** GLOSSARY**

ACQUISITION STAGE -- the part of a learning experiment in which a subject is acquiring a new response.

BIMODAL DISTRIBUTION -- a distribution that has two points along the score scale containing more cases than other points along the scale.

CONTROL GROUP -- a group set up with a constant independent variable to insure that changes in the dependent variable are due to changes in the independent variable.

CORRELATION -- the relationship between two sets of scores. Correlation coefficients range from -- 1 for a perfect negative relationship to + 1 for a perfect positive relationship.

DEPENDENT VARIABLE -- a variable that depends on the independent variable; the measured response in an experiment.

DISCRIMINATION LEARNING -- choosing a stimulus to which to respond based on prior differential reinforcement.

EXPERIMENTAL METHOD -- a method in which the researcher manipulates the independent variable and measures changes in the dependent variable, holding all other variables constant.

EXTINCTION -- the procedure of consistently not reinforcing a learned response, leading to a decrease in this response.

EXTROVERSION -- a personality trait characterized by sociable and outgoing behavior.

FLAT-RECTANGULAR DISTRIBUTION -- scores that are evenly distributed along the score scale.

FREQUENCY POLYGON -- a graph in which frequencies are represented by points and the points are connected by a line.

HALO EFFECT -- the influence of prior knowledge about an individual.

HAWTHORNE EFFECT -- a general improvement in performance which occurs when people receive special attention.

HYPOTHESIS -- a statement of expected results which open precedes an experiment and determines experimental design.

HYPOTHESIS MYOPIA -- a situation in which preconceived ide'as get in the way of discover,.

INDEPENDENT VARIABLE -- a variable manipulated by the experimenter.

INTELLIGENCE -- what is measured by intelligence tests.

INTERVAL SCALE -- a measurement scale that has equal intervals and no true zero.

J-CURVE -- a skewed distribution with most cases falling at the lowest values.

LATENCY OF RESPONSE -- the time interval between the onset of a stimulus and the occurrence of a response. Response latency is sometimes used to measure the course of learning.

MEAN -- a measure of central tendency; the arithmetical average.

I MEASURE OF CENTRAL TENDENCY -- a single value along the score scale that represents the center of a distribution The mean, median, and mode are the most common measures of central tendency.

MEASURE OF DISPERSION -- a value representing the spread or variability of scores within a distribution.

MEDIAN -- a measure of central tendency; the midpoint in a distribution, halfway between the lowest and the highest scores.

MODE -- a measure of central tendency; the value that occurs most ohen.

NATURALISTIC OBSERVATION -- observing and recording events.

NOMINAL SCALE -- a measurement scale used for classifying objects into groups.

NORMAL CURVE -- bell-shaped frequency come.

NULL HYPOTHESIS -- the assertion that there is no difference between groups or no experimental effect.

OPERANT LEVEL -- the base rate of response in a neutral (neither rewarding or punishing) situation.

OPERATIONAL DEFINITION -- a definition of a concept in terms of what we do when investigating the concept; e.g., motivation may be operationally defined as 23 hours of food deprivation.

ORDINAL SCALE -- a measurement scale used to classify objects in terms of order or rank.

POPULATION -- the total group from which a sample is drawn.

PSYCHOLOGY -- the science of behavior.

RANDOM SAMPLING -- a method of sampling in which all elements of the population have an equal chance of being included in the sample.

RANGE -- a measure of variation; the difference between highest and low est scores.

RATIO SCALE -- a measurement scale that has equal internals and true zero point.

RESPONSE DIFFERENTIATION LEARNING -- choosing a response or a way of responding based on prior differential reinforcement.

SAMPLE -- a subset selected from a population.

SAMPLING ERROR -- bias resulting from sampling procedures that do not provide for random selection from a population.

SELF-FULFILLING PROPHECY -- a hypothesis that becomes true because we act as though it is already true.

SKEWED DISTRIBUTION -- a distribution that is not symmetrical about its center.

STANDARD DEVIATION -- a measure of variation; the average squared deviation from the mean.

THEORY -- a set of constructs that explains several related events.

TRAIT -- a measurable and reasonably stable characteristic of personality.

TRIAL -- a unit of practice in learning experiments during which a subject encounters a specific stimulus situation.

TYPE I ERROR -- rejecting a true hypothesis.

TYPE 11 ERROR -- accepting a false hypothesis.

UNIT NORMAL CURVE (UND) -- a beli-shaped frequency curve with a mean of 0.00 and a standard deviation of 1.00.

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Unit 13 Table of Contents