Question 17 - 20 are based on the following passage.

    Recent investigations into how children acquire knowledge about the outside world have produced agreement on one point. Children are not the blank slates imagined by philosophers since Descartes. According to leading cognitive scientists, it appears that children possess some form of innate understanding about the physical world and its concepts, such as force, heat, matter, and weight. But while scientists agree that there is some sort of initial framework present in the minds of children through which observations about the outside world are filtered and then interpreted, there is considerable disagreement over how to characterize and describe these structures.

    Some research suggests that children's innate knowledge is comprised of a number of abstract phenomenological principles. These principles provide abstractions of common events which a child can use to draw conclusions about the outside world. For example, a child might possess an inherent understanding of the force of gravity, which is represented in tile child's mind by a basic principle: if something is not supported, it falls. From this simple principle, the child can then make a number of suppositions about how gravity works on objects in the world around him.

    Other researchers believe that a child's mind comes equipped with a number of basic theories about common physical domains. These theories restrict both the type and number of viable inferences a child makes about the world, although these initial theories may then be amended by culturally acquired knowledge. Experiments have shown that when asked about the shape of the earth, very young children visualize it as a flat surface, usually a square or disc, resting on some form of support, with the inhabitants living on "top" of the surface. Such a perspective would be consistent with a child's basic experiences of the world. However, older children accurately describe the earth as a sphere floating in space, a picture that contradicts our intuitions about objects but is in accordance with the culturally and scientifically accepted views of the earth. Tellingly, none of the children in the experiment pictured the earth as a pyramid, a point, a line, or any of a number of other possible geometric forms.

The author of the passage mentions "a pyramid, a point, a line, or any of a number of other possible geometric forms" most likely in order to ....