Mean is not a measure of variability - it is a measure of central tendency, along with mode and median. Measures of variability show the spread of a data set and describe how different points are from one another, whereas measures of central tendency are representative of the data set as a whole.

The Hawthorne effect is also known as "the observer effect." Subjects of a study will alter their behavior if they are aware they are being observed. Because the researcher was watching the experiment, it is possible that the subject behaved differently than he would have if he was not being watched.

Jessica's z-score indicates how many standard deviations below or above the mean Jessica's test score was. Jessica's test score of 70 was less than the mean (95), so we know that the the answer must be negative.

We know that the standard deviation was , so

Jessica's z-score is 

A PET scan measures chemical activity in the brain.

An EEG measures brain activity by detecting waves and is typically used in sleep studies.

A CAT scan uses x-rays to take images of the brain and can be useful when looking at the brain's physical structure.

An MRI also can be used to examine the structure of the brain, but uses magnetic resonance to produce images.

Introspection is when a person uses their personal experience to look inward. Wundt believed that a focused practice of introspection could be used to find and study the basic elements of the human mind. Wundt's practice of introspection fell out of favor by the 1930s, and his primary contribution to the history of science was his founding of the first experimental psychology lab, which helped formalize the study of psychology as an academic disciple.

Functionalism, while it never became a formalized school of psychological thought, had an important impact on the field. Functionalism considered thinking and behavior in terms of functional adaptation to the subject's environment. It is fallacious to say that a school of thought must have been formalized and maintained in order to have influence in a field of study.

Falsifiability is the principle that states that a research hypothesis must be able to be disproven. This does not mean that the hypothesis needs to be disproven in the study; however, hypothesis should be able to be disproven. If a hypothesis is correct under all conditions, then there is no way to scientifically test its validity.

The dependent variable is what the researchers measure in the experiment. In this case, the dependent variable is reactions of the participants to the drug or placebo (the independent variable). Since the reaction depends on the drug and is not within the direct control of the researchers it is the dependent variable.

The independent variable is what the researchers manipulate in the experiment. In this example, since the distribution of the drug and placebo is the element controlled by the researchers, it is the independent variable.

The population is the entire group of people that the researcher is interested in, and the sample is the (often much smaller) group of people from that the researcher collects information from. Sampling is the process by which the sample group is chosen from the population.