Psychology Dictionary -- M


Characteristic of a scale of measurement where the individual units possess the qualities of greater than, equal to, or less than.

Main Effect

The effect of one variable on another without any other variables or subgroups involvement.

Manifest Content

According to Freud, the story-like superficial content of a dream, often representing only the daily activities and little underlying unconscious material.

Maslow, Abraham

Humanistic Theorist most famous for the development of the Hierarchy of Needs.


Changes due to the natural process of aging as determined by your genetics


A measure of central tendency determined by adding all scores together and dividing by the number of scores. Often referred to as the statistical average.

Measure of Central Tendency

An average (see Mean, Median, and/or Mode)

Measurement, Scales of

Categories of data based on their numerical characteristics (See Ratio, Interval, Ordinal, and Nominal Scales)


A measure of central tendency that uses the middle most occurring score in a distribution (the score that occurs at exactly the 50th percentile).

Medulla Oblongata

Part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion.

Memory Effect

Error in research that results from subjects recalling previous testing and applying that knowledge to current testing.


A curve or distribution that has a balanced amount of variance so that is resembles a normal curve.

Meta Analysis

The statistical procedure used to combine numerous and independent research results into one study. Each research study becomes one subject in the meta-analysis.

Minnesota Multiphasic Personality Inventory, 2nd. Edition

An Objective test utilizing 567 items which have been empirically derived to measure a variety of psychological concerns.


See Minnesota Multiphasic Personality Inventory, 2nd. Edition.


A measure of central tendency that uses the most frequently occurring score. A distribution with two or more scores that are equal and occur most frequently is called multi-modal.


Learning through the imitation or observation of others.


Subject drop-out in a research study. Mortality becomes a problem when a disproportionate drop out rate occurs between two or more groups (Example: 30% of males drop out of group one while only 2% of males drop out in group two, resulting in uneven groups).


The process that energizes and/or maintains a behavior.


Internal states that provide direction for one’s behaviors.

Multiple Correlation

A correlational technique used when there is one X and two or more Y. (Example: the correlation between age and (math and English ability).