Scientists performed an experiment to determine whether there is a connection between learning ability and food. They took two groups of 20 mice each, all from the same purebred strain. The mice were deprived of food for 3 days and then given a standard learning session in running through a maze. They were trained by giving them a mild electric shock whenever they took a wrong turn. Immediately after each learning session, one group of mice was fed, but the other was not, A week later, all of the mice were tested to see whether they could still run the maze correctly. The group that had been fed had retained this ability, but the other group had not. The probable reason that the scientists used only mice from the same pure-bred strain is so that?

The scientists used mice from the same purebred strain to ensure that any differences observed in learning ability and food connection can be attributed to the experimental manipulation (feeding/not feeding) rather than genetic variations between different strains of mice. By using mice from the same purebred strain, the scientists could minimize genetic differences that could potentially influence learning ability and food connection. This is important because if they had used mice from different strains, it would be difficult to determine whether the observed differences were due to the feeding manipulation or inherent genetic differences between the strains. Using mice from the same purebred strain increases the internal validity of the experiment, allowing for more accurate conclusions about the connection between learning ability and food.