The ability to change opinions is an important difference between rational and overly stubborn people.
Sometimes I can be convinced during a discussion. Then people are often very surprised that I change my opinion at all. Then I wonder why the bother to discuss, if they don't expect me to actually change my opinion.
Well, if you change your opinion, that means you were WRONG! And being wrong is... well... WRONG! Don't you see?! You can't let people see you being wrong, man! They might think you're human!
So much of the media we consume is heavily editorialized to hit an emotional chord. This makes sense from the author's perspective - an argument with a strong pathos can help it get noticed. I will often react instinctively at first, then take some time and reconsider and form a different opinion. Sometimes I read an article on HN, then go to the comments where someone states a counterpoint I had not considered. Especially on a this forum, one should have the chance to change a vote.
I think it's unlikely that that would be necessarily. Only a small minority of votes would be reversed, and the even smaller portion of those that are reversed a second time wouldn't be worth worrying about.
It has to be more than just a solution: it has to be a solution that requires close to zero coding from time-constrained PG.
I think adding a hover effect to the arrow would provide the most benefit per second coding. The following line of CSS can do it without requiring image editing:
a:hover img {opacity: .6;}
That gives a little feedback about what irrevocable action is about to take place – which is especially useful when mousing the area in between the arrows, where currently a single pixel of movement can invisibly turn an intended upvote into a downvote.
Other solutions are better, but this is an easy 80% one.
(edit) Having actually thought about it for a minute, I think a simple "Undo last vote" in the title bar next to the account name would work just fine for reversing accidental votes. And, say, call it unvote for brevity. I really like how clicking on either arrow makes them disappear, this is very much in line with general minimalistic design of the site, so I would rather have it stay.
It's a good idea. But its side effect could be that people are more encouraged to write replies instead of just voting (resulting in too many me-too comments). We will never know without trying it out though.
An alternative is to have the arrows straddle the top line of a comment instead. The down-vote button will be right beside the 'flag' link which may or may not have a desired side effect.
Yet another idea with possibly least side effect is to have them straddle '[x] points'.
Well on my screen the arrows go from the top of the line showing points and user name, to halfway down the first line of comment text.
Every comment has to have at least 1 line of text, why not make the arrows go from the top of the user line to the bottom of the first comment text line. That is about a 25% increase in size.
