Official Solution:
In a research study, participants were asked to choose between two brands of a certain type of product: one familiar, one unfamiliar, and report their choice to the researchers. Before making the choice, one group was told emphatically to hurry, as the researchers were behind schedule and pressed for time; the other group was told that the project was ahead of schedule, giving them ample time to make the decision. Every participant in the former group, but only about two-thirds of the latter group, chose the familiar brand. Since the participants self-reported equal amounts of stress in their current lives, the researchers concluded that the sight of a well-known product countered the extra stress of being rushed for the first group. The soundness of this conclusion, however, cannot be assessed without taking into account _________.
Which of the following most logically completes the argument above?
A. any differences in the frequency or geographic span of the two brands’ advertising
B. how much participants enjoyed or valued the activities most commonly associated with the products
C. the degree of importance ascribed to the product by the researchers in their instructions to the participants
D. the nature of the events or situations causing stress in the participants’ lives outside of the experiment
E. the number of factors that participants thought necessary to consider in judging the unfamiliar product relative to the familiar one
The passage mentions only one known distinction between the two experimental groups: one group was given a stressful situation (the experimenter's reminder about time pressure) and the other wasn't. The author of the passage takes it as given that the the former group's unanimous choice of the familiar brand was a direct counter-response to the extra stress imposed on them. The issue is that the added stress isn't the only thing that could explain the first group's unanimous choice of the known product. Perhaps some other aspect of the time pressure led that group into choosing an already-familiar product, particularly if there was something they considered necessary to a well-considered decision that they just didn't have the time to do. In any case, the correct answer will be the one that provides some OTHER mechanism - i.e., NOT involving stress levels, by which the time pressure imposed on the first group drove them to choose the product with which they were already familiar.
(A) Although this choice may help to explain why one brand is more or less familiar than the other, those reasons are irrelevant. It matters only that one brand is more familiar; it doesn't matter why. The argument is concerned solely with why the experimental participants chose the brand that was familiar, not with the reasons behind the familiarity itself.
(B) Since the participants were presented with two different brands of the same type of product, the activities associated with the two products would be the same. Therefore, this consideration cannot possibly explain any asymmetrical reactions by the participants.
(C) The validity of the argument is unaffected by whether the product is presented or perceived as "important." The argument is concerned only with differences in the participants' choices between familiar and unfamiliar products, not between "important" and "unimportant" products.
(D) The passage states that "the participants self-reported equal amounts of stress in their current lives." Therefore, even if that outside stress came from various sources, it would not have a greater aggregate effect on one group than on the other. Therefore, the source of the groups' outside stress does not affect the argument.
(E) CORRECT. According to the author, the "time pressure" group selected the familiar brand because its familiarity provided comfort against the stress of the situation. However, if the participants saw the judgment as depending on a large number of factors, then they may just as well have decided that there wasn't time to consider all of those factors. If that's the case, then the participants could just as well have chosen the familiar brand simply because they didn't have time to form an adequate judgment of the unfamiliar brand.
Answer: E