Question

interested in how the color of dogs irises affects human responses to dogs, akitsugu konno et al. showed images of 12 dogs faces to human participants and asked them to rate the dogs kindness and trustworthiness as well as the likelihood that they would interact with or keep the dogs. the researchers had previously adjusted the images so that each dog was presented in two versions, one with light irises and one with dark irises. they distributed the images such that no participant saw both the light and dark versions of the same dog. konno et al. found that participants responded more positively to the latter. the study’s design allowed the researchers to exclude the possibility that the results ______
which choice most logically completes the text?
a. may have been different if participants had been able to see the dogs’ irises in person instead of only seeing images that included the dogs’ irises.
b. reflected a preference on the part of participants for facial features that happened to coincide with dark irises in the dogs depicted in the images.
c. were a function of participants emphasizing the colors of the dogs’ irises over the dogs’ kindness and trustworthiness when reacting to the images.
d. could be explained by participants having preexisting positive feelings about dogs with dark irises or preexisting negative feelings about dogs with light irises.

Explanation:

The study tested how dog iris color affects human perceptions of trustworthiness, kindness, and interaction likelihood. To isolate the effect of iris color, researchers must control for confounding variables. Option B is logical because if participants’ preferences were influenced by coinciding facial features (not just iris color), the results wouldn’t reliably show the impact of iris color alone. The study’s design (presenting two versions of the same dog with only iris color changed) excludes this possibility by keeping other facial features constant.

Answer:

B. reflected a preference on the part of participants for facial features that happened to coincide with dark irises in the images.