Interestingly, research supports the logic that a direct comparative ad from a small-share market follower is least likely to lead to higher awareness for the compared-to market leader (because the market leader already has high awareness), whereas a market-leading high-share brand has the most to lose from a direct comparative ad (by creating “free” awareness for the compared-to smaller brand). This leads to the conclusion that while low-share brands ought to use direct comparative ads; market leaders perhaps ought to use noncomparative or indirectly comparative ads (those that don’t name competitors).

Smaller-share market follower brands also stand to gain more from direct comparative ads in another way: such ads have the effect of getting consumers to put both the advertised and the comparison brand in the same “consideration set,” by increasing the degree to which they are perceived as similar to each other. A study found that comparative advertising was much more effective than non-comparative advertising in increasing the perceived similarity of the challenger and leader brands, particularly when the leading brand was explicitly named in the ad.

However while a comparative did bridge the perceived “distance” between the “leader” and the “challenger” brand, it did not significantly raise the attitude toward the advertised brand. Many other studies have also failed to find such attitude-enhancing effects. These failures could be due, in part, to the fact that these studies often failed to measure (and could not therefore find) possible decreases in consumers’ attitudes toward the comparison brand. It has also been shown, however, that comparative ads often fail to sway attitudes and preferences because, while people may indeed notice them more, they nonetheless may consider a comparative ad offensive, less credible and less informative (especially if they happen to like the brand being shown in a negative light.) The consumers’ liking for a brand does go up due to comparative advertising but only upto a certain point.