1. A researcher keeps detailed records of the behavior of a newborn child for two weeks. He is:

4. Control conditions are set up to make sure that the ______________________________________________variable does indeed cause the effect noted in the_____________________________ variable.

5. An experimenter is interested in the effects of incentive on the learning of a maze by rats. Some of the rats received one food pellet when they had reached the end of the maze; a second group received two pellets each and a third group received four pellets each. After six days the experimenter recorded the percentage of correct choices made by the animals. Which graph shows the data plotted according to the usual convention?

6. Which is true of naturalistic observation?
a. It preceded scientific experimentation historically.
b. It is still in active use as part of science.
c. Naturalistic observations can be summarized.
d. All of the above.
Check your answers on the KEY

Now to the EXERCISES that follow.


An observer has decided to study the behavior of a certain species of bird. He sits in an office with a pair of binoculars, watching a nearby nest. He uses his dictaphone to record his observations, which his secretary will type later.

Which is true of this method of observation?

a. Dependent and independent variables have been identified.
b. It is an example of naturalistic observation.

c. The record of his observations would probably lead all independent reviewers to the same conclusion.


After several weeks of bird watching the researcher decides to compare the time it takes 2 different species of bird to build a nest. He locates one bird from each species and records the time it takes each to build a nest. His data is summarized in a table.
Number of Days to Build a Nest
Bird 118
Bird 212

Which is true of these new observations?
a. They represent an example of scientific experimentation.
b. They proved that species 1 takes 50% longer to build a nest than species 2.
c. The method of observation is unchanged from that employed before (See 1 above).


In contrast to the method of naturalistic observation, the experimental method goes beyond merely observing and recording by requiring the researcher to manipulate some condition of the situation under study.


The conditions that a researcher manipulates are called the independent variables. The conditions that change as a result of his manipulations are called the dependent variables. In the above example the amount of alcohol ingested is an independent variable (the experimenter controls its ingestion) and the reaction time, which varies, is the dependent variable. Consider the following experiment.

Cazden (1965) compared the effectiveness of enlarging upon children's remarks in advancing language development in children. She selected groups of children of approximately the same age and language development stage. She spent forty minutes a day for three months with each child from one group, enlarging every remark made by the child. For example, if the child said, "Baby hungry," the experimenter would say, "Yes, he wants to eat." The "enlarged" group showed considerable advancement over the group that was allowed to develop normally.


1. Independent variable.
2. Dependent variable.
a. rate of development
b. nature of the remarks
c. the group that developed normally

The control group in the experiment described above was_________________________________________________4

In order to be certain that any change in the dependent variable was due to a change in the independent variable, the experimenter sets up a_________________________________3

ANSWERS for above

1 b
2 b
3 control group, or control condtion
4 the group that developed normally
6 c

In the nineteenth century, a German psychologist, Ebbinghaus, performed many experiments in learning and retention.. He devised the "nonsense syllable," two consonants connected by a vowel, for use in his tests. He used these syllables to test the influence of various conditions on learning and retention.. One factor tested was the effect of time on the amount retained. He would read the list as many times as necessary for the subject to give an errorless reproduction. One way in which Ebbinghaus measured retention was by a savings score. (This will be explained in later units.)

It is a convention that the independent variable forms the horizontal axis and the dependent forms the vertical axis. Which is correct for Ebbinghaus's experiment?

a. Time is on the horizontal axis

b. Retention (savings score) is on the horizontal axis _____________________________________2

It is possible that a variable other than the one we manipulated has caused me change in the dependent variable. For example, we know that a cup of coffee will cool whether we add cream or not. How can it be verified that cream does cool the coffee?

_________________________________ 5

The control condition is one in which every factor is identical to the experimental condition, except that the independent variable is eliminated or held constant. This is done to assure:


ANSWERS for above

2 a
3 b
5 a


A researcher is interested in finding out if courses in American Government affect students' attitudes toward war and selects 300 students to participate in an experiment. All the students fill out a questionnaire designed to measure their attitudes toward the war. Then, 150 of the students enroll in a one-semester course in American Government. The researcher does not know who is teaching the course. At the end of the semester he administers a similar test on attitudes, again to all 300 students.

1. This researcher is using the_____________________________________method.

2. The course in American Government is the _______________________________variable.

3. The students' attitudes toward war is the________________________________________variable.

4. The students who did not take the course functioned as a(n)______________________________________ group.

5. Which is true of naturalistic observation?




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August 28, 2007