Michael J. Fox is a Hollywood actor with a touching life story that is known to many Americans. But Maryland Lt. Gov. Michael Steele’s sister, stricken with multiple sclerosis, speaks to people just as effectively, according to a survey of campaign ads in the Maryland Senate race by Wilson Research Strategies.

Fox, who has had Parkinson’s disease for 15 years and is an outspoken advocate for stem-cell research, caused a stir recently by speaking out for several Democratic candidates and appearing in ads for Democratic Senate hopefuls Rep. Ben Cardin in Maryland and Claire McCaskill in Missouri.

In the ads, Fox shakes uncontrollably on camera as a result of his condition. Conservative talk show host Rush Limbaugh accused him of faking it or going off his medication, later apologizing but still criticizing Fox for being a shill for Democrats.

Cardin’s opponent, Republican Michael Steele, responded with an ad featuring his sister, Dr. Monica Turner, who assures the viewer that her brother supports stem-cell research. She closes by saying that she would know, because she has MS.

While Fox scored big on the “wow” factor — his ad was rated highly for the strength of its message and its memorability, as well as its ability to generate discussion — Steele’s sister trumped him on effectiveness, appeal and credibility.

Cardin’s ad was a hit among Democrats, scoring 8.9 or above out of 10 in five of six categories. Steele’s ad, on the other hand, scored well even among members of the opposite party.

In other ads surveyed, a controversial Republican National Committee spot featuring pictures of terrorists and their comments about attacking the United States scored well among Republicans and terribly among Democrats. Republicans gave the ad an 8 for strength of message; Democrats gave it a 1.8 for credibility.

Democrat Jim Webb’s ad accusing Sen. George Allen (R-Va.) of trying to steer government contacts to a company paying him stock options bested an Allen ad warning that Webb would raise taxes and give amnesty to illegal immigrants. But neither scored well, with Allen getting a 4 for effectiveness and Webb a 4.4.

Similarly, neither Democrat Health Shuler’s pep talk in front of hay bales nor Rep. Charles Taylor’s (R-N.C.) ad accusing Shuler of accepting money from all manner of shady characters scored well. Shuler scored a 4.8 for his message, while Taylor scored a 3.9.

Working with The Hill for its Air War feature, Wilson Research Strategies e-mails campaign or issue ads to survey participants who view the ads and rate their effectiveness on several criteria.