▁lab . ▁ ▁Crit ic isms ▁▁ ▁Some ▁in ▁the ▁scientific ▁community ▁are ▁ske pt ical ▁of ▁Pe pper berg ' s ▁find ings , ▁pointing ▁to ▁Alex ' s ▁communic ations ▁as ▁oper ant ▁condition ing . ▁Crit ics ▁point ▁to ▁the ▁case ▁of ▁Cle ver ▁Hans , ▁a ▁horse ▁who ▁could ▁apparently ▁count , ▁but ▁who ▁was ▁actually ▁understanding ▁subt le ▁c ues ▁from ▁the ▁question er . ▁ ▁In ▁another ▁case , ▁N im ▁Ch im ps ky , ▁a ▁ch imp anze e , ▁was ▁thought ▁to ▁be ▁using ▁language , ▁but ▁there ▁is ▁some ▁debate ▁over ▁whether ▁he ▁simply ▁im itated ▁his ▁teacher . ▁Herbert ▁Terra ce , ▁who ▁worked ▁with ▁N im ▁Ch im ps ky , ▁says ▁he ▁thinks ▁Alex ▁performed ▁by ▁ro te ▁rather ▁than ▁by ▁using ▁language ; ▁he ▁calls ▁Alex ' s ▁responses ▁" a ▁complex ▁disc rimin ating ▁performance ", ▁adding ▁that ▁in ▁every ▁situation , ▁" there ▁is ▁an ▁external ▁stim ulus ▁that ▁gu ides ▁his ▁response ." ▁However , ▁supp or ters ▁of ▁Alex ▁say ▁he ▁was ▁able ▁to ▁talk ▁to ▁and ▁perform ▁for ▁anyone ▁involved ▁in ▁the ▁project ▁as ▁well ▁as ▁complete ▁str angers ▁who ▁recorded ▁find ings , ▁though ▁such ▁interactions ▁do ▁not ▁involve ▁the ▁strict ▁conditions ▁required ▁to ▁exclude ▁ro te ▁and ▁oper ant ▁respond ing . ▁ ▁See ▁also ▁ ▁References ▁ ▁External ▁links ▁▁ ▁Alex ▁Foundation ▁ ▁Ob itu ary ▁article ▁at ▁the ▁web - site ▁of ▁The ▁Econom ist ▁magazine ▁ ▁NY ▁Times ▁ob