Which indicator suggests that a research program using animals is valid?

• A. The animals are not placed in a stressful environment
• B. The animals are housed individually
• C. The animals have unlimited access to food
• D. The animals are kept in multiple enclosures

Answer: (A)

Minimizing stress is essential for valid animal research because stress triggers physiological and behavioral changes—like altered hormone levels, metabolism, immune function, and activity—that can confound study results. When animals are in a non-stressful environment, these factors stay closer to normal, so observed effects are more likely due to the experimental treatment rather than stress. That’s why the indicator that the program is valid is that the animals are not placed in a stressful environment.

The other scenarios tend to introduce confounding factors or unwanted variability: housing animals individually can increase stress in social species and isn’t a universal sign of good validity; unlimited access to food can affect metabolism and behavior; keeping animals in multiple enclosures adds environmental variation that can muddle results.