A researcher gives a person a pill which does not really do anything, and tells them that it will make them feel better. Surveys against control groups who take no such pill, show that they do indeed feel better. Even their physiological measurements support their improved health.
Another example is where a randomly selected 50% of the students in a class were told that they were smarter and would be put in an advanced class. The other half assumes they are dumber. And indeed the "smarter" class does significantly better on test scores.
In this context, if one is told that an eastern entrance will make them feel better and perform better, and that things will go better for them, indeed they do. If someone is told that a southern entrance will bring them bad luck, their attention is on that, and it tends to come to be.
placebo \Pla*ce"bo\, n. [L., I shall please, fut. of placere to
please.]
placebo
n 1: an innocuous or inert medication; given as a pacifier or to
the control group in experiments on the efficacy of a
drug
other
2: Roman Catholic Church: vespers of the office for the dead
1. (R. C. Ch.) The first antiphon of the vespers for the dead.
2. (Med.) A prescription intended to humor or satisfy.
To sing placebo, to agree with one in his opinion; to be complaisant to. --Chaucer.