Identify the Confounds:

1) A school psychologist hypothesizes that fear negatively influences test performance. To test this, one group of 100 students watches a video containing fear provoking images of spiders crawling on people. The other group of 100 students listens to soothing jazz music. Both groups take a test of their general knowledge.

2) Perhaps as a result of studying for tests, you have developed a cold. You call home and your mom suggests that you should eat some chicken soup (the basic kind with noodles, carrots, & chicken in broth). Your mom hypothesizes that the broth (liquid part) will make your feel better.

3) A study of therapy effectiveness on substance abuse had the experimental group undergo therapy with a general psychodynamic approach administered by Dr. Elektra, while the other group participated in therapy with a general cognitive approach administered by Dr. Ponder.

4) The human resources (HR) department of a marketing research company wants to boost the morale of the accounting department. They have decided to try two different types of messages. For employees born January-June, HR will place messages from their supervisor (e.g., "I know that we can count on you!") in the employees' paychecks. For employees born July-August, HR will put in generic jokes about accounting (e.g., "How many accountants does it take to change a light bulb? Depends, are we billing by the hour?") in the employees 'paychecks.