Karmakar and Tormala on Certainty and Persuasion

I'm no expert on psychology or source certainty. But I am certain that this article by Uma Karmarkar and Zakary Tormala is worth looking at. The title is, Believe Me, I Have No Idea What I Am Talking About: The Effects of Source Certainty on Consumer Involvement and Persuasion, and the citation is Journal of Consumer Research 36, no. 6 (2010): 1033–1049. (I got the information on the full citation here.)

Here is the abstract:

This research explores the effect of source certainty-that is, the level of certainty expressed by a message source-on persuasion. The authors propose an incongruity hypothesis, suggesting that source certainty effects depend on perceived source expertise. In three experiments, consumers receive persuasive messages from sources of varying expertise and certainty. Across studies, low expertise sources violate expectancies, stimulate involvement, and promote persuasion when they express certainty, whereas high expertise sources violate expectancies, stimulate involvement, and promote persuasion when they express uncertainty. Thus, nonexpert (expert) sources can gain interest and influence by expressing certainty (uncertainty).

I wonder if law students with blogs would be able to express certainty for persuasion's sake without running up against rules prohibiting the unauthorized practice of law. While I have my disclaimers page here that warns readers that nothing I say is advice, I wonder if too-certain statements elsewhere in the blog would negate my warnings. This is inconvenient from a persuasion perspective, since the disclaimer page probably establishes I am a non-expert.