Final answer:
A pillbug shows a preference for a test substance in a choice chamber if it spends more time in the chamber with the substance, demonstrating a positive behavioral response to the stimulus.
Step-by-step explanation:
Pillbug spends more time in chamber with test substance:
When pillbugs are placed in a choice chamber, the behavior that indicates a preference for the test substance is pillbug spends more time in chamber with test substance. This observation aligns with principles of animal behavior and response to stimuli, where organisms tend to stay longer at places that they find favorable or beneficial. For instance, in experiments where animals are given a choice between two environments, scientists can infer preference based on where the animal spends most of its time.
These principles are similar to observed behaviors in other species, such as the salamander experiments or studies conducted on predatory birds and butterflies. In these investigations, preference and avoidance can shape natural selection by influencing traits that help an individual avoid predators or find resources more effectively. This could be observed through positive responses such as moving toward a favorable condition, or negative responses like moving away from an unfavorable one.