Official Solution:
In a recent experiment about the hypothesis that expectation influences experience of flavor, researchers conducted a taste test with over 200 participants in which each person tasted two versions of a cola beverage, one of which, they were told, contained a “secret taste-enhancing ingredient”. Because the secret ingredient was white vinegar, researchers were surprised when participants selected the white vinegar version of the cola beverage as the tastier one and concluded that the hypothesis is correct.
Of the following options which one was not assumed by the researchers to arrive at the conclusion?
A. The participants did not ordinarily prefer a cola beverage mixed with white vinegar.
B. Study participants could really identify the beverage with the “secret ingredient” from its flavor.
C. Quantity of vinegar added to the cola was not insignificant.
D. Study participants were not selected based on their preference for the taste of white vinegar.
E. Cola recipes do not contain other taste-enhancing ingredients.
Premise 1: Participants were suggested that there is a taste-enhancing ingredient in one of the beverages.
Premise 2: Participants considered the beverage with the ingredient tastier, although the ingredient was white vinegar.
Conclusion: Expectation influences experience.
A. One underlying assumption to the conclusion is that the participants do not ordinarily find white vinegar tasty. They found it tasty only because they were suggested that it was so. If they ordinarily found it tasty, then it was not because of the suggestion that they found it tasty and hence the conclusion could not have been drawn.
B. If the participants could not really identify the beverage with the extra ingredient, then their selection must have been only random and they did not really find the beverage with white vinegar tasty; thus the conclusion of the researchers would be wrong. Since negating this option breaks down the argument, this option must be an assumption.
C. This option can be eliminated using a similar reasoning as B. Saying that the amount of vinegar is
insignificant is equivalent to saying that the participants could not really identify the beverage with the extra ingredient.
D. This option can be eliminated using a similar reasoning as A. If the participants were selected because they preferred the taste of white vinegar, the argument breaks down because of the reason described in A above. Hence D must be an assumption.
E. CORRECT This option is not a necessary assumption. It is immaterial whether the colas already contain other taste enhancing ingredients. The question is about using “white vinegar” as an ingredient and whether the participants could identify the difference between normal cola (irrespective of the fact whether there are already taste-enhancing ingredients) and cola with white vinegar (and if they could identify, which one they preferred).
Answer: E
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