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conditions other than those related to the hypothesis under investigation
a） A double…blind control refers to a procedure in which both the
participant and the experimental assistant administering a treatment
are blind to； or unaware of； the experimental condition to which the
participant is assigned
b） A placebo control is an experimental condition in which participants
believe that they are receiving a treatment that may be effective； but in
which they are actually receiving a treatment that is known not to be
effective。 By paring the placebo control group with the group of
participants that received the actual treatment； researchers can
determine how much change in the participants is due to their beliefs
（placebo effect） and how much is due to the treatment itself。
2。 Research designs： Properly designed experiments are another way of ensuring
that alternative explanations are kept to a minimum。 By determining which
alternative explanations are likely to be serious petitors to the explanation
directly under investigation； researchers can incorporate conditions that test
these alternative explanations in their research。
3。 Random assignment is one of the most important aspects of research design。 It
helps ensure that the participants in each condition are as similar to each
other as possible； because each participant has the same chance of being in
each condition。
4。 Because researchers would like to be able to generalize their findings from
their sample； the participants in their study； to the larger population from
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CHAPTER 2： RESEARCH METHODS IN PSYCHOLOGY
which the sample was drawn； the sample should be representative of the
population； or a representative sample
5。 In between…subjects designs； participants are randomly assigned to one
experimental condition or one control condition。 There may be more than one
experimental condition； in which participants are exposed to different
treatments； and there may be more than one control condition； in which
participants are not exposed to those treatments。 This allows researchers to
account for alternative explanations。 However； each participant is only in one
condition。
6。 In within…subjects designs； each participant serves as his or her own control； as
they are assigned to at least two conditions； a control condition and an
experimental condition。 In a within…subjects experiment； a participant may be
given a placebo； such as an inert sugar pill； and then given a treatment that is
hypothesized to be effective。 By paring each participant’s change between
the control （placebo） condition and the treatment condition； researchers can
determine the efficacy of the treatment much more accurately。
7。 A third type of research design is known as the A…B…A design。 In the A…B…A
design； each participant is assessed in a baseline condition； then given an
experimental treatment； and then reassessed in the baseline condition。 The AB…
A design is a with…in subjects design。
F。 Correlational methods are used to determine to what extent two variables； traits； or attitudes are
related
1。 The standard measure of correlation is a statistic called a correlation coefficient
represented by “r”。 r can vary between …1。0 and ＋1。0； where …1。0 represents a
perfect negative correlation； and ＋1。0 represents a perfect positive correlation。
A correlation of 0 indicates that there is no relationship between the variables。
In much research on personality traits； r’s are modest–between 。10 and 。30。
2。 A positive correlation means that as one set of two scores increases； so does the
other set。 For example； as height increases； weight also tends to increase。
3。 A negative correlation means that as one set of scores increases； the other set
decreases。 For example； as physical exercise increases； weight tends to
decrease。
4。 A critical caveat to the correlational method is that correlation does not imply
causation。 Simply because a researcher finds that two variables are related
does not mean that one variable necessarily causes the change in the other
variable。 This warning is important because it is difficult； if not impossible； to
know which variable is causing the change in the other； and there is always
the possibility that a third； unknown； variable is causing the change in both or
is the key mediating variable between them。
a） Psychological researchers have used the experimental method to
demonstrate that subliminal self…help tapes offer nothing more than
placebo effects。
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PSYCHOLOGY AND LIFE
III。 Psychological Measurement
A。 Two main challenges to psychological measurement： Achieving Reliability and achieving Validity
1。 Reliability refers to the consistency or dependability of results from research。 If
we consider throwing darts at a dartboard； reliability would be measured by
how closely the darts group together。 If the darts reliably hit the same spot；
even if it is not the bull’s…eye； the throws are reliable。
2。 Validity refers to how accurately the research actually measures the
psychological variable under study。 For instance； does the self…esteem scale
used in research accurately measure self…esteem； or does it measure something
closer to self…presentation style？ If we again consider throwing darts； validity
would be measured by how closely the darts came to the spot that the thrower
wanted to hit。 If you wanted all of your darts to hit the bull’s…eye and they did；
your throws would have been both valid （they hit the intended mark） and
reliable （all of them hit the same mark）。
B。 Self…Report Measures
1。 Self…report measures are written or spoken responses to questions posed by the
researcher
a） A questionnaire is a self…report measure on which a respondent replies
to a written list of questions
b） Questions on self…report measures may be open…ended； which allow
respondents to answer freely in their own words； or forced choice；
which provide respondents with a number of alternatives； such as
“yes；” “no；” and “undecided；” from which to choose。
c） An interview is an interactive dialogue between a researcher and an
individual for obtaining detailed information。 Good interviewers
establish positive rapport with interviewees； which facilitates self…
disclosure and responses that are more honest。
C。 Behavioral Measures and Observations
1。 Behavioral measures and observations are ways to study overt actions and
observable； recordable reactions
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CHAPTER 2： RESEARCH METHODS IN PSYCHOLOGY
a） Planned； controlled； systematic observation is an important source of
behavioral data
b） Direct observation involves observation of behavior that is clearly
visible and easily recorded
c） Naturalistic observation occurs in a natural setting； such as the
playground or in the wild； rather than in an artificial； highly contrived
laboratory setting
2。 Case study research focuses on a single individual rather than on large
numbers of participants。
IV。 Ethical Issues in Human and Animal Research
A。 At the core of the ethical treatment of both humans and animals is the question of whether the
potential gains from the proposed research outweigh the expected or potential costs。 Colleges have
established review boards to help researchers make this decision； and the American Psychological
Association （APA） has established guidelines to ensure that research is conducted ethically。 For
humans； these guidelines include the following：
B。 Informed Consent
1。 Whenever possible； participants must be informed about the nature of the
experiment in which they may participate and； after being informed； must
consent to participate。 They are also informed that their consent is conditional
and that they can withdraw it at any time without penalty。
C。 Risk / Gain Assessment
1。 Not only do researchers have a responsibility to weigh potential risks of an
experiment against its potential benefits； they also have a responsibility to do
everything in their power to minimize risk to participants； whether they are
human or nonhuman； and to optimize the possible be