Why is an experiment
different from the descriptive methods we discussed in class?
Tests
hypothesis by comparing the behavior of 2 or more groups of participants under
very controlled conditions.
Groups
are treated as similarly as possible EXCEPT for the critical variable (the independent
variable) that the researcher is interested in. The researcher
intentionally manipulates or varies the independent variable to study its
impact on behavior, while keeping everything else constant.
Hypothesis
A
tentative statement or prediction about the relationship between 2 or more
variables
Examples:
Consumption
of alcohol will impair short-term memory.
Relaxation
training will reduce test anxiety and improve test performance.
Random Assignment
To
make the 2 groups as equal as possible initially, most often participants will
be randomly assigned
to 1 group or the
other. This assures that there are no systematic differences between the
groups.
Some Basic Definitions:
Independent variable- what the researcher manipulates or varies; the thing that is different
in the experimental group versus the control group.
Dependent variable
- the behavior that is observed, measured, tested; the actual data collected
from both groups.
The
researcher must define both the independent & dependent variables as they
will be used in the study: These are operational definitions
Definitions continued:
Experimental group
- the group of participants exposed to the independent variable that the
researcher is really interested in
Control group -
the group NOT exposed to the independent variable of interest but rather to
some substitute control condition.
Can you identify the above in some examples?
Hypothesis:
Damage to the
hypothalamus will lead to a change in eating behavior.
Independent
Variable?
Dependent
Variable?
Experimental
Group?
Control Group?
A Creativity Study