The use of lie detectors is based on the assumption


The use of lie detectors is based on the assumption that lying produces emotional reactions in an individual that, in turn, create unconscious physiological responses.

Option A
Option B
Option C
Option D
Option E

(This question is from Official Guide. Therefore, because of copyrights, the complete question cannot be copied here. The question can be accessed at GMAT Club)


Sentence Analysis

The sentence says that the use of lie detectors is based on some assumption. The assumption is that lying produces emotional reactions in an individual and that these emotional reactions, in turn, produce unconscious physiological responses.

The important aspect here is understanding the meaning of the sentence. Some students assume that in “that, in turn, create..”, ‘that’ refers to individual. The cause of this wrong assumption is that the student is not paying attention to the meaning of the sentence. Once you pay attention to the meaning of the sentence, you’ll understand that an individual cannot logically create physiological responses. This understanding will raise a question: “Then, what is creating these responses?”. The answer is “emotional reactions”.

Now, the question is: “Can ‘that’ refer to emotional reactions?”. The answer is Yes. Noun modifiers can jump over other essential noun modifiers and, in some cases, over other verb modifiers as well. So, ‘that’ can jump over “in an individual”, a prepositional modifier modifying the verb ‘produces’, to modify ‘emotional reactions’.

Once you understand that ‘that’ refers to ‘emotional reactions’ and not ‘individual’, you’ll realize that we need a plural verb ‘create’.

The given sentence, thus, has no logical or grammar errors.

Option Analysis

(A) Correct.

(B) Incorrect. Incorrect. For the below reasons:

  1. Singular verb “creates” doesn’t go with plural subject “emotional reactions”.
  2. Also, preferably, the placement of “in turn” should be closer to the verb that it is modifying. Placing it at the end makes understanding the meaning a bit difficult.

(C) Incorrect. ‘creating’ is a verb-ing or present participle modifier. Since it occurs without a coma here, it can modify ‘individual’ or ‘emotional reactions’. Logically, it is clear that it should modify ‘emotional reactions’. So, as far as the modification goes, I don’t think there’s any problem. Then, why is this choice wrong?

As you can see, the only difference between the correct choice ‘A’ and this choice is that in this choice ‘that create’ (a relative clause) has been replaced by ‘creating’ (present participle). In general, they can replace each other to modify nouns. However, in some case, they cannot replace each other. The present sentence is one of those cases.

For example:

  1. The girl who fell from the stairs broke her leg.
  2. The girl falling from the stairs broke her leg.
  3. The person who broke the glass was punished later.
  4. The person breaking the glass was punished later.

In the above sentences, as you may ‘feel’, sentences 2 and 4 don’t feel right. If you feel so, your feeling is correct. While sentences 1 and 3 are perfectly fine, sentences 2 and 4 are not. The reason is that when we are talking about a single completed event, we need to use the relative clause instead of a present participle.

Similarly, one cannot replace below sentences with each other; they have different meanings.

  1. A man who drives on the footpath is crazy
  2. A man driving on the footpath is crazy.

The first sentence lays out a general rule that anyone who drives on the footpath is crazy while the second sentence seems to talk about a specific man driving on the footpath currently.

Thus, we cannot always replace a relative clause with a present participle. Let’s look at the simplified version of the sentence with option A and option C:

  1. lying produces emotional reactions that, in turn, create physiological responses.
  2. lying produces emotional reactions creating, in turn, physiological responses.

While the first version communicates clearly the sequence of events (First – lying produces emotional reactions. Second – emotional reactions create physiological responses), the second version seems to indicate the lying produces emotional reactions that are creating physiological responses from the get-go. The sequence of events is thus distorted in the second version. Therefore, option C is incorrect.

(D) Incorrect. For the following reasons:

  1. The use of infinitive “to create” indicates that lying produces emotional reactions with a purpose to create physiological responses. Clearly, this meaning is illogical since lying cannot have a purpose to achieve something!
  2. Also, it is obviously overly wordy to write “physiological responses that are unconscious” rather than “unconscious physiological responses”.

(E) Incorrect. For the following reasons:

  1. “who” can only refer to people, not things or ideas. Thus, as is, “who” refers to individual in this option. Thus, it seems to indicate that individuals create unconscious physiological responses. Clearly illogical.
  2. Also, as explained in option B, the placement of “in turn” closer to verb “creates” is preferred.

About Chiranjeev Singh

An Alumnus of IIM Ahmedabad and with a score of 780 (2017) and 770 (2013) on GMAT and 99.98%ile on CAT, Chiranjeev is one of the most qualified GMAT tutors in India. Chiranjeev has earlier served as Director of Curriculum at e-GMAT. Chiranjeev has been helping students ace GMAT since 2012. He follows a concept-based methodology to teaching GMAT and is very committed to student success. You may contact him for any private GMAT tutoring needs at +91 9971 0010 67 or He conducts online sessions for students across the world.

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