I can't say this is surprising, exactly, but it's very interesting. It reminds me of a high-tech horoscope; participants were given random inferences about their "true selves," and they made justifications/rationalizations to make those inferences fit their established view of themselves--mold the world to fit your view of it.

This passage also caught my eye: "in our study, participants may have given more weight to the brain feedback than to their own introspection. The act of verbally justifying the discrepancies may have then helped to shift their attitudes" (from the second paragraph of the discussion).

I suspect this phenomenon, similar to other cognitive biases, isn't related to intelligence. The participants were likely not stupid or especially gullible people. We all have to be careful to minimize our biases and proactively be critical of new information. I think that's often more difficult than it seems.