At DePaul University, the tip-off to one student's copying was the purple shade of several paragraphs he had lifted from the Web; when confronted by a writing tutor his professor had sent him to, he was not defensive — he just wanted to know how to change purple text to black.

And at the University of Maryland, a student reprimanded for copying from Wikipedia in a paper on the Great Depression said he thought its entries — unsigned and collectively written — did not need to be credited since they counted, essentially, as common knowledge.

Professors used to deal with plagiarism by admonishing students to give credit to others and to follow the style guide for citations, and pretty much left it at that.

But these cases — typical ones, according to writing tutors and officials responsible for discipline at the three schools who described the plagiarism — suggest that many students simply do not grasp that using words they did not write is a serious misdeed.

It is a disconnect that is growing in the Internet age as concepts of intellectual property, copyright and originality are under assault in the unbridled exchange of online information, say educators who study plagiarism.

Digital technology makes copying and pasting easy, of course. But that is the least of it. The Internet may also be redefining how students — who came of age with music file-sharing, Wikipedia and Web-linking — understand the concept of authorship and the singularity of any text or image.

“Now we have a whole generation of students who've grown up with information that just seems to be hanging out there in cyberspace and doesn't seem to have an author,” said Teresa Fishman, director of the Center for Academic Integrity at Clemson University. “It's possible to believe this information is just out there for anyone to take.”

Professors who have studied plagiarism do not try to excuse it — many are champions of academic honesty on their campuses — but rather try to understand why it is so widespread.

In surveys from 2006 to 2010 by Donald L. McCabe, a co-founder of the Center for Academic Integrity and a business professor at Rutgers University, about 40 percent of 14,000 undergraduates admitted to copying a few sentences in written assignments.

Perhaps more significant, the number who believed that copying from the Web constitutes “serious cheating” is declining — to 29 percent on average in recent surveys from 34 percent earlier in the decade.

Sarah Brookover, a senior at the Rutgers campus in Camden, N.J., said many of her classmates blithely cut and paste without attribution.

“This generation has always existed in a world where media and intellectual property don't have the same gravity,” said Ms. Brookover, who at 31 is older than most undergraduates. “When you're sitting at your computer, it's the same machine you've downloaded music with, possibly illegally, the same machine you streamed videos for free that showed on HBO last night.”

Ms. Brookover, who works at the campus library, has pondered the differences between researching in the stacks and online. “Because you're not walking into a library, you're not physically holding the article, which takes you closer to ‘this doesn't belong to me,' ” she said. Online, “everything can belong to you really easily.”

A University of Notre Dame anthropologist, Susan D. Blum, disturbed by the high rates of reported plagiarism, set out to understand how students view authorship and the written word, or “texts” in Ms. Blum's academic language.

She conducted her ethnographic research among 234 Notre Dame undergraduates. “Today's students stand at the crossroads of a new way of conceiving texts and the people who create them and who quote them,” she wrote last year in the book “My Word!: Plagiarism and College Culture,” published by Cornell University Press.

Ms. Blum argued that student writing exhibits some of the same qualities of pastiche that drive other creative endeavors today — TV shows that constantly reference other shows or rap music that samples from earlier songs.

In an interview, she said the idea of an author whose singular effort creates an original work is rooted in Enlightenment ideas of the individual. It is buttressed by the Western concept of intellectual property rights as secured by copyright law. But both traditions are being challenged.

“Our notion of authorship and originality was born, it flourished, and it may be waning,” Ms. Blum said.

She contends that undergraduates are less interested in cultivating a unique and authentic identity — as their 1960s counterparts were — than in trying on many different personas, which the Web enables with social networking.

“If you are not so worried about presenting yourself as absolutely unique, then it's O.K. if you say other people's words, it's O.K. if you say things you don't believe, it's O.K. if you write papers you couldn't care less about because they accomplish the task, which is turning something in and getting a grade,” Ms. Blum said, voicing student attitudes. “And it's O.K. if you put words out there without getting any credit.”

The notion that there might be a new model young person, who freely borrows from the vortex of information to mash up a new creative work, fueled a brief brouhaha earlier this year with Helene Hegemann, a German teenager whose best-selling novel about Berlin club life turned out to include passages lifted from others.

Instead of offering an abject apology, Ms. Hegemann insisted, “There's no such thing as originality anyway, just authenticity.” A few critics rose to her defense, and the book remained a finalist for a fiction prize (but did not win).

That theory does not wash with Sarah Wilensky, a senior at Indiana University, who said that relaxing plagiarism standards “does not foster creativity, it fosters laziness.”

“You're not coming up with new ideas if you're grabbing and mixing and matching,” said Ms. Wilensky, who took aim at Ms. Hegemann in a column in her student newspaper headlined “Generation Plagiarism.”

“It may be increasingly accepted, but there are still plenty of creative people — authors and artists and scholars — who are doing original work,” Ms. Wilensky said in an interview. “It's kind of an insult that that ideal is gone, and now we're left only to make collages of the work of previous generations.”

In the view of Ms. Wilensky, whose writing skills earned her the role of informal editor of other students' papers in her freshman dorm, plagiarism has nothing to do with trendy academic theories.

The main reason it occurs, she said, is because students leave high school unprepared for the intellectual rigors of college writing.

“If you're taught how to closely read sources and synthesize them into your own original argument in middle and high school, you're not going to be tempted to plagiarize in college, and you certainly won't do so unknowingly,” she said.

At the University of California, Davis, of the 196 plagiarism cases referred to the disciplinary office last year, a majority did not involve students ignorant of the need to credit the writing of others.

Many times, said Donald J. Dudley, who oversees the discipline office on the campus of 32,000, it was students who intentionally copied — knowing it was wrong — who were “unwilling to engage the writing process.”

“Writing is difficult, and doing it well takes time and practice,” he said.

And then there was a case that had nothing to do with a younger generation's evolving view of authorship. A student accused of plagiarism came to Mr. Dudley's office with her parents, and the father admitted that he was the one responsible for the plagiarism. The wife assured Mr. Dudley that it would not happen again.