GMAT Critical Reasoning – Trap Choices Versus Correct Answers

There are multiple aspects to arriving at the correct answer to a GMAT Critical reasoning question. Among them are completely understanding the stimulus, finding and clearly understanding the conclusion, noting exactly what the question stem is asking, and noting key details in the stimulus and answer choices.

One aspect that does not get talked about as much as some of the others is the final key step, telling the difference between trap choices and the correct answer to the question. The reason this step is important is that, even if you know what the passage is about, totally understand the conclusion, and are ready to find the correct answer, it can be easy to fall into one of the mental traps that the GMAT has set in the form of one or more answer choices that seem to answer the question but don’t quite get the job done.

If you aren’t skilled in telling the difference between these trap choices and correct answers, you’ll be constantly stuck with fifty-fifty choices, and you may choose wrong a lot of the time. If you are good at telling the difference, and you carefully handle the other aspects of getting the correct answer to a Critical Reasoning question, you will get Critical Reasoning questions right consistently.

So, let’s discuss how to tell the difference between trap choices and the correct answer to a Critical Reasoning question in the context of an example.

For a study, people experiencing depression were placed into two groups, the Exercise Group and the Control Group. The people in the Exercise Group were given support for creating and following an exercise program, with the result that 50 percent of those in the Exercise Group reported getting regular exercise, while those in Control Group were given no such support. After a year, there was little difference between the average level of depression seen in members of the Exercise Group and that seen in members of the Control Group. Clearly, exercise is not effective in mitigating depression.

Which of the following, if true, most seriously undermines the force of the evidence cited?

(A) The members of the Exercise Group did not all use the same forms of exercise.

(B) A significant proportion of the members of the Exercise Group were considered no longer depressed after a year.

(C) The physiological effects of vigorous exercise are in some aspects quite different from those of light exercise.

(D) Endorphins, chemicals released by the body during exercise, can contribute to a person’s having a positive outlook on life.

(E) Typically, about 45 percent of people choose to exercise regularly.

Since this question asks us to find the choice that undermines the force of the evidence cited, we can tell that it is a Weaken the Argument question.

Now, here’s the thing, the correct answer won’t be a choice that merely, in some vague way, seems to conflict with the conclusion or some other aspect of the argument. GMAT Critical Reasoning correct answers are correct because they do exactly what the question asks for, and the reason why the correct answer to this question is correct is something that we can very clearly define using logic.

Along with the correct answer to this question are some trap choices, and, unlike the correct answer, the trap choices don’t really affect the argument in the way the correct answer has to, but they can certainly seem to. Since this is a Weaken question, the trap choices are written to seem to conflict with the information that provides support for the conclusion, and thus, if we use vague thinking rather than tight logic, we can end up choosing one of the trap choices.

Here’s the conclusion the support for which we have to weaken:

Conclusion: Exercise is not effective in mitigating depression.

Now let’s consider the answer choices, and differentiate between trap choices and the correct answer.

(A) The members of the Exercise Group did not all use the same forms of exercise.

This choice is a trap. Notice how this choice could be tempting. If we read this choice using vague thinking, it can seem to somehow weaken the support for the conclusion. We might think something along the lines of, “The conclusion is that exercise is not effective in mitigating depression, but these people didn’t even use the same types of exercise. So, this study is flawed, and so, this choice weakens the argument.”

That kind of thinking is not going to work well for us. It’s not tightly logical thinking. It’s just thinking based on some vague idea along the lines of, if the types of exercise are not all the same, then we don’t really know what’s going on. The truth is that the study parameters are very simple – exercise versus no exercise. The type of exercise does not matter. Employing that tightly logical thinking, we can eliminate this choice and avoid being trapped.

(B) A significant proportion of the members of the Exercise Group were considered no longer depressed after a year.

This choice is a trap as well. Notice how, using vague thinking, we could end up choosing this trap choice. We could give ourselves the impression that the fact that a significant proportion of the members of the Exercise Group were considered no longer depressed after a year means that the exercise actually worked. “Hey, this is significant! The exercise worked, and this choice destroys the argument.”

The truth is, however, that that thinking is not logical enough.

If we consider what the passage says, we notice that the evidence used is the average levels of depression. So, if we use tightly logical thinking, we won’t pick this trap choice, because we can see that it changes nothing. Sure, some people in the Exercise Group were no longer depressed, but, on average, the levels of depression of the people in the two groups were the same.

We have to notice details like the fact that the conclusion is based on average levels of depression in order to avoid choosing trap choices.

(C) The physiological effects of vigorous exercise are in some aspects quite different from those of light exercise.

Perhaps this choice could be spun into a story that seems to weaken the argument, but really, this choice is not much of a trap because what it says is only loosely connected to what the argument is about.

(D) Endorphins, chemicals released by the body during exercise, can contribute to a person’s having a positive outlook on life.

This choice is the trickiest trap in this question, as, if we are not super logical in our thinking, we could perceive this choice as directly conflicting with and destroying the argument. We might choose this choice because it seems to clearly indicate that exercise is in fact effective in mitigating depression. “Look at this. Exercise results in a person’s having positive outlook on life. So, it clearly serves to mitigate depression.”

If we were to choose this choice, we would have been sucked in by a trap written to seem to weaken the argument.

So, how do we avoid getting trapped? We use thinking that is tightly logical, rather than rely on a vague perception that an answer does what we need. We keep in mind exactly how the argument is supported, in this case by data on average levels of depression, and notice that what this choice says actually changes nothing about the support for the argument. After all, even if chemicals released during exercise can contribute to a person’s having a positive outlook on life, the people in the exercise group were still no less depressed than the people in the control group. So, the evidence and the support for the conclusion provided by that evidence are not changed by what this tempting trap choice says.

Now, let’s consider the correct answer.

(E) Typically, about 45 percent of people choose to exercise regularly.

Notice the difference between this choice and the trap choices. Whereas the trap choices are written to seem to weaken the argument, this choice is written to seem to have almost no bearing on the argument. One could think, “So what if people exercise regularly. This is irrelevant.”

However, if we were to manage to use tight logic to avoid being trapped by other choices, we would be pretty sure that this is the correct answer, and so, we would have to figure out why.

As it turns out, this choice is correct because, if, typically, about 45 percent of people choose to exercise regularly, then it could very well be that 45 percent of the people in the Control Group exercised even though they were not given any special support related to exercise. In that case, it could be that the reason why there was little difference between the average level of depression seen in members of the Exercise Group and that seen in members of the Control Group is that there was little difference in the percentages of people in the two groups who were exercising. 

So, this choice does just what we need. It does a great job of undermining the force of the evidence provided by providing reason to believe that there wasn’t really much difference between the two groups in terms of the percentage of people in each who were exercising.

So, you can tell that, to avoid choosing trap choices when answering Critical Reasoning questions, you have to use tightly logical thinking to support your choice. If your thinking is not tightly logical, any choice that seems to go in the right direction can seem correct, and possibly even more correct than the actual correct answer, which may be written to seem irrelevant.

In order to develop the vision, attention to detail, and logical skills that you need in order to use tightly logical thinking when answering GMAT Critical Reasoning questions, be sure to do plenty of careful practice involving taking as much time as you need to answer the Critical Reasoning practice questions that you see. Rather than seek to answer questions in around two minutes each and get many incorrect, take your time, seeking to define exactly what makes incorrect choices incorrect and correct answers correct. As you develop skill, you will speed up naturally, and also, you can do timed practice later in your prep. The first order of business is to learn to see what you have to see and do what you have to do in order to arrive at correct answers consistently.