▁the ▁student ▁as ▁a ▁rival ▁for ▁the ▁other ▁tra iner ' s ▁attention . ▁The ▁tra iner ▁and ▁model / rival ▁exchange ▁roles ▁so ▁the ▁student ▁can ▁see ▁that ▁the ▁process ▁is ▁interactive . ▁Pe pper berg ▁reported ▁that ▁during ▁times ▁when ▁she ▁and ▁an ▁assistant ▁were ▁having ▁a ▁conversation ▁and ▁made ▁mistakes , ▁Alex ▁would ▁correct ▁them . ▁ ▁This ▁technique ▁helped ▁Pe pper berg ▁succeed ▁with ▁Alex ▁where ▁other ▁scient ists ▁had ▁failed ▁in ▁facil it ating ▁two - way ▁communication ▁with ▁par ro ts . ▁In ▁later ▁years , ▁Alex ▁sometimes ▁assumed ▁the ▁role ▁of ▁one ▁of ▁Pe pper berg ' s ▁assist ants ▁by ▁acting ▁as ▁the ▁" model " ▁and ▁" rival " ▁in ▁helping ▁to ▁teach ▁a ▁fellow ▁par rot ▁in ▁the ▁lab . ▁Alex ▁sometimes ▁pract iced ▁words ▁when ▁he ▁was ▁alone . ▁ ▁Ac com pl ish ments ▁ ▁Pe pper berg ▁did ▁not ▁claim ▁that ▁Alex ▁could ▁use ▁" language ", ▁instead ▁saying ▁that ▁he ▁used ▁a ▁two - way ▁communic ations ▁code . ▁List ing ▁Alex ' s ▁accomplish ments ▁in ▁ 1 9 9 9 , ▁Pe pper berg ▁said ▁he ▁could ▁identify ▁ 5 0 ▁different ▁objects ▁and ▁recognize ▁quantities ▁up ▁to ▁six ; ▁that ▁he ▁could ▁distinguish ▁seven ▁colors ▁and ▁five ▁shapes , ▁and ▁understand ▁the ▁concepts ▁of ▁" b igger ", ▁" small er ", ▁" same ", ▁and ▁" d ifferent ", ▁and ▁that ▁he ▁was ▁learning ▁" over " ▁and ▁" under ". ▁Alex ▁passed ▁increasing ly