Invitation to Psychology

38 Chapter 1 What Is Psychology?

and double-blind procedures can be used to prevent the expec-

tations of the participants or the experimenter from affecting

the results. Because experiments allow conclusions about cause

and effect, they have long been the method of choice in psychol-

ogy. However, like laboratory observations, experiments create a

special situation that may call forth behavior not typical in other

environments. Many psychologists, therefore, have called for

more field research.

Evaluating the Findings

• Psychologists use descriptive statistics, such as the arithmetic
mean and the standard deviation, to summarize data. They use
inferential statistics to find out how impressive the data are.

• Significance tests tell researchers how likely it is that the re-
sults of a study occurred merely by chance. The results are
said to be statistically significant if this likelihood is very low.
Confidence intervals help researchers evaluate where the real
population mean is likely to be if the study could be repeated
over and over.

• Choosing among competing interpretations of a finding can be
difficult, and care must be taken to avoid going beyond the

facts. Sometimes the best interpretation does not emerge until

a hypothesis has been tested in more than one way, such as by

using both cross-sectional and longitudinal methods.

•   Statistical significance does not always imply real-world impor-

tance because the amount of variation in the data accounted

for by the independent variable may be small. Therefore,

many psychologists are now turning to other measures. The

effect size provides a way of describing the strength of an

independent variable’s influence on the dependent variable.

Meta-analysis is a set of techniques for combining data from

related studies to determine the overall explanatory strength of

an independent variable.

Taking Psychology With You

•   Statistics help scientists understand the complexity of behav-

ior, but statistics can also be misrepresented and misused.

Critical thinkers should ask how numbers were calculated,

consider percentages that reveal absolute risk rather than

just relative risk, ask how terms were defined, look for a con-

trol group, and be cautious about inferring causation from a

correlation.

psychology 4

empirical 4

phrenology 5

Wilhelm Wundt 6

trained introspection 6

functionalism 6

William James 6

Sigmund Freud 6

psychoanalysis 6

biological perspective 6

evolutionary psychology 6

learning perspective 6

behaviorists 6

social-cognitive learning

theorists 7

cognitive perspective 7

sociocultural perspective 7

psychological practice 9

basic psychology 9

applied psychology 9

counseling psychologist 10

school psychologist 10

clinical psychologist 10

psychotherapist 10

psychoanalyst 10

psychiatrist 10

critical thinking 13

hypothesis 14

operational definition 14

principle of falsifiability 15

confirmation bias 15

theory 16

replicate 17

representative sample 18

descriptive methods 19

case study 19

Key Terms

Use this list to check your understanding of terms and people in this chapter. If you have trouble with a term, you can find it on

the page listed.