Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running toward an insect, a tigerbeetle will intermittently stop and then, a moment later, resume its attack. Perhaps the beetles cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running, tiger beetles are unable to adequately process the resulting rapidly changing visual information and so quickly go blind and stop.

Which of the following, if discovered in experiments using artificially moved prey insects, would support one of the two hypotheses and undermine the other?

A When a prey insect is moved directly toward a beetle that has been chasing it, the beetle immediately stops and runs away without its usual intermittent stopping.
B In pursuing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses.
C In pursuing a moving insect, a beetle usually responds immediately to changes in the insect's direction, and it pauses equally frequently whether the chase is up or down an incline.
D If, when a beetle pauses, it has not gained on the insect it is pursuing, the beetle generally ends its pursuit.
E The faster a beetle pursues an insect fleeing directly away from it, the more frequently the beetle stops.



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I chose B, as it weakens the claim that they can not adequately process the rapidly changing visual info ('a beetle alters its course while running') and supports the other hypothesis - that they can not maintain their pace ('pauses become more frequent'). But the OA is C. Any insight will be appreicated.
Thanks.

Choice B should read- In pursuing a moving insect, the beetles usually respond immediately to changes in the insect's direction, and pause equally frequently whether the chase is up or down an incline.

The phrase usually respond immediately to changes in the insect's direction in choice B does not weaken the second hypothesis enough. The term usually as used leaves it open to the possibility that the tiger beetles may or may not be unable to process the resulting rapidly changing visual info., and so quickly go blind and stop. In other words, it could mean that there are times in which tiger beetles respond immediately and there are times they do not.

Choice C should read-The beetles maintain a fixed time interval between pauses, although when an insect that had been stationary begins to flee, the beetle increases its speed after its next pause.
On the other hand, Choice C strengthens the second hypothesis it reaffirms what has been stated that the tiger beetle cannot process rapidly changing visual information, since it increases it's speed after its next pause not immediately after the insect begins to flee.

ok, the first thing you have to do here is note the essence of the question. YOU MUST BE VERY, VERY LITERAL WHEN YOU READ THE QUESTION.

here's the question (emphasis mine):


note that this is TWO requirements. you have to satisfy BOTH of them.
no way around that.



this doesn't really undermine either of the two hypotheses; in fact, it's consistent with both of them.
it's consistent with the fatigue hypothesis, in that the pauses get more frequent as the chase continues.
it's also consistent with the temporary blindness hypothesis, in that more pauses are necessary if the insect is swerving (a situation that would require more frequent re-orientation due to the "blindness").

i don't see anything here that explicitly works against either of the two hypotheses.

EDIT: on reconsideration, i conclude that this choice does indeed weaken one of the two hypotheses. see below.



this is consistent with the temporary blindness hypothesis - it responds immediately once it can. it also undermines the fatigue hypothesis, because, if the fatigue hypothesis were true, the beetle would pause more often going uphill than going downhill.

Is this the same question as the one in the 11th edition orange guide (D25)?

According to OG, B is the correct answer. Even if it is a different question, why is B correct above but not here?

B In pursuing a swerving insect, a beetle alters its course while running and its pauses become more frequent as the chase progresses.

p. 83: This statement provides info that strengthens the scond hypothesis: the swerving pursuit and the resulting continual course adjustments appear to be forcing the bettle to stop with increasing frequency to sort out the erratic visual information.

Hi Ron

i am confused with C answer choice- it seems to undermine both theories - if insect can respond immi to changing directons , it shows he has no issue with visual- and he pauses equally frequently - shows that the pause has nothing to do with exertion- as correctly mentioned by you

while B seems to undermine only one theory- B says that insect can move almost immi and takes more pauses - which makes it clear that the insect pauses because of exhaustion and nt because of visual issues....

Apologies for bringing up an old question.

Option C (In pursuing a moving insect)
'a beetle usually responds immediately to changes in the insect's direction' - Undermines blindness argument because immediate response implies no pauses to overcome temp blindness
'it pauses equally frequently whether the chase is up or down an incline' - Undermines rest argument because (as you said) it must pause more for uphill chases

Option B (In pursuing a swerving insect)
'a beetle alters its course while running' - Undermines blindness argument (although not very strongly) because the beetle is able to alter while the prey flies in a swerving path.
'pauses become more frequent as the chase progresses' - Strengthens the rest argument because as the chase progresses, more fatigue will be experienced

Ron,
For option B, you said
this doesn't really undermine either of the two hypotheses; in fact, it's consistent with both of them.
it's consistent with the fatigue hypothesis, in that the pauses get more frequent as the chase continues. (Agreed)
it's also consistent with the temporary blindness hypothesis, in that more pauses are necessary if the insect is swerving (a situation that would require more frequent re-orientation due to the "blindness"). (Not sure how you reached here ? If the beetle can follow a swerving path in coordination with its prey, then doesn't it undermine the blindness theory ?)


B seems to be the best choice for me. If you still think that C is the answer can you please explain why it is so.

There were some suggestions that the OA (as per the book) is actually B. Can someone please clarify this.

ok yeah, i just looked this one up in the book. by the way, i hope that this problem is really also on GMATPREP; if it isn't, then we'll take it down.
i'm pretty sure that it is, because i cross-referenced other forums, so i think we're good.

on reconsideration, yes, (b) supports one hypothesis - the fatigue hypothesis, as mentioned above.
it also undermines the blindness hypothesis, because, unless the insect is swerving with increasing frequency as the chase progresses (something which we've no reason to assume), that hypothesis would predict that it would pause with a roughly constant frequency (whenever the swerving caused it to become disoriented).