We investigated whether great apes, like human infants, monkeys and dogs, are subject to a strong gravity bias when tested with the tubes task, and--in case of mastery--what the source of competence on the tubes task is. We presented 22 apes with three versions of the tubes task, in which an object is dropped down a tube connected to one of three…

In manual search tasks designed to assess infants' knowledge of the object concept, why does search for objects hidden by darkness precede search for objects hidden by visible occluders by several months? A graded representations account explains this decalage by proposing that the conflicting visual input from occluders directly competes with…

Infants who were in darkness were presented with objects that made sounds. Objects were within reach and out of reach. Infants reached into the target area more often when the object was in reach than when the object was beyond reach. Infants reached correctly in the dark for objects placed off midline. (BC)