Question

Difficulty: Very hardSingle-Sentence Inferences

Consider the following excerpt from a monograph on cognitive neurobiology:

"While early twentieth-century neurobiologists posited that human speech perception relies exclusively on auditory cortex processing of acoustic frequencies, recent neuroimaging reveals that motor cortex activation occurs synchronously during phoneme recognition—not as a secondary reflective response, but as an integral component required to parse ambiguous acoustic inputs under noisy ambient conditions."

Statement: Based on the excerpt, it can be validly inferred that motor cortex activation during phoneme recognition is entirely absent when acoustic inputs are unambiguous and ambient noise is absent.

Answer: Answer

Answer

The statement is False. The target sentence indicates that motor cortex activation is necessary for parsing ambiguous acoustic inputs in noisy conditions, but it makes no claim regarding whether motor cortex activation is present or absent under quiet or clear conditions.
The statement is false because GMAT reading comprehension inference questions demand strict logical deduction. The source sentence establishes that motor cortex activation is an essential component for parsing ambiguous inputs in noisy environments; however, it nowhere asserts or implies that motor activation disappears in noise-free environments. Assuming the negation of a condition's outcome when the condition is removed is a classic unwarranted extrapolation trap.

Step-by-Step Solution

1
Analyze the scope of the target sentence
The sentence identifies recent findings showing that motor cortex activation occurs synchronously during phoneme recognition and is required to parse ambiguous acoustic inputs in noisy ambient conditions.
Establishing the precise claims made by the author is essential to avoid reading unstated assumptions into the text.
2
Evaluate the proposed inference against the text
The proposed statement claims that motor cortex activation is 'entirely absent' when inputs are unambiguous and ambient noise is absent.
Testing whether the text strictly guarantees this claim or merely describes what happens in noisy conditions.
3
Identify logical boundaries and traps
Stating that a mechanism is required in Condition X does not imply that the mechanism is completely inactive in the absence of Condition X. Doing so constitutes an unwarranted extrapolation.
GMAT single-sentence inferences strictly require conclusions that must be true based solely on the text provided without additional speculative leaps.

Key Concept

Single-Sentence Inferences and Avoiding Unwarranted Extrapolation
Estimated Time:2m 0s
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