For example, young people entering the workforce may score well in job interviews if they exude self-confidence, she said, but that can quickly sour if a new employer doesn't provide them with the perks or promotions they feel they deserve. "They don't set the right goals for themselves, because they are overconfident -- and that's when it blows up in their face," Twenge said.
The blame for all this may lie with well-intentioned adults, she suggested.
"These kids didn't raise themselves, they got these ideas from somewhere," Twenge said. With Mom and Dad handing out endless praise, kids today readily believe they are somehow superior, she said. And teachers aren't blameless, either: According to Twenge, research shows that high school teachers now give out an "A" grade more easily than their counterparts did in the 1970s, even though today's high school students report doing less homework than students from that era.
Not everyone interpreted the new findings in the same way, however. Jennifer Crocker is a professor of psychology at the University of Michigan and a longtime researcher in self-esteem. She said that by selecting data from 1975 and 2006, Twenge and Campbell have only presented two moments in time and have not shown evidence of any decades-long trend.
And based on available academic data, today's young Americans might be right to be more self-confident, Crocker argued.
"The fact is that we are all getting smarter -- IQ is going up quite dramatically over this same period of time," Crocker noted. "Students may believe that they are getting trained better than they used to, that they are learning skills that they didn't use to have. So, maybe their predictions aren't unreasonable."
But Twenge, who is the author of a book on young people's self-views called Generation Me, isn't convinced. In fact, she believes that today's parents may be sending another crop of young Americans down the same path.
"I have a 2-year-old daughter," she said. "I see the parenting of kids around her age, and I haven't seen this changing. Look around -- about a fourth of the clothing available to her says 'Little Princess' on it."
There's more on kids and healthy self-esteem at the Nemours Foundation.
SOURCES: Jean Twenge, Ph.D., associate professor, psychology, San Diego State University; Jennifer Crocker, Ph.D., Claude M. Steele Collegiate Professor of Psychology, University of Michigan, Ann Arbor; November 2008 Psychological Science