If it is a teaching-oriented place that's not rich, they want someone who can teach both types of classes, but whose research program is cheap (i.e. cog psych, probably not cog neuro, though maybe EEG).
If it is a research-oriented place or a richer teaching-oriented place (like top 20 usnews liberal arts colleges), then it's actually less likely to see a posting like this. For a small school (like the teaching one) they might want you to be able to teach both types of classes, but will be excited about whatever research program. For a larger school I think there is no way to know what they "really" want, but teaching isn't going to be the priority at a research-oriented place anyhow. Probably what they're looking for is whatever research program is the most fundable. Often these are the neuroscience/fMRI ones, but always; there are a lot of people in cognitive bringing in big grants, too.
So to answer your question about preference, if you're talking about a teaching oriented place then yes I think they prefer someone with a neuroscience background if that is the way the job ad is listed. But they will take the best candidate, so I wouldn't worry if you're strictly cognitive. An advantage is that you might have a better developed behavioral research program, which is also what they want.
