Modules 5-8: Theoretical Perspectives on Psychology

Scientific Method

A series of steps followed to solve problems including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions.

hindsight bias

the tendency to believe, after learning an outcome, that one would have foreseen it

hypothesis

A testable prediction, often implied by a theory

control group

In an experiment, the group that is not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.

experimental group

In an experiment, the group that is exposed to the treatment, that is, to one version of the independent variable.

operational definition

a carefully worded statement of the exact procedures used in a research study

independent variable

in an experiment, the factor that is manipulated; the variable whose effect is being studied

dependent variable

in an experiment, the outcome that is measured; the variable that may change when the independent variable is manipulated

experimenter bias

a phenomenon that occurs when a researcher's expectations or preferences about the outcome of a study influence the results obtained

double-blind procedure

an experimental procedure in which both the research participants and the research staff are ignorant about whether the research participants have received the treatment or a placebo. Commonly used in drug-evaluation studies.

confounding variable

a factor other than the factor being studied that might influence a study's results

sampling

The process of selecting representative units from a total population

random assignment

assigning participants to experimental and control conditions by chance, thus minimizing preexisting differences between those assigned to the different groups

stratified sampling

A type of probability sampling in which the population is divided into groups with a common attribute and a random sample is chosen within each group

representative sample

A sample that reflects the characteristics of the population from which it is drawn

sampling bias

a flawed sampling process that produces an unrepresentative sample

conformity effect

the pressure we feel to conform to the behaviors and beliefs of groups in which we find ourselves

survey

a descriptive technique for obtaining the self-reported attitudes or behaviors of a particular group, usually by questioning a representative, random sample of the group

naturalistic observation

a descriptive technique of observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation

case study

a descriptive technique in which one individual or group is studied in depth in the hope of revealing universal principles

placebo effect

experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition, which the recipient assumes is an active agent.

correlation

A measure of the extent to which two factors vary together, and thus of how well either factor predicts the other.

correlation coefficient

a statistical index of the relationship between two things (from -1 to +1)

standard deviation

a computed measure of how much scores vary around the mean score

positive correlation

as one variable increases, the other tends to increase

negative correlation

as one variable increases, the other tends to decrease

reliability

consistency of measurement

inferential statistics

numerical data that allow one to generalize- to infer from sample data the probability of something being true of a population

descriptive statistics

numerical data used to measure and describe characteristics of groups. Includes measures of central tendency and measures of variation.

mean

the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores

median

the middle score in a distribution; half the scores are above it and half are below it

mode

the most frequently occurring score(s) in a distribution

range

the difference between the highest and lowest scores in a distribution

skewed distribution

a representation of scores that lack symmetry around their average value