Psychologists have studied the impact a person’s attitude has on his

Even i have the same issue.

Hi,

To those that are asking why E could not be the answer. I had the same doubt but on careful reading of the E:

(E) many of the participating students suffer from tension headaches which readily respond to the heat pulses

The students may respond favourably or unfavourable to the heat pulses; We just don't know. Also, the crux of the passage is in how an aspect can "frustrate" the experiment i.e. evaluating the effects of attitude on ability. Regardless, of how many students react to the heat pulses does not create any bias in evaluating results and thus does not "frustrate" the parameters of the experiment.

Maybe, heat pulses can later be studied on their effect on students but their mere existence does not create any visible bias in the experiment. However, (A) creates a visible bias as has been explained in OA and this bias can frustrate / break the objectivity in the experiment.

Also, the contraption works on 50% so even if "many" students face tension headaches, what if this "many" fall in the other 50% category where the contraption does NOT work. So you see that there are too many variables to factor with (E) and hence, cannot be the option.

Hope this helps.

Psychologists have studied the impact a person’s attitude has on his ability to accomplish tasks. In one study, a group of college students was outfitted with contraptions designed to administer soothing heat pulses to the students’ neck and shoulder muscles. The students were told that the pulses would enhance their performance of in-class assignments. Only half of these contraptions worked, but neither the students nor the psychologists were told which students would actually receive these pulses. This component of the experiment is often frustrated, however, because

Which one of the following selections, if it is true, completes the sentence most appropriately?

(A) frequently the faces of the students who actually receive the pulses become a little flushed. - CORRECT. POE helps. But flushed faces must confuse students and psychologist alike, so that bias, if any, is not there.

(B) students who believe they are receiving the warm pulses do better on their class assignments. - WRONG. This should not frustrate rather prove the point.

(C) students who participate in the studies are volunteers who must be told that some of them will not receive the heat pulses. - WRONG. The very nature on which the experiment depends is destroyed by this choice.

(D) many students will not complete the experiment if the sessions last too long. - WRONG. Issues with "many". Also, not completing is out of picture.

(E) many of the participating students suffer from tension headaches which readily respond to the heat pulses. - WRONG. Two red text are problems that this option suffers from. Many may stand for(2 or 3 students, or for half of the students) those for whom these contraptions didn't work and equally for those for whom these contraptions worked. Ready response for whom is also a big question.

Answer A.