In an experiment, ten people were asked to taste samples of coffee and rank them. Five of the people were given chocolate with the coffee, and this group subsequently reported that all the coffee samples tasted pretty much the same as one another. Five others tasted coffee only, and they were able to detect differences. Clearly, then, chocolate interferes with one’s ability to taste coffee. Which one of the following, if true, most undermines the conclusion drawn above?
(A) The ten people were randomly assigned to either the group that tasted only coffee or the group that was also given chocolate, although some people had asked to be in the group that received chocolate.
(B) Similar results were achieved when the experiment was repeated with a different, larger group of people.
(C) Chocolate is normally consumed as a solid, whereas coffee is normally consumed as a liquid.
(D) The five people who were originally given chocolate were asked a week later to taste coffee samples without chocolate, and they still detected no differences between the coffee samples.
(E) Some subjects who tasted just coffee reported only subtle differences between the coffee samples, while others thought the differences were considerable.
A. Random assignment is a positive feature—it increases reliability. This supports the argument by reducing the chance that group differences explain the result.
B. Replicability strengthens the argument. If repeated experiments yield the same outcome, that’s a good sign the result is valid.
C. This is just a general fact about coffee and chocolate consumption. It doesn’t speak to whether chocolate affects our ability to taste differences in coffee.
D. Correct. This supports the idea that the five people who couldn’t taste any differences simply lack the ability to detect such differences, regardless of chocolate. They couldn’t taste differences with chocolate, and still couldn’t without it—suggesting it’s not the chocolate.
E. While five people is a small sample, this doesn’t explain the main result. The key finding is that the rest of the group did detect differences, while this smaller group detected none.
