LSAT 105 – Section 1 – Question 04

LSAT 105 - Section 1 - Question 04

February 1999

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT105 S1 Q04
+LR
Weaken +Weak
A
0%
136
B
1%
149
C
0%
149
D
99%
165
E
0%
162
121
129
137
 +Easiest 147.243 +SubsectionMedium

In an experiment testing whether hyperactivity is due to a brain abnormality, the brain activity of 25 hyperactive adults was compared to the brain activity of 25 adults who were not hyperactive. The tests revealed that the hyperactive adults had much less brain activity in the premotor cortex, a region of the brain believed to control action, than did the nonhyperactive adults. The experimenters concluded that diminished activity in the premotor cortex is one cause of hyperactivity.

Summarize Argument: Phenomenon-Hypothesis
The experimenters hypothesize that diminished activity in the premotor cortex is a cause of hyperactivity. Their evidence is a study that shows adults with significantly less brain activity in the premotor cortex were hyperactive, while those with normal activity levels were not.

Notable Assumptions
Based on a mere correlation, the experimenters assumes that less brain activity in the premotor cortex causes hyperactivity. This means they assume that the relationship isn’t the reverse (i.e., hyperactivity causing less brain activity in the premotor cortex), and also that there isn’t some other, hidden cause that’s actually responsible for both hyperactivity and less brain activity in the premotor cortex.

A
Some of the nonhyperactive adults in the study had children who suffer from hyperactivity.
Perhaps their children had less brain activity in the premotor cortex. There’s no reason to assume it’s 100% hereditary.
B
The hyperactive adults who participated in the experiment varied in the severity of their symptoms.
Even if they varied in the severity of their symptoms, they all generally had lower levels of brain activity in the premotor cortex than other participants.
C
The neuropsychologists who designed the experiment were not present when the tests were performed.
This doesn’t cast doubt on the study. There’s no reason to believe those same neuropsychologists had to be present for the experiment to be performed correctly.
D
All of the hyperactive adults in the study had been treated for hyperactivity with a medication that is known to depress activity in some regions of the brain, while none of the nonhyperactive adults had been so treated.
While there’s a correlation between premotor cortex brain activity and hyperactivity, there’s no direct causal relationship. Instead, premotor cortex brain function is diminished by a treatment for hyperactivity.
E
The test was performed only on adults because even though the method by which the test measured brain activity is harmless to adults, it does require the use of radiation, which could be harmful to children.
It doesn’t matter what’s harmful to the participants. This is especially true since, according to this answer, the participants wouldn’t have been harmed by the radiation.

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Section 1 - Logical Reasoning

Section 2 - Logical Reasoning

Section 3 - Reading Comprehension

Section 4 - Logical Reasoning

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