Reading ComprehensionDifficulty: Medium

PT148 S2 P4 Q24 Explanation

Brain Scans

A free, expert breakdown of this official LSAT Reading Comprehension question.

TopicsLocal PurposeScience

Keep going in LSAT Lab

  • Save & drill this skill — build targeted practice sets from questions like this one

  • Video walkthroughs — watch every question solved step by step

  • 81 official LSATs — as questions, timed sections & full-length tests

Start practicing free

Free to start

Full official LSAT questions are available through LawHub. This page provides LSAT Lab's explanation, strategy, and review tools without republishing the full official question.

Passage

There are some basic conceptual problems hovering about the widespread use of brain scans as pictures of mental activity. As applied to medical diagnosis (for example, in diagnosing a brain tumor), a brain scan is similar in principle to an X-ray: it is a way of seeing inside the body. Its value are instantiated in localized brain regions. This premise is known as the modular theory of mind.

It may in fact be that neither mental activity, nor the physical processes that constitute it, are decomposable into independent modules. Psychologist William Uttal contends that rather than distinct entities, the various mental processes are likely to be properties of a more general mental activity that is distributed throughout the brain. It so for a reason. To cleanly separate emotion from reason-giving makes a hash of human experience.

But if this critique of the modular theory of mind is valid, how can one account for the fact that brain scans do, in fact, reveal well-defined areas that “light up” in response to various cognitive tasks? In the case of functional magnetic resonance imaging (fMRI), what you are seeing when you remains after the subtraction represents the metabolic activity associated solely with the cognitive task in question.

One immediately obvious (but usually unremarked) problem is that this method obscures the fact that the entire brain is active in both conditions. A false impression of neat functional localization is given by differential brain scans that subtract out all the distributed brain functions. This subtractive method produces striking images of the it is illustrated so well by the products of the subtractive method?

What this question is testing

Local Purpose

Your task

Identify why the author included the referenced detail at that point in the passage — its function, not its content.

Common trap

Answers that merely repeat or summarize the topic of the detail instead of describing the role it plays.

Winning move

Ask what job the detail does for the paragraph, then for the passage's broader point.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
24.

The author draws an analogy between brain scans and X-rays primarily in

Answer choices

  1. Correct71% picked this

    contrast a valid use of brain scans with one of more

    Why this is right

    The author is saying, "The use of brain scans in medical diagnoses is a valid use (it's similar to X-rays). However, the use of brain scans in psychology is a fundamentally different kind of enterprise (i.e. one of more doubtful value)." We would like that "valid use" reinforces "its value is straightforward and indubitable" and that "contrast with one of more doubtful value" matches up with "However, this other use is a different kind of thing."

    Skill tested: Local Purpose · how this choice captures the passage's function is the move to repeat next time.

  2. Out of Scope: popularity of theory6% picked this

    suggest that new technology can influence the popularity of a

    There hasn't been any theory yet discussed in the passage, so there's no way that at this moment in the text the author is making a point about how new tech can influence the popularity of a theory. Can we even connect this idea to X-rays? When X-rays were a new technology, did they influence the popularity of some scientific theory?

  3. Out of Scope: less precise8% picked this

    point to evidence that brain scans are less precise than other

    Nothing in this paragraph compares the precision of a brain scan to the precision of any other technology. The author never said that X-rays are more precise than brain scans. She seems to place them on equal footing. They are both ways of seeing inside the body, whose value are straightforward and indubitable.

  4. Out of Scope: undermine a theory8% picked this

    argue that X-ray images undermine a theory that brain scans are often

    There hasn't been any theory yet discussed in the passage, so there's no way that at this moment in the text the author is saying that brain scans are used to support a theory, while X-ray images could be used to undermine the same theory.

  5. Out of Scope: evolved from7% picked this

    show how brain scan technology evolved from older technologies such

    There's nothing in the text suggesting that brain scan technology is some outgrowth or evolution of X-ray technology. The author is merely saying that both technologies have obvious value, as a way of seeing inside the body.

Continue the review in LSAT Lab

Save this question, watch the video walkthrough, and drill similar questions in your LSAT Lab account.

Save and practice this skill
LSAT Lab

Turn this review into a targeted study plan.

Save this question, drill more like it, watch the video walkthrough, and track your progress in your LSAT Lab account.

Start practicing free