A general drive to handle and examine objects, not clearly distinguishable from the curiosity or exploratory drive.Early in this century many psychologists subscribed to the theory that the organism is motivated to act only by physiological needs such as hunger or sex. More recently, most investigators have come to believe that human beings, and animals as well, are also motivated by innate drives which are not dependent on physical deprivation. One of the most important of these drives is the need to investigate the environment by manipulating novel objects of all kinds, a need that may be almost as strong as the urge to seek food. While some psychologists still insist that this impulse can be tied to physical needs if it is analyzed down to its basic core, others believe it is a drive in its own right.The manipulation drive was first reported at the end of the nineteenth century, when observers noted that monkeys handled any new objects placed in their cages. One monkey, for example, worked unsuccessfully for two hours trying to unlock an empty trunk (Romanes, 1881), and more recently Harlow and Meyers (1950) found that monkeys would repeatedly unlock hasps on a door even though they received no reward of any kind (plate 2). Similarly, young children who are placed in a strange room with a set of toys will almost immediately start to examine and manipulate them. Piaget (1952) found that infants of four or five months of age will learn to pull a string to set a hanging rattle in motion; by five to seven months they will enjoy removing a cloth that covers their face; and between eight and ten months they will look for objects placed beneath or behind other things. In addition, ten-month-old infants will examine the shape, texture, weight, and size of objects by pounding, banging,and biting them. Brighter children usually do more exploring and manipulating than duller children.These and other observations are frequently cited in support of the idea that manipulation is an independent drive which brings its own satisfactions. While some psychologists attribute the drive to a need for stimulation—as in playing solitaire to prevent boredom—others believe it satisfies an inner urge to become acquainted with the environment. It is therefore difficult if not impossible to differentiate the manipulative drive from the curiosity drive and the exploratory drive, although attempts have been made to do so. It may well be that the three are different aspects of the same fundamental drive.But whatever the basic status of manipulation, there is no doubt that the child who is limited in his activities and kept from expressing this tendency will feel acutely frustrated and unhappy. Moreover, if he is persistently restricted he will not only fail to learn about the world, but will feel uncomfortable if not threatened by novel situations of any kind. But the child who is given ample opportunity to investigate his surroundings and play with a variety of stimulating toys will be almost certain to develop his skills and attain a sense of competence and self- confidence in dealing with both things and people. See curiosity drive, exploratory drive.