or ▁of ▁ad ul th ood . ▁Ad ult cent r ism ▁is ▁the ▁" ex agger ated ▁eg oc entr ism ▁of ▁adult s ." ▁Ad ult ocracy ▁is ▁the ▁social ▁convention ▁which ▁defines ▁" m atur ity " ▁and ▁" imm atur ity ," ▁placing ▁adult s ▁in ▁a ▁dominant ▁position ▁over ▁young ▁people , ▁both ▁theoret ically ▁and ▁pract ically . ▁Ger onto c racy ▁is ▁a ▁form ▁of ▁o lig arch ical ▁rule ▁in ▁which ▁an ▁entity ▁is ▁ruled ▁by ▁leaders ▁who ▁are ▁significantly ▁older ▁than ▁most ▁of ▁the ▁adult ▁population . ▁Chron oc entr ism ▁is ▁primarily ▁the ▁belief ▁that ▁a ▁certain ▁state ▁of ▁human ity ▁is ▁superior ▁to ▁all ▁previous ▁and / or ▁future ▁times . ▁ ▁Based ▁on ▁a ▁concept ual ▁analysis ▁of ▁age ism , ▁a ▁new ▁definition ▁of ▁age ism ▁was ▁introduced ▁by ▁I vers en , ▁Lars en , ▁& ▁So lem ▁in ▁ 2 0 0 9 . ▁This ▁definition ▁constit utes ▁the ▁foundation ▁for ▁higher ▁reli ability ▁and ▁valid ity ▁in ▁future ▁research ▁about ▁age ism ▁and ▁its ▁complexity ▁offers ▁a ▁new ▁way ▁of ▁system izing ▁theories ▁on ▁age ism : ▁" Age ism ▁is ▁defined ▁as ▁negative ▁or ▁positive ▁s tere ot ypes , ▁pre jud ice ▁and / or ▁disc rim ination ▁against ▁( or ▁to ▁the ▁advantage ▁of ) ▁elder ly ▁people ▁on ▁the ▁basis ▁of ▁their ▁chron ological ▁age ▁or ▁on ▁the ▁basis ▁of ▁a ▁per ception ▁of ▁them ▁as ▁being ▁' old ' ▁or ▁' el