Bruner’s studies helped to introduce Piaget’s concept of developmental stages of cognition into the classroom. His much-translated book The Process of Education (1960) was a powerful stimulus to the curriculum-reform movement of the period. In it he argued that any subject can be taught to any child at any stage of development, if it is presented in the proper manner. According to Bruner, all children have natural curiosity and a desire to become competent at various learning tasks; when a task as presented to them is too difficult, however, they become bored. A teacher must, therefore, present schoolwork at a level so as to challenge the child’s current developmental stage. Bruner also studied perception in children, concluding that children’s individual values significantly affect their perceptions.