Question

23.4Matching Dogs and Owners. Researchers constructed two test sheets, each sheet including 20 photos of the faces of dog-owner pairs taken at a dog-lovers field festival. The 20 sets of dog-owner pairs on the two sheets were equivalent with respect to breed, diversity of appearance, and gender of owners. On the first sheet, the dogs were matched with their owners, while on the second sheet, the dogs and owners were deliberately mismatched. Three experiments were conducted, and in all experiments, subjects were asked to “choose the set of dog-owner pairs that resemble each other, Sheet 1 or Sheet 2,” and were simply told the aim of the research was a “survey on dog-owner relationships.” In the first experiment, the original sheets were shown to subjects; in the second experiment, just the “mouth region” of the owners was blacked out in all the pictures on both sheets; while in the third experiment, just the “eye region” of the owners was blacked out. Subjects were assigned at random to the three experimental groups, and in each experiment, the number of subjects who selected the sheet with the dogs and their owners correctly matched was recorded. Experimenters were interested in whether blacking out portions of the face reduced the ability of subjects to correctly match dogs and owners.⁸ Here are the results:

Experiment	Number of Subjects	Number Correctly Matched
Experiment 1	61	49
Experiment 2 (mouth blacked out)	51	37
Experiment 3 (eyes blacked out)	60	30

1. Is there evidence that blacking out the mouth reduces a subject’s ability to choose the sheet which correctly matches the dogs and their owners? Follow the four-step process as exhibited in Examples 23.4 and 23.5.
2. Is there evidence that blacking out the eyes reduces a subject’s ability to choose the sheet which correctly matches the dogs and their owners? Follow the four-step process as exhibited in Examples 23.4 and 23.5.
3. Contrast your conclusions in parts (a) and (b) in the context of the problem using non-technical language.

Answer 1