Priming. Psychological testing would be impossible without it
  and yet the priming skews results.
  [1]http://www.nature.com/.../nobel-laureate-challenges...

  Lacking reliable data and resorting to pragmatism, it's still
  better to believe it's true. I see danger signs as the "we have
  no free will, because: SCIENCE" becomes more and more the norm
  in popular culture.

  In Italian court system, they're VERY keen on "brain scans",
  even though there's fundamental issues with fMRI that really
  _should_ make them about as reliable as an ink-blot as the
  "public impression" of their accuracy is much greater than their
  real accuracy.

  Same with DNA before it.
  Same with Blood tests before it.
  etc.

References

  Visible links
  1. http://www.nature.com/news/nobel-laureate-challenges-psychologists-to-clean-up-their-act-1.11535