The person feels vivacity because of autohypnosis, instead of because of action of this or that invigorating drink is more often.

Such conclusions occur to experts from university of East London. For participation in experiment they have invited 88 persons which have divided into four groups. Two of them were offered real coffee, and half have told, that caffeine in it is not present. Two other groups were offered a drink without caffeine, and besides half of participants were also told that there is no caffeine in it. In 55 minutes all the participants have been suggested to pass tests. The people, assured that in their cup there is an invigorating substance, showed higher level of concentration without dependence from, whether there was in their drink a caffeine or not. Those who considered, that drinks coffee without caffeine, have shown the worst results.