▁group ▁of ▁subjects ▁was ▁faced ▁with ▁remember ing ▁a ▁list ▁of ▁items ▁and ▁then ▁measured ▁when ▁trying ▁to ▁recall ▁said ▁items . ▁The ▁ev oked ▁potential s ▁and ▁hem od ynamic ▁activity ▁measured ▁during ▁encoding ▁were ▁found ▁to ▁exhib it ▁reliable ▁differences ▁between ▁subsequently ▁re called ▁and ▁not ▁re called ▁items . ▁This ▁effect ▁has ▁been ▁term ed ▁the ▁subsequent ▁memory ▁effect ▁( S ME ). ▁This ▁difference ▁in ▁these ▁specific ▁brain ▁regions ▁determ ines ▁whether ▁or ▁not ▁an ▁item ▁is ▁re called . ▁A ▁study ▁by ▁Fern ande z ▁et ▁al . ▁has ▁shown ▁that ▁the ▁differences ▁that ▁predict ▁recall ▁appear ▁both ▁as ▁a ▁negative ▁def lection ▁in ▁the ▁rh inal ▁cor tex ▁of ▁an ▁event - related ▁potential ▁( ER P ) ▁ 4 0 0   ms ▁after ▁stim ulus ▁expos ure , ▁and ▁as ▁a ▁positive ▁hi pp oc amp al ▁ER P ▁beginning ▁ 8 0 0   ms ▁after ▁stim ulus ▁on set . ▁This ▁means ▁that ▁recall ▁only ▁occurs ▁if ▁these ▁two ▁brain ▁regions ▁( rh inal ▁cor tex ▁and ▁hi pp oc amp us ) ▁are ▁activ ated ▁in ▁synchron y . ▁ ▁Fact ors ▁that ▁affect ▁recall ▁ ▁Att ention ▁The ▁effect ▁of ▁attention ▁on ▁memory ▁recall ▁has ▁surprising ▁results . ▁It ▁seems ▁that ▁the ▁only ▁time ▁attention ▁largely ▁affect s ▁memory ▁is ▁during ▁the ▁encoding ▁phase . ▁During ▁this ▁phase , ▁performing ▁a ▁parallel ▁task ▁can ▁sever ely ▁imp air ▁retr ieval ▁success . ▁It ▁is ▁believed ▁that ▁this ▁phase ▁requires ▁much ▁attention