I was reviewing a paper, which I thought was overall pretty strong. I thought there was an interesting connection to some paper from Alice Smith (not the author's real name) in the past few years and mentioned this in my review. Not a connection that made the current paper irrelevant, but something the authors should probably talk about. In the revision response, the authors said that they had looked to try to find Smith's paper, but could figure out which one I was talking about, and asked for a pointer. I spend the next five hours looking for the reference and couldn't find it myself. It turns out that actually I was thinking of a paper by Bob Jones, so I provided that citation. But the Jones paper wasn't even as relevant as it seemed at the time I wrote the review, so I apologized and told the authors they didn't really need to cover it that closely.
Now, you might be thinking to yourself: aha, now I know that Hal was the reviewer of my paper! I remember that happening to me!
But, sadly, this is not true. I get reviews like this all the time, and I feel it's one of the most irresponsible things reviewers can do. In fact, I don't think a single reviewing cycle has passed where I don't get a review like this. The problem with such reviews is that it enables a reviewer to make whatever claim they want, without any expectation that they have to back it up. And the claims are usually wrong. They're not necessarily being mean (I wasn't trying to be mean), but sometimes they are.
Here are some of the most ridiculous cases I've seen. I mention these just to show how often this problem occurs. These are all on papers of mine.
- One reviewer wrote "This idea is so obvious this must have been done before." This is probably the most humorous example I've seen, but the reviewer was clearly serious. And no, this was not in a review for one of the the "frustratingly easy" papers.
- In a NSF grant review for an educational proposal, we were informed by 4 of 7 reviewers (who each wrote about a paragraph) that our ideas had been done in SIGCSE several times. Before submitting, we had skimmed/read the past 8 years of SIGCSE and could find nothing. (Maybe it's true and we just were looking in the wrong place, but that still isn't helpful.) It turned out to strongly seem that this was basically their way of saying "you are not one of us."
- In a paper on technique X for task A, we were told hands down that it's well known that technique Y works better, with no citations. The paper was rejected, we went and implemented Y, and found that it worked worse on task A. We later found one paper saying that Y works better than X on task B, for B fairly different from A.
- In another paper, we were told that what we were doing had been done before and in this case a citation was provided. The citation was to one of our own papers, and it was quite different by any reasonable metric. At least a citation was provided, but it was clear that the reviewer hadn't bothered reading it.
- We were told that we missed an enormous amount of related work that could be found by a simple web search. I've written such things in reviews, often saying something like "search for 'non-parametric Bayesian'" or something like that. But here, no keywords were provided. It's entirely possible (especially when someone moves into a new domain) that you can miss a large body of related work because you don't know how to find in: that's fine -- just tell me how to find it if you don't want to actually provide citations.
I'm posting this not to gripe (though it's always fun to gripe about reviewing), but to try to draw attention to this problem. It's really just an issue of laziness. If I had bothered trying to look up a reference for Alice Smith's paper, I would have immediately realized I was wrong. But I was lazy. Luckily this didn't really adversely affect the outcome of the acceptance of this paper (journals are useful in that way -- authors can push back -- and yes, I know you can do this in author responses too, but you really need two rounds to make it work in this case).
I've really really tried ever since my experience above to not ever do this again. And I would encourage future reviewers to try to avoid the temptation to do this: you may find your memory isn't as good as you think. I would also encourage area chairs and co-reviewers to push their colleagues to actually provide citations for otherwise unsubstantiated claims.