Correlations and Causations

1. Correlations and Causations • Dr. Sarah N. Dipety conducted an experiment to see whether chocolate can improve memory better than plain sugar can improve memory. To recruit participants, Dr. Dipety put the following ad in the local newspaper, “Earn $20 for participating in a one-week study on eating habits. Call Dr. Dipety at the Department of Psychology.” Forty people answered the ad and came to Dr. Dipety’s lab, where they were given 35 candies to eat during the week. Participants were told to swallow, not chew, each candy with a glass of water every three hours (i.e., five candies per day). All candies were coated with a tasteless shell that would dissolve in the stomach. Inside this shell, some candies were filled with chocolate, others with plain sugar. The first twenty participants that phoned Dr. Dipety were given candies filled with chocolate; the second twenty participants were given candies filled with plain sugar. Participants did not know which candies they were receiving. After the participants finished their one-week study, they went to Dr. Dipety’s office. At that time, each person was given a memory test about items they might have seen in Dr. Dipety’s lab during the previous visit. The results of the study showed that people who swallowed the chocolate candies remembered the items in Dr. Dipety’s lab more often than the people who swallowed the plain sugar candies.

2. Instructions: • In this experiment, identify examples of the following: independent variable, dependent variable, experimental group, control group, placebo, nonrandom sampling (sampling error), and nonrandom group assignment.