Which historical events led to the united states becoming a world superpower? a. the abolition of slavery after the civil war
b. the colonial victory after the revolutionary war
c. the purchase of Louisiana from France
d. the allied victory in ww2

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.        

the telephone is the answer

answer; ///biological psychologists;