A cognitive psychologist is interested in testing whether stress affects memory using laboratory rats. The psychologist placed 10 rats in a treatment group and 10 rats in a control group. All 20 rats were trained to run a maze. Next, the rats in the treatment were given weak electric shocks to induce stress while the rats in the control group were not given electric shocks. The rats were then placed in the maze, and the researchers found that the rats who were stressed by the electric shocks were unable to remember how to complete the maze while the rats in the control group were able to complete the maze.