Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running toward an insect, a tiger beetle 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?
Tiger beetles are such fast runners that they can capture virtually any nonflying insect. However, when running toward an insect, a tiger beetle 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.
OG题:B前一部分:in pursing a swerving insect, a beetle alters its course while running - swering是突然转向,偏离轨道的意思。也就是说猎物一转方向,beetle就马上反应。所以失明理论就不成立(因为按照失明理论,beetle应该会反应不过来)。后一部分:its pauses become more frequent as the chase progresses. 追得越久停的次数越多,就是累了么,好理解,所以支持了休息理论。
Prep变形题:
B: the beetles usually respond immediately to changes in the insect's direction 同上理,否定掉了失明理论。但是后面一部分:pause equally frequently不能支持休息理论(更像是否定了休息理论)。个人觉得如果是往上追比往下追停得频繁就支持了休息理论。所以B不对
C:fixed time interval否定休息理论; 猎物从静态开始飞,beetles要停会才反应过来加速追,支持了失明理论
个人觉得这个C选项很难选,我应该也是做错了的。而且这种题考场上碰到一定很耗时间,还不一定对,sigh...
-- by 会员 YY_lalala (2007/4/14 20:36:00)
B Correct. This statement provides information that strengthens the second hypothesis: the swerving pursuit and the resulting continual course adjustments appear to be forcing the beetle to stop with increasing frequency to sort out the erratic visual information.
所以想请教一下,选项B削弱了哪一个,加强了哪一个?
谢谢了!
附上PREP变体的C选项。
(C) 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.
What's most interesting about this problem is how bad the OG's explanation is (for the version that's in the OG, which is not the one you're talking about).
A different version of the problem appears as #25 in the OG diagnostic chapter.
The answer key "explains" the correct answer in exactly the opposite of the actual explanation. In that problem, the correct answer supports the fatigue hypothesis and undermines the blindness hypothesis—but the "explanation" says the opposite (!!).
Ah, the joys of outsourcing answer explanations to cheaper labor (yes, this is what the OG does).
At least you can trust the problems and answers, though.
我觉得C是反对hypo1,支持hypo2。反对hypo1是因为常理是追得快则累则追击时间短,如果不管追得快还是慢,追的时间是一样的那说明pause和rest无关。而the beetle increases its speed after its next pause说明这个beetles是在停下后才加速的,说明它需要停下看清prey提速了才判断是要加速,支持hypo2。