Directions: Read the given passage carefully and answer the questions as follows:
Passage
A recent ball-catching experiment conducted in space by astronauts on board a space shuttle has led neuroscientists to conclude that the brain contains an internal model of gravity that is both powerful and persistent. At the same time, the experiment provided evidence that the brain can adapt to environments in which the force of downward acceleration is less pronounced than it is on earth.
The experiment’s outcomes suggested that an individual’s understanding of motion is hard-wired from an earthcentric perspective. In the experiment, the astronauts were asked to catch balls released from a spring-loaded cannon.
Analyzing data gathered from infrared tracking cameras and electrodes placed on the astronauts’ arms, McIntyre, the experiment’s principal designer, noticed that the astronauts’ anticipation of the ball’s motion was slightly off. Though they were able to catch the ball, the astronauts expected the ball to move faster than it did. He theorized that this over-anticipation is due to the fact that the brain expects the force of the earth’s gravity to act on the ball.
The experiment also demonstrates the brain’s ability to adjust to conditions that run counter to its pre-set wiring.
While the astronauts did not adapt to the conditions in space for some time, by day 15 of the experiment, the amplitude of the premature arm movements decreased and a new well-timed arm movement immediately preceded the catch. Upon returning to earth, the astronauts again mis-anticipated the ball’s motion, though this time the ball moved faster than anticipated. However, the astronauts were able to adjust back to the earth’s gravitational effect on the balls much more quickly than they had been able to adapt to the conditions in space.
Many scientists view the findings as a first step in research that could have serious practical benefits. The ability of astronauts to safely explore space and investigate other planets is dependent on understanding the differences between our physical reactions on earth and elsewhere.
On another level, understanding timing processes in the body might lead to the development of treatments for coordination problems experienced by individuals with certain types of brain damage.
Question for Practice Test: Reading Comprehension - 6
Try yourself:Which of the following, if true, would support McIntyre’s theory that the brain has built-in knowledge of gravity?
Explanation
McIntyre's theory, as explained in the passage, is that the brain contains a powerful and persistent internal model of gravity, built from an earth-centric perspective. The astronauts' misjudgment of ball motion in space (expecting it to move faster due to Earth's gravity) shows that their brains were hard-wired to assume Earth’s gravity, even when it was no longer present.
Option c supports this theory because:
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Disorientation in space during the early days implies that the brain is pre-wired to function under Earth's gravity.
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This aligns with the idea that the brain's model of motion is built assuming Earth’s gravitational force — and it takes time to override or adjust that internal model when gravity changes.
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Question for Practice Test: Reading Comprehension - 6
Try yourself:The function of the final paragraph is to
Explanation
The earlier paragraphs of the passage have a narrow focus in that they are chiefly concerned with a specific description and interpretation of the ballcatching experiment. The final paragraph opens up this focus by commenting on the broader implications of the experiment, such as the practical benefits this new understanding might have on safe space travel and on potential treatment for certain coordination problems.
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Question for Practice Test: Reading Comprehension - 6
Try yourself:According to the passage, research suggests that the brain’s built-in understanding of gravity is
Explanation
One of the major outcomes of the experiment described in the passage is that "the brain can adapt to environments in which the force of downward acceleration is less pronounced than it is on earth."
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Question for Practice Test: Reading Comprehension - 6
Try yourself:It can be inferred from the passage that during the first two weeks of the experiment the astronauts, in attempting to catch the ball, tended to
Explanation
The astronauts moved their arms prematurely during the first two weeks of the experiment. This means that they adjusted their arms sooner than was necessary to catch the ball.
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Question for Practice Test: Reading Comprehension - 6
Try yourself:The passage implies which of the following about gravity?
Explanation
The opening paragraph uses the phrase “less pronounced” to describe the difference in gravitational conditions in space and on earth. Moreover, the passage states that astronauts had “premature arm movements” when attempting to catch balls in space, implying to researchers that the astronauts were faced with a weaker downward acceleration in space than they had anticipated based on their brains' earth-centric wiring.
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Question for Practice Test: Reading Comprehension - 6
Try yourself:The primary purpose of the passage is to:
Explanation
This choice directly relates to the first paragraph, which presents the experiment's conclusions, and to the second and third paragraphs, which describe the experiment in-depth.
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