with roommates, chances are you shared a “transactive” memory system with them. One person might have remembered to pay the bills, while another knew the contact details of the plumber. It's common to find social systems that share the information needed by a group across all the members of that group. Systems like these make life easier for individuals, who need only keep track of who knows which nugget.

Transactive memory systems are a common feature of human social groups, but they can be technological, too—and in the case of the Internet, the relationship can be a pretty powerful one. There are already indications that we treat the Internet like a transactive memory partner, remembering only where to find information, rather than the content itself. But could we also be blurring the boundary between our own internal knowledge and the easily accessed knowledge available via search engines? A group of researchers at Yale University think that we are.

Their research, published this week in the Journal of Experimental Psychology, found that after using a search engine, people were more confident in their ability to explain an unrelated topic. To explore the effect, they conducted nine separate experiments, each using between 131 and 280 participants from Amazon’s Mechanical Turk.

In the first set of experiments, participants were presented with a series of questions requiring explanations (such as “why are there time zones?”). In the “induction” phase, the test group was asked to search the Internet for answers and then rate how well they felt they were able to explain the answers. The control group was presented with the same questions, but asked not to use the Internet before rating their explanations. Unsurprisingly, the Internet group was more confident in their abilities to explain the answers.

Then, in the “self-assessment” phase, new questions were presented, and this time both groups were instructed not to search before rating their explanations. This time, even though neither group had actually searched for answers, the Internet group still rated their explanations significantly more highly than the control group.

To control for more factors, the researchers used a new group of participants, adding in a pre-assessment test to check whether the groups rated their explanatory abilities differently right from the beginning. They didn’t—the difference only emerged after using search engines. The effect remained even after the Internet group was told to find the explanation on a particular site, and the control group was presented with the explanation from that same site. This suggests that it’s the act of using the search engine that produces the effect.

The obvious flaw in these experiments is that after being told to search for answers to the first set of questions, the Internet group might have thought that the self-assessment exercise meant “how well could you answer these questions, after searching for the answers?” A second set of experiments clarified this, asking participants to assess their ability to explain based on their current knowledge, with no outside sources. The effect remained.

There were other potential explanations that the researchers wanted to eliminate. What if searching somehow boosted overall cognitive confidence, rather than confidence only about abilities related to information that could be found on the Internet? If this were the case, the effect would be found in explanations for all kinds of questions, not just those that could be found by search engine. A new experiment used autobiographical questions in the self-assessment phase (tough ones, like “What is the relationship between the classes you chose during freshman year of high school and your current career?”). This time, the Internet group didn’t rate their abilities any more highly than the control group. The results suggest that “accessing the Internet does not lead to a general overconfidence, but rather to a more specific illusion of knowledge that occurs only in domains where the Internet would be of use,” the authors write.

Finally, they tested whether the effect still held even if the searches yielded no useful information, by limiting the search timeframes. Even if the search provided absolutely no results, the Internet group rated themselves higher during self-assessment than the control group. This suggests that it really is the act of searching creating the result, according to the researchers. They argue that people are conflating information that’s easily accessible by search with knowledge they already have.

One factor to consider in the results is that the experiments relied on the participants honestly reporting whether or not they had obeyed the instructions to use or not use search engines. Those who reported disobeying were excluded from the analyses. Given that the tasks were completed online, it is possible that dishonesty could have been a problem. However, it’s not clear how the significant result would have been consistently replicated if many participants had lied about this.

The authors indicate concern about the findings, suggesting that they indicate a “systematic failure to recognize the extent to which we rely on outsourced knowledge.” But they also acknowledge that this effect is by no means limited to the Internet. People in certain social environments, or information-rich environments like libraries, may have the same experience, although the vastness and accessibility of the Internet has probably broadened the scope of the effect.

Journal of Experimental Psychology, 2015. DOI: 10.1037/xge0000070 (About DOIs).