Researchers are studying the relationship between depression, self esteem and optimism in adolescents thought to be at risk. They gave 200 children three well know instruments in which likert responses are averaged to give a standard score. A sport psychologist designs a study to determine if cross-country runners can enhance their performance using mental imagery techniques. He first measures everyone s imagery ability and then categorizes them into a high and low imagery group based on their scores. He then provides half of the subjects in each group with imagery based mental rehearsal training.
All runners continue with their normal physical training schedule.
One month later he measures each runner s time to complete the cross-country course and subtracts it from their pretaining score to get a measure of improvement.