One theory suggests that yawning is triggered by increased levels of carbon dioxide in the blood, but other studies have contradicted this.

However, one Air Force commissioned study contradicted some of these contentions.

But, he said, the new study contradicts that theory.

The study, which generally agreed with previous research on the topic, contradicted some beliefs about family violence.

Not a single report or study contradicts the correlation between race and overassessment.

However, a new study is contradicting that finding.

Numerous studies contradict each other concerning even the most obvious dates.

Their study contradicts one published only a few weeks ago, using the same dataset, that showed no link between the drugs and the disease.

The study contradicts previous papers which claim that sleeping helps us take the edge off negative emotions and view them from a more rational perspective.

The study, the researchers said, contradicts the argument made by many doctors that the samples do not influence them.