The authors conclude that consumers' cognitive tendencies play a strong role in determining how they will respond to advertising. For those with a need to know, the more details, the better (assuming the details make sense, at least). There's an entirely separate population which, if given the details, will end up less likely to purchase a product.
The effect is correlated with consumers' results on the cognitive reflection test, a measure of how much thought you put into picking non-intuitive but correct answers, or in other words, how much time you might spend comparing things.