An experiment was conducted to compare the effectiveness of head restraints modified to increase the likelihood of eliciting uninstructed adjustments from a non-use to a deployed position among naïve users. Fifty-nine participants aged 18-46 years experienced one of three head restraint conditions. The first condition consisted of an unmodified, original equipment (OE) second- row head restraint from a 2009 Ford Flex, which was compliant to specifications in the United Nations’ Global Technical Regulation (GTR) No. 7 intended to provide distinct physical cues to alert occupants to the need to adjust the head restraint. The second condition consisted of an OE head restraint modified to be longer vertically, which also met the GTR specifications. Lastly, a thicker head restraint producing a torso angle change of 10 degrees from the seat back (10 degrees), one of multiple compliance options allowed in FMVSS No. 202, was examined.
http://www.nhtsa.gov/DOT/NHTSA/NVS/Crashworthiness/head%20restraints/811514.pdf
