Imagine a study where participants were given Jell-O shots to consume before participating in experiments where reaction time was measured. However, to the participants’ surprise, the Jell-O shots were not made with alcohol. When the participants were debriefed and told that the Jell-O contained no alcohol, some participants refused to drive home until they had sobered up. The participants’ responses indicate that __________ was a threat to internal validity.

The correct answer to fill in the blank in this question: The participants´ responses indicate that ____ was a threat to internal validity, would be: Placebo effect.

Explanation:

A person´s mind, and perception, can be more powerful than reality itself. As such, if a person is convinced that something is happening, or that something is real, it will be very difficult to convince them otherwise, even in the face of fact and proof. The use of the placebo effect, counts on these principles. When a person believes that something is actually happening, like in this case believing that they were given jell-o shots, with alcohol, when in truth the shots did not have any alcohol, they will act according to what they believe. And even when they are shown that this is not the case, they are shown the truth, the mind still believes what it originally perceived as real. This is the placebo effect and it is used for several treatments, especially in addictions, and wrongful behavior, to try and "cheat" the mind and its processes. These people refused to drive, even after having been told the truth, because their minds refused to believe that the shots did not have any alcohol, as they had probably experienced before. Memory, and perception of a previous experience, led this placebo effect to take force much faster than if there had not been any.