Yes, that's what I meant. (Believe me, I know it's not a behavior I spent 5 long years getting a psych degree) It was a quick reply. I was just saying that cognitive dissonance is not the right term for what you were ascribing to the reason for the behavior of voting down a review because it doesn't conform with their opinion.
Ah. Well, I didn't intend to say that; in fact I said this, which I think is the opposite of that, haha:
However in terms of the actual voting process, refusing to recommend something just because you disagreed with its conclusion has nothing to do with dissonance; it has to do with you not wanting an opposing view to be seen as valid (note that cognitive dissonance is a disparity between your own beliefs and actions, not your beliefs and someone else's actions).
But if I came across as implying what you said, then by all means I'm glad to have misinformation dispelled.
I honestly have no idea why people down-vote negative reviews more frequently (as you say you've observed; again, I think it would be nice to actually see data on it -- for all we know your personal experience has just been an anomaly). If we assume that people who click "not recommended" tend to do so more because they disagree with your opinion than because the review was poor, then the question is: how do your tastes align with popular tastes? Do you routinely have a less optimistic view of something which a majority of people like? If so, your pool of people who would disagree with the negative review (and thus feel inclined to negatively assess said review) is larger.