Reading ComprehensionDifficulty: Medium

PT148 S2 P4 Q20 Explanation

Brain Scans

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

TopicsMain PointScience

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

Main Point

Your task

Capture the passage's overall primary point — the claim everything else supports.

Common trap

Answers that are true but too narrow (a single paragraph) or too broad (beyond the passage's scope).

Winning move

Summarize the whole passage in one sentence first, then match it to a choice.

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

The question
20.

Which one of the following most accurately states the main point of

Answer choices

  1. Wrong Emphasis Unsupported: grown rapidly3% picked this

    In spite of troubling conceptual problems surrounding brain scan technology, its use in psychological research on mental

    The main clause here is that "the use of brain scans in psychological research has grown rapidly". Would that be the one idea the author would prioritize us hearing? We were looking more for something like, "Brain scans are misleading, so they're weak support for the modular theory of the mind". While the warm-up clause here alludes to those concerns, the main clause seems like a neutral report on a growing trend. Even worse, there's no support in the passage that the brain scan usage has "grown rapidly".

  2. Correct81% picked this

    The use of brain scans to depict mental activity relies on both a questionable premise

    Why this is right

    This correctly centers the main point on the author's Challenge Position vibe. She's not a fan of the modular theory of mind (as the 2nd paragraph reveals). So that's the questionable premise underpinning the use of brain scans to depict mental activity. And the author thinks that the subtractive method of fMRI scans is a misleading methodology: it gives off the false impression of neat localization.

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

  3. Wrong Emphasis: lacks main topics1% picked this

    Contrary to what is usually asserted in the popular press, reason and emotion are probably not located in the prefrontal

    This answer fails to mention or allude to brain scans or the modular theory of the mind, the two main topics of the passage.

  4. Wrong Objection2% picked this

    Although the fMRI is usually interpreted as a measure of metabolic activity in the brain, this interpretation is misguided and

    The author is never saying (as this answer is) that fMRI's do not measure metabolic activity. She's just saying that by only showing the differential in metabolic activity, the scans give off the false impression that only some parts of the brain are active, when in fact the entire brain is still metabolically active.

  5. Lacks Author's Opinion13% picked this

    The modular theory of mind has gained wide currency precisely because it is illustrated effectively by the images

    While this deals with the main topics (and sounds a ton like the final sentence), this is just a descriptive statement of causality. If you just read this sentence (and not the passage), you'd have no idea if the modular theory of mind is right or wrong. You'd have no idea if the author believes in the modular theory of mind; you'd have no idea if she has any issues with the subtractive method. So this answer fails to capture any of the Challenge Position sentiment of the author. To fix this answer, we need something like, "Although it seems counterintuitive, the modular theory has gained popularity because it is illustrated effectively by the misleading images produced by the subtractive method".

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