Final answer:
The investigator is testing whether the child has the concept of object permanence by showing them two balls of clay and asking if the squashed one has more clay.
Step-by-step explanation:
The investigator is testing whether the child has the b, which is the understanding that even if something is out of sight, it still exists. In this experiment, the child is shown two balls of clay of equal size and then one of them is squashed. The child is then asked whether the squashed ball has more clay than the round ball. If the child understands object permanence, they will know that squashing the ball does not change the amount of clay it contains.