9 9 2 , ▁the ▁population ▁of ▁cod ▁had ▁completely ▁col lapsed ▁because ▁fish ers ▁had ▁not ▁left ▁enough ▁fish ▁to ▁rep op ulate ▁the ▁species . ▁ ▁Social ▁tra ps ▁ ▁A ▁social ▁trap ▁occurs ▁when ▁individuals ▁or ▁groups ▁purs ue ▁immediate ▁re wards ▁that ▁later ▁prove ▁to ▁have ▁negative ▁or ▁even ▁le th al ▁consequences . ▁This ▁type ▁of ▁d ile m ma ▁ar ises ▁when ▁a ▁behavior ▁produces ▁re wards ▁initially ▁but ▁continu ing ▁the ▁same ▁behavior ▁produces ▁dimin ishing ▁returns . ▁Stim uli ▁that ▁cause ▁social ▁tra ps ▁are ▁called ▁sl iding ▁rein for cers , ▁since ▁they ▁rein force ▁the ▁behavior ▁in ▁small ▁dos es ▁and ▁pun ish ▁it ▁in ▁large ▁dos es . ▁ ▁An ▁example ▁of ▁a ▁social ▁trap ▁is ▁the ▁use ▁of ▁vehicles ▁and ▁the ▁resulting ▁air ▁poll ution . ▁View ed ▁individually , ▁vehicles ▁are ▁an ▁adapt ive ▁technology ▁that ▁have ▁revolution ized ▁transport ation ▁and ▁greatly ▁improved ▁quality ▁of ▁life . ▁But ▁their ▁current ▁w ides p read ▁use ▁causes ▁negative ▁external ities . ▁In ▁many ▁places ▁air ▁poll ution ▁continues ▁un ab ated ▁because ▁the ▁convenience ▁of ▁driving ▁a ▁car ▁is ▁immediate ▁and ▁the ▁environmental ▁costs ▁are ▁distant ▁and ▁often ▁do ▁not ▁become ▁obvious ▁until ▁much ▁later . ▁ ▁Per cept ual ▁d ile m ma ▁ ▁A ▁per cept ual ▁d ile m ma ▁ar ises ▁during ▁conflict ▁and ▁is ▁a ▁product ▁of ▁out group ▁bias . ▁In ▁this ▁d ile m ma , ▁the ▁parties ▁to ▁the ▁conflict ▁prefer ▁co