"I can do small things every day that will make an impact on water pollution."

It's such a simple statement, and it's true. So why is it so hard to send a message -- over the airwaves, online, or in print -- that actually evokes that reaction? Unfortunately, many environmental messages accidentally evoke an entirely different reaction, instead:

"It is hard to believe that the actions of one person can really contribute to lessening water pollution."

I pulled those quotes from test audiences that reviewed a pair of environmental public service announcements. It's my job to help environmental organizations pre-test their commercials and other marketing materials before they are released to the public.

The two spots had a lot in common. Both of them urged everyday citizens to do their part in their daily lives to stop water pollution before it starts. But here's the key difference -- the producers of more successful advertisement crafted their message to encouraging. The producers of the less successful advertisement crafted their message to be educational.

Tennessee Water Works produced the "Heroes" advertisement, which prompted that confident "I can do small things every day" response. Who are the "heroes" this ad is about? People like you and me, who plant trees, recycle their motor oil (instead of dumping it in the drain), and care for their lawns responsibly. This advertisement holds up the example of ordinary people doing ordinary things and tells the viewer how great it is.

In just 30 seconds, the advertisements repeatedly send the message that these people are heroes and their small actions add up to something important. According to the test panel, this message eventually sinks in.

The government of Honolulu produced the "Water for Life" commercial that prompted the second, doubt-filled reaction. This spot is educational. It shows images that reveal how trash and pollution find their way into storm drains and out into the ocean that Hawaiians love.

Sure, it's true. But it's grim -- bumming the viewers out with shots of murky, polluted water, garbage, and choking wildlife. According to the test audience feedback, viewers see reason to believe that solutions are within reach, or that they have a part to play in bringing it about.

Environmental experts are often dismayed at how little the average citizen understands about their work. It's easy to find yourself falling into the "if only they knew" trap -- "If only they knew they lived in a watershed," "if only they knew the stormdrain went to the creek." It is our natural tendency to produce commercials, web pages, brochures, and other materials that try to cram a whole of science into a tiny amount of attention.

But the test panel reactions to these commercials underscore the shortcomings of these line of thinking. When it comes to raising environmental awareness, it turns out encouragement is even more important than education.