6) One group of participants is given water to drink while a second group is given a drink of normal (non-diet) Coca Cola. The Coca Cola group performs faster on a task of putting 20 pegs into appropriate holes. It is assumed that the caffeine in the Coca Cola has had an effect. Which of the following is a likely confounding variable?
A) The hardness or softness of the water
B) The weight of the pegs
C) Sugar in the Coca Cola
D) Colouring in the Coca Cola

Question

Quizplus · Accepted Answer

The presence of sugar in the Coca Cola may also have had an effect on performance, making it a confounding variable. It is not relevant whether the water was hard or soft or the weight or coloring of the pegs.

6) One Group of Participants Is Given Water to Drink