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?
Explanation
Context: Konno et al. showed participants dog images with artificially lightened or darkened irises. Participants rated dogs with dark irises more positively. But no participant saw both versions of the same dog — so participants didn't know irises were manipulated. The blank states what an alternative explanation might be for the dark-iris preference finding.
Answer: 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.
Why? Since participants saw only one version of each dog and never compared light vs. dark for the same animal, their ratings could reflect preferences for other features (like face shape or expression) that correlated with which dogs were assigned dark irises in the study. B states this confounding-feature explanation.
Traps:
- A) may have been different if participants had been able to see the dogs' full bodies → about visibility scope, not a methodological alternative explanation for the iris-preference finding
- C) were a function of participants emphasizing iris color specifically → this would support the iris-preference finding, not offer an alternative explanation
- D) could be explained by participants having preexisting positive feelings toward certain breeds → about breed preference, which the study's design (adjusting the same dog images) should have controlled for