A scientific study provides evidence that crows are capable of recognizing threatening people and can even pass their...

Ryan-Mahabir on September 12, 2019

Why is A correct? Why is B incorrect?


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Skylar on September 13, 2019

@Ryan-Mahabir Happy to help.

Let's begin by breaking down the argument. The claim is that "crows are capable of recognizing threatening people and can even pass their concerns on to other crows." The evidence offered in support of this claim is an experiment researchers did where they wore masks while trapping and releasing crows in the same area. Years later, people in the same masks returned to the area and were shrieked at and dive-bombed by crows. When reading this, we should note that we do not know which crows attacked the people - was it the same group of crows that had been trapped or was it made up of at least a few different crows in the same area? This is helpful to keep in mind while we evaluate the answer choices.

Answer A is the correct answer because, when negated, it makes the argument fall apart. Consider this negation- "none of the crows that shrieked at and dive-bombed people wearing the masks were not among the crows that had been trapped" (or, for the sake of avoiding the double negative - all of the crows that shrieked and dive-bombed were part of the group that had been trapped). This means that the crows likely remembered the masks and proceeded to attack because of this memory. It does not in any way support the claim that the crows can recognize new threatening people nor that they "can pass on their concerns to others."

Answer choice B is incorrect because it does not address the claim/does not bridge the gap between the experiment and the study's conclusion. Also, when negated to "crows that perceive an individual as threatening DO NOT ALWAYS respond by shrieking and dive-bombing," it does not significantly change the argument.

I hope this helps to clarify. Please let us know if you have any additional questions!

tomgbean on December 24, 2019

Skylar, the passage does not say that crows can recognize "new threatening people." It simply says crows can recognize threatening people. I understand the negation of A states that crows cannot pass on info to other crows about threatening people but I was willing to overlook this because the negation of E...that crows cannot distinguish between people wearing caveman masks and those who are not seems to destroy the argument...the second part of answer E I took to be inconsequential. So I think I understand why E is wrong....but just wanted to make sure about the understanding of B. Does irrelevant information at the end of an otherwise good answer choice always makes the answer choice wrong? or does the end part of E means that crows can only recognize people in masks so that crows cannot recognize threatening people who are not wearing masks? Also, does the crow have to have experienced a threatening situation with the threatening people?...the passage seems to suggest this.

inaecavalcante on July 25 at 01:35AM

I have the same question as above!

Emil-Kunkin on July 30 at 10:41PM

E is really tough to knock out by negation. This is why I prefer to treat necessary assumption questions a must be trues. We don't know that all of E has to be true to the author. While she would agree with the first, half, we have no idea about her position on the second half. So, e on the whole doesn't have to be true to the author.