A person who criticizes the Amish farmer as being "backward" for tilling his fields with horses and a plow instead of using a tractor is displaying

ethnocentrism

Explanation:

ethnocentrism is judging other ethnic group, culture, tribe or race based on perception

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.