Question

Tiger beetles are such fast runners that they can capture virtually any running insect. However, when running toward an insect, a tiger beetle will intermittently stop and, when 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.

Hint:

When evaluating hypotheses based on behavior, consider how changes in conditions (such as speed) directly affect the behavior.

Answer 1

Answer: (E)

Step 1: Understanding the two hypotheses.
The first hypothesis suggests that beetles pause because they need rest, while the second suggests that they cannot process the visual information effectively. The latter would predict that as the beetle runs faster, the frequency of stopping would increase.
Step 2: Analyzing the options.
- (A) This would support the first hypothesis but not the second, as it suggests the beetle stops for a rest when the prey moves directly toward it.
- (B) This does not address the idea of running speed affecting stopping frequency, and would not help either hypothesis.
- (C) This demonstrates that the beetle is responsive to the insect’s direction, but does not speak to the frequency of stopping in relation to speed.
- (D) This offers insight into the beetle’s pursuit behavior, but it does not address how running speed affects stopping frequency.
- (E) This supports the second hypothesis, as it shows that faster speeds lead to more frequent pauses, consistent with the idea that the beetles are overwhelmed by the rapid visual changes.
Step 3: Conclusion.
The correct answer is (E), as it supports the second hypothesis and undermines the first.