"No One Knows What Science Doesn't Know" seems relevant here. I know that there has been a lot of followup literature on the Wason task (e.g. chapter four of David Buller's evopsych critique Adapting Minds devoted a lot of space to an alternative explanation of the Wason task, and Cosmides et al. have responded to critics (PDF), &c., &c.), but if any conclusion was definitively reached, I can't say what it was. Oh, what I would only give for a thousand years of library time---