Her perverseness made her deliberately give wrong answers even though she knew the right ones.

perverseness 是由形容词 perverse（任性的、固执的）加上名词后缀 -ness 构成的名词。perverse 本身含有"故意作对、违背常理"的意思，-ness 表示状态或性质，所以 perverseness 指"故意作对、任性固执的行为或性格"。