When a "double-blind" procedure is used in a study, it means that neither the participants nor the researchers know which condition the participants have been assigned to. For example, a RESEARCHER MAY want to find out WHETHER it is the sugar in the chocolate or just the idea that EATING chocolate makes people happy, that improves a person’s mood. One way to do this, would be to use a double-blind study in which participants were given either normal chocolate or sugar FREE chocolate and neither the researchers nor the participants will be able to tell which chocolate they had been given.

When a "double-blind" procedure is used in a study, it means that neither the participants nor the researchers know which condition the participants have been assigned to. For example, a researcher may want to find out whether it is the sugar in the chocolate or just the idea that eating chocolate makes people happy, that improves a person’s mood. One way to do this, would be to use a double-blind study in which participants were given either normal chocolate or sugar free chocolate and neither the researchers nor the participants will be able to tell which chocolate they had been given.