## 4 Results
### Web Familiarity, Fact Checking and Young Users  
One common way to assess the veracity of a piece of news is online fact-checking, i.e., searching for external sources to confirm or disprove the news. In Room 3, the users could see the sources of the articles, and a link to the original article was displayed: we observed that 26.5% of the users clicked at least once on such a link during the test. However, fact-checking activity requires the user to check news against external sources; retrieving the original web article could only confirm its existence and give some clue about the publisher (for instance, by reading other news from the same news outlet, or by technological and stylistic features of the website [46]). True fact-checking would have required the user temporarily leaving the test to browse in search of confirmation on other websites [47]. As anticipated in Section 3, we captured information about the users that left the test for a while, coming back to it a few seconds later, by monitoring when the test tab in the users' browser was no longer the active one. It is worth recalling that we had no way to see what the users were searching in other tabs, if they were actively fact-checking the test articles  
Figure 9: Average accuracy (**a**) and median answering times (**b**) of users for questions in order of presentation to the users. Values in Room 2 are compared to their corresponding values in all the rooms taken altogether. (**a**) Accuracy in Room 2 does not drop progressively. However, it is constantly lower than overall accuracy. (**b**) Users in Room 2 start reading the full text on the first questions, but they get quickly annoyed, and the reading time falls shortly. During the second half of the test, Room 2 users answer even more rapidly than in the other rooms. or just taking a break from the test. Additionally, in our guidelines, we did not explicitly mention the possibility of searching for the answers online. However, estimating how many users fact-check online news is outside of the scope of this work, and it is a research problem that must be addressed properly. We only acknowledge that opening a new tab and coming back to the test later could be a hint of an external research; that we did nor encouraged nor discouraged such activity; and that in the end 18.25% of the users did open another tab at least once during the test. Users who opened a tab answered correctly 78.23% of the time against the 73.82% of the others that did not. Figure 10 reports the average distribution of users' scores, only for those who have opened a tab at least once. The mean of the distribution (15.19 correct guesses over 20) is close to the one in Room 4, significantly higher than in Room 1. Opening a tab to search for an answer online is an activity that we therefore correlate with possible fact-checking due to the positive effects it has on users' tests. Additionally, it is an activity that correlates with the age of the respondents. Figure 11 shows the percentage of users that opened another tab in the browser by age. Each age category is represented by the corresponding lollipop, which is long proportionally to the tab opening rate, and sized after the number of respondents in such an age category. The vertical dashed red bar points out the percentage of users who opened a tab, regardless of their age. Young adults and adults in the age ranges of 20-30 through 50-60 are the most represented in the data, but their tab opening rate is different. Users in the age groups 20-30 and 30-40 showed a higher propensity to open another browser's tab, while users in the 50-60 age group did it significantly less than average. Other categories are under-represented, but they still confirm the general trend: overall, the chances for users to open a new tab while responding to the test are higher for teenagers and young adults, and they decrease substantially with age.