The stage-IV infant's solution of problems requiring the use of supports

Piaget claimed that Stage-IV infants may pull a support to retrieve an object beyond reach, but do not understand the relation "placed upon" because they will also pull the support when the object does not rest upon it. Two experiments are reported that demonstrate Stage-IV infants do have an understanding of support, contrary to Piaget's claim. Nine-month-olds selected the appropriate support to obtain a novel rather than a familiar object, though 6-month-olds chose randomly. Nine-month-olds also retrieved an object on a support after removing an obstructing barrier, but ignored the support when the object was not placed on it. The use of an unsuitable test procedure in earlier studies may have led to the infant's competence being underestimated.