-By Becky Ebenkamp

A recent Harris Interactive study found that three-quarters of Americans believe they are "doing their part" to keep the environment in check. It also found some interesting generational quirks among those who say they aren't.

In the May 2008 study among 2,602 U.S. adults, people checked off various personal actions they were taking to be more green compliant, such as recycling (91%), paying bills online (73%) buying locally produced food and goods (49%) and installing resource-friendly appliances (46%).

Then, Harris asked those who said they hadn't made adjustments to their lives why they hadn't, and the reasons they gave often resulted in distinct generational patterns. For instance, the most befuddled award goes to echo boomers (age 18-31), 40% of whom who said "I don't know what to do." This contrasted with 19% of the older and wiser "matures" (age 63-plus).

Now, of all the cohorts studied, the matures are the least familiar with what the term "environmental sustainability" meant--only three in 10 have heard it used--but they know to throw the Snapple bottle in the blue recycle bin.

However, those matures who said they aren't making lifestyle changes were the most jaded of the bunch: Half (49%) said these lifestyle adjustments "won't make any difference" versus 29% of refrainers of all other age groups.

Other factors for going against the green included forgetfulness (highest among echo boomers and actual boomers), "it's too expensive" (an Xers refrain) and "Don't have the time"  (echo boomers).