Question

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.

Hint:

When asked to evaluate competing hypotheses, look for a piece of evidence that isolates a variable. While speed impacts both fatigue and visual processing, the pattern described (faster speed forcing more stops) is better explained as hitting a processing bottleneck than as a strategy for managing physical energy.

Answer 1

Answer: (E)

Step 1: Understanding the Hypotheses
The question asks us to find a piece of evidence that helps decide between two competing explanations for why tiger beetles stop intermittently during a chase.
Hypothesis 1 (H1 - The Rest Hypothesis): The stops are necessary for physical recovery. The beetle gets tired from running at a high pace. This is an issue of physical stamina.
Hypothesis 2 (H2 - The Blindness Hypothesis): The stops are necessary for visual processing. The beetle's brain cannot process the rapidly changing visual input while running so fast, effectively making it "blind." It must stop to reacquire the target's location. This is an issue of information processing limits.

Step 2: Analyzing the Task
We need an experimental result that is predicted by one hypothesis but contradicted by the other. This will allow us to support one while undermining the other. We must evaluate each option against both hypotheses.

Step 3: Evaluating the Options
(A) The beetle running away is a new behavior not explained by either hypothesis directly. H1 (rest) offers no explanation for this. H2 (blindness) could be stretched to say the beetle stops, gets confused by the unexpected input, and flees. However, it doesn't clearly support one over the other in the context of the intermittent stopping pattern.
(B) A swerving insect is both more physically demanding (requires more changes in direction and acceleration) and visually complex. Therefore, more frequent pauses would be predicted by both hypotheses, so this result would not help differentiate between them.
(C) This option contains two claims. "Responds immediately to changes in the insect's direction" seems to undermine H2, as it suggests the beetle can process information while running. "Pauses equally frequently whether the chase is up or down an incline" undermines H1, as running uphill should be more tiring and require more rest. This option seems to weaken both hypotheses rather than supporting one and undermining the other.
(D) This describes a strategic decision to abandon a chase. It explains when a beetle might give up entirely, but not why it pauses intermittently during a successful chase. It's irrelevant to both hypotheses.
(E) This option states a direct correlation: the faster the beetle runs, the more often it stops. Let's analyze this from the perspective of both hypotheses.
Support for H2 (Blindness): This provides strong support. The faster the beetle runs, the more rapid the change in visual information. This would cause the beetle's visual processing to hit its limit more quickly and more often, thus requiring more frequent stops to "reset" and reacquire the target. The relationship is causal and direct.
Undermining H1 (Rest): This is more subtle. While it's true that running faster is more tiring, this finding undermines the rest hypothesis from a behavioral strategy standpoint. An animal managing its physical exhaustion would likely adopt a sustainable pace. The behavior described—running so fast that it forces more frequent recovery stops—is an inefficient way to manage stamina. It suggests the stops are not for recovery but are an unavoidable side effect of running fast. The speed itself causes the problem (visual blur), which fits H2 perfectly. The stops are a solution to the problem caused by speed, not a recovery from the exertion of speed. Therefore, this finding fits the visual processing limit model much better than the physical fatigue model.
Step 4: Final Answer
Option (E) provides the clearest experimental result that supports the "blindness" hypothesis while simultaneously undermining the "rest" hypothesis. The direct link between speed and stop frequency is best explained as a recurring need to process information that becomes overwhelming at high speeds.