What is a control group in psychology?

A control group is usually used in experimental psychology to study the effect of an intervention or treatment. Research in psychology covers a number of topics. Sometimes, in order to verify whether an effect is significant, it is necessary to compare two groups or more. One of these groups will be a control group. A control group will often present the same characteristics as the other groups but will not be exposed to treatment or intervention, contrary to its counterpart(s). For example, group A can receive a newly developed therapy for depression, whereas the control group will not receive this therapy. Later on, both depressed groups will be compared to determine if the therapy had a significant effect, or, in other Words, if it worked. Another example pertains to social therapy. A researcher could study the effect of setting short terms realistic goals on attaining long term goals. As such, a group of students would receive help on how to set short term goals, how to reach them, how to deal with obstacles, etc to attain long term goals. The control group, also made of students, would not receive such an intervention and would be told to set up long term goals and try to achieve them. At the end of the research period, both groups would be compared to see whether the intervention in helping setting short term goals and achieving them made a difference in term of goal achievement.