Answer to Question 1
In the Sommers and Ellison experiment, there was no difference in sentencing for black defendants when a mock trial involved a specific statement about racial issues. On the other hand, when race was not mentioned, black defendants received longer sentences than white defendants. If there had been only one variable, the investigators would not have seen the complex pattern of results.
That is, if the researchers had only compared sentences of black and white defendants in race-salient trials, they would have concluded that race was unimportant on sentence length. If the researchers had only compared sentences of black and white defendants in non-race-salient trials, they would have concluded that race did make a difference. The truth is more complex: race sometimes makes a difference, but sometimes it doesn't. You need a factorial design to see this complexity.
Answer to Question 2
Deception is tolerable only if there is no feasible alternative and if it will not expose the participant to physical or psychological harm, including embarrassment or other discomfort. If deception is necessary, the researcher must debrief and dehoax the participant. In the end, the researcher must make sure that the participant is not negatively affected at the conclusion of the research setting. If there is any doubt, compensatory followup is required.
An example of an experiment that supported Beadle and Tatum's one gene
The experiment of Plaxton and his colleagues demonstrated that plants can alter their metabolism in
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