The study - "U.S. males and pornography, 1973-2010: consumption, predictors, correlates." is from 2011. It's not new.

The GSS survey only asks the question - Have you watch an x rated film this year. Several problems:

1) X rated films in the 70's could have been A Clockwork Orange. Hardly comparable to online fare of 2014.

2) Does anyone watch an x rated film anymore. Technically guys are watching short clips, not films, and there are no ratings. Could this alter answers?

3) Watching a single film in one year is equivalent to watching 5 hours of porn per day, every day. Such a simple question cannot assess how porn use has changed.

4) GSS survey is for those over 18. It's clear that under 18 viewing of porn films has dramatically increased since 1975.