British researchers randomly assigned 424 hospitalized premature infants either to formula feeding or to breast-milk feeding. Th
ey found that on intelligence tests taken at the age of 8, those who were breast fed significantly scored higher than those who were formula fed. These researchers conducted a(n):
The experiment allows the researcher to deliberately apply a treatment before observing any of the responses. In this case, there was a procedure done to discover an unknown fact. It had controlled conditions in order to establish a hypothesis.
