Oct 11, 2013 8:30 AM PDT    Text size: 

WASHINGTON, D.C. —  Nearly 25 percent of American men who watch videos online, watch porn, according to a new Pew Internet & American Life survey.

And the percentage of adults who watch or download videos online has grown from 69 to 78 percent since 2009.

Pew tracked Internet users 18 years of age and older in its just released “Online Video 2013" study.

Although the research found that only 12 percent of the total respondents said they watched “adult” videos, the study suggests that the low number “may reflect a reluctance to report the behavior among some adults."

"If the methodology is survey-based, I suspect no-one is likely to admit to watching adult films — other (non-survey-based) viewing data suggests otherwise," Richard Broughton, head of broadband media at research firm IHS Screen Digest, told CNBC.

Only 8 percent of women surveyed admitted to watching online porn.

Supporting the rise in online viewership, particularly the strong appeal for men, Montreal-based PaintBottle in May released an infographic suggesting that porn makes up nearly 30 percent of all the data transferred across the Internet, and that men make up nearly 70 percent of the viewers.

The in-house research also revealed that men hit porn sites 7.5 porn sites per month and spend an average time of about 12 minutes at each destination.