American teenagers feel more entitled than ever, according to a new study of high school seniors from three different generations.

Teens still crave being rich, but say they are less willing to work hard to earn material belongings, a development that the study's lead author, Jean Twenge of San Diego State University, attributes to increased advertising.

"Common sense would tell you that if you want a lot of material things, you'd be inclined to work harder," Twenge says. "But advertising portrays these shiny things but not the dirty work that goes into getting them."

The study asked more than 350,000 high school seniors between the years of 1976 and 1978, 1988 and 1990 and 2005 and 2007 about the importance of money, work and of owning certain material things.

According to the study, published Tuesday in the Personality and Social Psychology Bulletin, 62 percent of students surveyed between 2005 and 2007 think it's important to have a lot of money, compared to just 48 percent between 1976 and 1978; meanwhile, 39 percent of students surveyed between 2005 and 2007 said they didn't want to work hard, compared to just 25 percent in the 1970s.

Though the so-called "fantasy gap" between wanting a lot of money and not wanting to work hard has increased since the 1970s, American teens today are less likely to want specific material goods than they were 25 years ago.

Fewer teens said it was important to have a lot of money today than did between 1988 and 1990; teens today also say it's less important to have a vacation house, own a boat or other recreational vehicle or buy a new car every few years than did in the late 1980s. But modern teens are less likely to want to work hard: During the late 1980s, just 30 percent said they didn't want to work hard.

"Entitlement has increased over time – this idea of getting something for nothing," Twenge says.