Scientists found that sleeping considerably improves our creativity. After taking a nap people are able to think faster and put more imagination into their thinking. Besides, if we dream, the thinking abilities are improved even more. Researchers consider that sleeping on a problem in most cases leads to elucidation . They say when a person enters a phase called Rapid Eye Movement (REM) during sleep, _ increases the effect. Such phase takes place right before we awake and according to scientists it helps our brain make links between unrelated subjects. In the study, led by Professor Sara Mednick, scientists made a conclusion that the REM was "important for assimilating  new information into past experience" in order to find solutions to creative problems. Prof. Mednick is a psychiatrist at the University of California. Her study involved the analysis of 77 adults. Each participant was given several word-associated creative tasks. All tasks were given in the morning, with participants being shown a number of groups of 3 words, for example: cookie, heart and sixteen. They were asked to come up with a word that would be associated with all three given terms--like sweet. Sometime later, after some participants were allowed to sleep, they were asked to perform the same tasks and some new ones. It is worth mentioning that while some people slept, researchers used brain scans to see the type of sleep each participant entered. When given the same tasks, participants, who took a nap, were able to give more varied solutions, some of which were much better than they gave earlier. But when given new tasks, researchers found that those who entered REM sleep had a 40 percent better result compared to the performance they showed in the morning. The important stage in the study is  _  .
to think of a creative word to show a group of 3 words to give participants time to think to let some participants sleep for a while