In a study of human development, investigators showed two different types of movies to groups of children. Crackers were available in a bowl, and the investigators compared the number of crackers eaten by children watching both movies. One type of movie was shown at 8 A.M. (right after the children had breakfast) and the other type of movie was shown at 11 A.M. (right before the children were to have lunch). It was found that more crackers were eaten during the movie shown at 11 A.M. than during the movie shown at 8 A.M. The investigators concluded that the different types of movies had different effects on appetite. The results cannot be trusted because:
A)the study was not double blind-neither the investigators nor the children should have been aware of which type of movie was being shown.
B)the investigators were biased-they knew beforehand what the study would show.
C)the investigators should have used several bowls, with crackers randomly placed in each.
D)the time each movie was shown is a confounding variable.

Question

Quizplus · Accepted Answer

The time each movie was shown is a confounding variable. It is possible that hunger levels could have contributed to the difference in cracker consumption, rather than the type of movie shown. If the study had controlled for the time of day that the movies were shown, then the results would have been more reliable. The other options listed may also be important considerations for future studies, but they are not as directly related to the issue of confounding variables in this particular study.

In a Study of Human Development, Investigators Showed Two Different