It's not every day you get to see a three-way interaction described in the news! But here's one, a study covered by the Huffington Post.
The headline was as follows:
Extroverted Children More Likely To Be Swayed By Environmental Cues: Study
Read this study description and identify the three independent variables in the design. Identify the dependent variable, too.
The study...included 18 kids ages 6 to 10, whose levels of introversion and extroversion were rated on a scale by teachers and counselors.
On one day, the kids were served breakfast by adults; they were given a large [or a small] bowl, and then told the adults how much cereal and milk they wanted to have. On another day, the kids served themselves breakfast [after being given a large or small bowl]. The amount of food served -- whether by the adults, or the kids themselves -- was secretly weighed by scales hidden in the tables.
a) What are the three IV's and the DV in this study?
b) Try graphing the result. Here's your hint: you'll have two graphs: one for kids being served by adults, and the other for kids serving themselves. Each graph will have the other two IV's on it. Use this description of results to estimate the pattern:
Extroverted kids served themselves 33.1 percent more breakfast when they had the larger bowl, compared with introverted kids, who only served themselves 5.6 percent more when they had a larger bowl.
When the adults were serving for them, both extroverted and introverted kids asked for more than 50 percent more when they had a bigger bowl.
Suggested answers
a) The three IVs are:
Personality type: Extroversion/introversion (this is actually a participant variable, not a true IV). This was between subjects.
Bowl size: Large or small, between subjects.
Server: Self or adult, between subjects.
b) You can check your graph against the 2x2x2 bar graph in the original paper. Click here, and scroll to Figure 1.