Berney-Reddish and Areni (2006) found that women were more likely than men (in general) to believe claims made in advertising slogans. However, this effect seemed to disappear when "probability markers" were added to the slogans. Men's belief remained fairly constant but women's belief levels dropped when these markers were added. Berney-Reddish and Areni tested both "hedge" (e.g. "probably", "may") and "pledge" (e.g. "definitely", "undoubtedly") words: both lowered claim acceptance for women.
Lori Wolin (2003) reviewed over 30 years of advertising research: some of her findings may explain this effect. Although most of Wolin's review focuses on differential reactions to gender role stereotyping and spokesperson gender effects, seven studies from 1985 to 1995 explored the "selectivity hypothesis". The selectivity hypothesis claims that "females are thought to be comprehensive information processors who assimilate all available cues while males are thought to be selective information processors who assimilate only salient cues" (Wolin).
Kempf et al (2006) went further, demonstrating that men were less likely to notice the experimental manipulations in presented information.
Well, isn't Kempf interesting? That really makes me want to look into the "hypothesis guessing" probability between men and women. Is it just harder to do research on women because they're more likely to detect what you're trying to test? As for the main question of today's post -- the believability of advertising claims is a common theme of discussion at my house. I'm a commercial-watcher. I tend to like commercials more than the actual programs half the time. Even when I was a kid, I would try to pull people into discussions about what insecurities the commercials were trying to target. There's a commercial for a weight-loss pill that runs a lot on the channels I watch that has become a running joke between me and my partner. The ad states: "we couldn't say it if it wasn't true!" I believe that's an example of a "pledge" statement, and exactly the sort of statement that makes me distrust everything else that's been said previously.