▁studies ▁have ▁challeng ed ▁these ▁claims , ▁finding ▁little ▁correlation ▁between ▁n erve ▁condu ction ▁velocity ▁and ▁reaction ▁time ▁( RT ). ▁ ▁R aven ' s ▁Progress ive ▁Mat rices ▁R aven ' s ▁Progress ive ▁Mat rices ▁( R PM ) ▁is ▁a ▁test ▁consisting ▁of ▁ 6 0 ▁multiple - choice ▁questions ▁that ▁increase ▁in ▁difficulty . ▁R PM ▁is ▁based ▁off ▁pattern ▁recognition ▁and ▁is ▁a ▁non ver bal ▁group ▁test , ▁requiring ▁the ▁test ▁tak er ▁to ▁identify ▁the ▁missing ▁element ▁that ▁comple tes ▁the ▁pattern . ▁The ▁test ▁is ▁designed ▁to ▁measure ▁reasoning ▁ability . ▁The ▁results ▁of ▁these ▁tests ▁are ▁then ▁pa ired ▁with ▁the ▁results ▁of ▁imag ing ▁studies ▁and ▁relationships ▁are ▁drawn ▁i . e . ▁higher ▁R PM ▁scores ▁and ▁the ▁increased ▁size ▁of ▁a ▁specific ▁brain ▁structure . ▁ ▁R aven ' s ▁Advanced ▁Progress ive ▁Mat rices ▁R aven ' s ▁Advanced ▁Progress ive ▁Mat rices ▁( R AP M ) ▁is ▁a ▁ 3 6 - item ▁test ▁used ▁to ▁measure ▁g F . ▁R AP M ▁tests ▁for ▁differences ▁in ▁novel ▁problem ▁solving ▁and ▁reasoning ▁ab ilities . ▁Similar ▁to ▁the ▁R PM , ▁subjects ▁complete ▁the ▁pattern , ▁ident ifying ▁the ▁missing ▁piece ▁of ▁a ▁ 3 x 3 ▁matrix ▁from ▁a ▁list ▁of ▁eight ▁options . ▁ ▁n - Back ▁Working ▁Memory ▁( WM ) ▁task ▁The ▁n - back ▁WM ▁task ▁has ▁commonly ▁util ized ▁to ▁measure ▁cogn itive ▁activity ▁during ▁ne uro im aging .