Question 84·Hard·Inferences
Biologist Ana Lutz observed that bumblebees flying through a tunnel painted with alternating black-and-white stripes gradually reduced their speed, stopping only when the stripes ceased. She proposed that the bees were gauging distance by counting the passing stripes. Two years later, researcher Mo Chen tested this proposal by sending bees through tunnels whose walls displayed computer animations: some tunnels showed stripes that moved in the same direction as the bees’ flight, while others showed stripes moving against it. In both cases, the bees slowed down as if they were still traversing a stationary, striped tunnel. Chen concluded that bumblebees do not tally stripes but instead estimate distance by measuring how quickly patterns sweep across their field of view.
Given Chen’s conclusion, both Lutz’s original observations and Chen’s experimental results most strongly support the inference that ______
Which choice most logically completes the text?
For inference-to-complete-text questions about experiments, (1) restate each researcher’s claim and result in your own words, then (2) treat the later researcher’s conclusion as the strongest constraint, and (3) choose the option that captures the shared takeaway without overgeneralizing. Eliminate choices that revive a mechanism the later study rules out (e.g., stripe counting) or that overfocus on one feature (e.g., direction or mere presence of a pattern) instead of the mechanism the conclusion highlights (optic flow rate).
Hints
Locate each researcher’s main claim
Identify what Lutz proposed about how bees judge distance and what Chen concluded after his experiment.
Notice what Chen’s experiment rules out
If the wall stripes themselves move on a screen, what does that suggest about whether bees are simply counting stripes versus using a more general visual-motion cue?
Focus on Chen’s stated mechanism
Chen names the kind of information bees measure: how quickly patterns sweep across their field of view. Look for an answer that paraphrases that idea.
Eliminate narrower claims that don’t match the conclusion
Be cautious of choices that (a) bring back stripe counting, (b) treat direction of motion as the key cue, or (c) say bees react to the mere presence/contrast of a pattern rather than how it moves across the visual field.
Step-by-step Explanation
Clarify what Lutz proposed
Lutz observed that in a tunnel with black-and-white stripes, bees gradually slowed down and stopped when the stripes ended. She proposed that bees gauge distance by counting the stripes they see pass by.
Understand what Chen changed and found
Chen displayed computer-animated stripes that moved either with the bees’ flight or against it. In both conditions, bees slowed as if the tunnel’s stripes were stationary. Chen concluded that bees do not tally stripes; instead, they estimate distance by how quickly patterns sweep across their field of view (optic flow).
Combine both researchers’ evidence
Taken together, the studies suggest that bees’ distance judgments depend on visual motion information from the tunnel walls. Lutz’s setup links slowing to the presence/cessation of a moving visual pattern, and Chen’s manipulation shows the key variable is the apparent motion across the eyes, not the literal number of stripes.
Match that combined idea to the answer choices
The best completion must reflect Chen’s conclusion while still fitting Lutz’s observation. The choice stating that apparent motion across the retina provides bees with information about travel distance directly matches “measuring how quickly patterns sweep across their field of view,” so it is the correct answer.