The Placebo Effect

       A placebo has been defined as " a substance or procedure that is objectively without specific activity for t     he condition being treated"
when patient feels improvement in health without an actual treatment, that calls Placebo Effect.
and we wonder what is actually making us feel better without any treatment but pieces of sugar pills?
the answer is our beliefs. From article- Just A Sugar Pill, we got know that every mental process is represented in the brain. A placebo can not makes you feel better unless your brain tell you so.  Therefore, while you think you are taking the right medicine, your brain already make the decision that you must feel better after the medicine, even though none of you nor your brain know it is just a sugar pill, and that is how placebo effect works.  Anyway, there are two positive placebo effect calls : 1. Inert Placebo 2.  Active Placebo .  For Inert Placebos are  those really devoid  of action, be it pharmacological, surgical... For Active Placebos are those that actually have actions, although these actions are not relevantly specific to the disease for which they are administrated.  however, there are also some issues about placebo. for example, there is a negative effect called Nocebo Effect,  when patients report that they are getting worse or that unpleasant sude-effects has occurred, Nocebe is a word derived from the Latin nocere, meaning inflicting damage. it often happens when the patients don't believe the medicine works well on them. 
nevertheless, scientists have made many experiments, afterward they found out all they are about Subject- expectancy Effect.  that occurs in experiments or medical treatment, when a research subject or patientexpects a given result and therefore unconsciously affects the outcome, or reports the expected result. Because this effect can significantly bias the results of experiments (especially on human subjects).