Are College Students Studying Less?

I've seen a lot of hand-wringing about this study:

New research, conducted by two California economics professors, shows that over the past five decades, the number of hours that the average college student studies each week has been steadily dropping. According to time-use surveys analyzed by professors Philip Babcock, at the University of California Santa Barbara, and Mindy Marks, at the University of California Riverside, the average student at a four-year college in 1961 studied about 24 hours a week. Today's average student hits the books for just 14 hours.

The decline, Babcock and Marks found, infects students of all demographics. No matter the student's major, gender, or race, no matter the size of the school or the quality of the SAT scores of the people enrolled there, the results are the same: Students of all ability levels are studying less.

It seems to me that "studying" has gotten a lot more efficient over the years. Circa 1964, a research paper meant countless hours in the stacks at the library, a typewriter, and a bottle of liquid paper. Or something. I actually have no idea how it worked exactly. Only that the personal computer and the Internets made everything a lot more efficient.