In a study on the effects of caffeine on memory, participants drank a bottle of tasteless water containing 100, 50, or 0 milligrams of caffeine. Neither the researcher who handed out each bottle of water nor the study participants knew whether a bottle of water contained caffeine or not. This is an example of a _____ study.
A) correlational
B) case
C) single-blind
D) double-blind

Question

Quizplus · Accepted Answer

This is a double-blind study because both the researcher and the participants are unaware of which bottle of water contains caffeine. The use of a placebo (tasteless water) further supports the double-blind design.

In a Study on the Effects of Caffeine on Memory