Pop-ups can be annoying but tend to be ignored
Internet users are unable to distinguish between genuine pop-up warnings messages and false ones, a study at North Carolina State University has found.
The study examined the responses of undergraduates to messages which popped up while they did other tasks on a PC.
Seeing the pop-ups as a mere annoyance the majority clicked 'OK'.
Fake pop-ups are a well-known vehicle for cyber-criminals to install harmful software on PCs.
"This study demonstrates how easy it is to fool people on the web," said co-author Michael Wogalter, professor of psychology at North Carolina State University.
"Be suspicious when things pop up. Don't click OK - close the box instead," said Dr Wogalter."
It is easy to block pop-ups
Participants were fooled by the fake messages 63% of the time, even when warned that some of what they would be seeing would be false.
It suggests that the wording on genuine messages needs to be rethought, said Dr Wogalter.
"I don't know if you could develop a legitimate message that could not be duplicated and used illegitimately," he said.
Tony Neate, managing director of the UK's Get Safe Online campaign advised users to install a pop-up blocker.
"Browsers and most anti-virus software offers them. Pop-ups are either downloading something malicious or trying to sell me something so I just don't want them there at all," he said.