( ( When ( shape ( only ( is ( used ( as ( ( a discriminator ) ( for figures ) ) ) ) ) ) ) ) ( , ( ( convex shapes ) ( ( ( will likely ) ( be ( ( perceived ( as ( figures ( and ( concave shapes ) ) ) ) ) ( as holes ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NN shape)) (ADVP (RB only)) (VP (VBZ is) (VP (VBN used) (PP (IN as) (NP (NP (DT a) (NN discriminator)) (PP (IN for) (NP (NNS figures))))))))) (, ,) (NP (NN convex) (NNS shapes)) (VP (MD will) (ADVP (RB likely)) (VP (VB be) (VP (VBN perceived) (PP (IN as) (NP (NNS figures) (CC and) (NN concave) (NNS shapes))) (PP (IN as) (NP (NNS holes)))))) (. .)))
When shape only is used as a discriminator for figures, convex shapes will likely be perceived as figures and concave shapes as holes.
(ROOT (S (NP (DT A) (NN convex) (NN mirror)) (VP (VBZ is) (VP (VBN shaped) (PP (IN like) (NP (NP (DT the) (NN outside)) (PP (IN of) (NP (DT a) (NN bowl))))))) (. .)))
A convex mirror is shaped like the outside of a bowl.