To try this experiment, install a cookie manager extension like "Edit This Cookie" for Chrome or Cookies Manager+ for Firefox, go to google.com and change the value of the NID cookie to:
67=Pj2b01uyf7hJnPvNoPECEnzlbCoXch_13GxuSVeSSyRdm_irfKzVaizXIE5svj3Qw1985iU4waenQh_Qy-BrE4WOtZ5Zoz9T4Kl1e1DtwJL4Xy0-JBcW_Z9IOKdd1H5Z
If you use "Edit This Cookie", don't forget to click "Submit changes". Delete the NID cookie to opt-out from the experiment.
{ Thanks, Rubén. }