Unit 2 Research Methods




The scientific attitude reflects an eagerness to skeptically scrutinize competing ideas with an openminded humility before nature. This attitude, coupled with scientific principles for sifting reality from illusion, prepares us to think criti cally. Two reliable phenomena—hindsight bias and judgmental overconfidence—illustrate the limits of everyday intuition and our need for scientific inquiry and critical thinking.

Psychologists construct theories that organize observations and imply testable hypotheses. In their research, they use case studies, surveys, and naturalistic observation to describe behavior; correlation to assess the relationship between variables; and experimentation to uncover causeeffect relationships. Researchers use statistics to describe their data, to assess relationships between variables, and to determine whether differences are significant.

This unit concludes by briefly answering several questions that students commonly ask aboutpsychology. These include concern over the simplification of reality in laboratory experiments, the generalizability of research in terms of culture and gender, the purpose of animal studies, the adequacy of research ethics, and the potential misuse of psychology’s knowledge.



The Need for Psychological Science

The hindsight bias, also known as the I-knew-it-all-along phenomenon, is the tendency to believe, after learning an outcome, that one would have foreseen it. Finding out that something has happened makes it seem inevitable. Thus, after learning the results of a study in psychology, it may seem to be obvious common sense. However, experiments have found that events seem far less obvious and predictable beforehand than in hindsight. Sometimes, psychological findings even jolt our common sense.

Our everyday thinking is also limited by our tendency to think we know more than we do. Asked how sure we are of our answers to factual questions, we tend to be more confident than correct. Students’ predictions of their future behaviors are similarly overconfident. Experts’ predictions of world events made with 80 percent confidence were right less than 40 percent of the time.

Science takes an empirical approach, basing decisions or conclusions on observable evidence.  The scientific attitude reflects a hard-headed curiosity to explore and understand the world without being fooled by it. The eagerness to skeptically scrutinize competing claims requires humility because it means we may have to reject our own ideas. This attitude, coupled with scientific principles for sifting reality from illusion, helps us winnow sense from nonsense. It carries into everyday life as critical thinking in which we examine assumptions, discern hidden values, evaluate evidence, and assess conclusions.


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How Do Psychologists Ask and Answer Questions?


A useful theory effectively organizes a wide range of observations and implies testable predictions, called hypotheses. By enabling us to test and reject or revise a particular theory, such predictions give direction to research. They specify in advance what results would support the theory and what results would disconfirm it. As an additional check on their own biases, psychologists report their results precisely with clear operational definitions of concepts. Such statements of the procedures used to define research variables allow others to replicate, or repeat, their observations. Often, research leads to a revised theory that better organizes and predicts observable behaviors or

The case study is the method by which psychologists analyze one or more individuals in great depth in the hope of revealing things true of us all. While individual cases can suggest fruitful ideas, any given individual may be atypical, making the case misleading.

The survey looks at many cases in less depth and asks people to report their behavior or opinions. Asking questions is tricky because even subtle changes in the order or wording of questions can dramatically affect responses. In everyday experience, we are tempted to generalize from a few vivid but unrepresentative cases. The survey ascertains the self-reported attitudes or behaviors of a population by questioning a representative, random sample.

Naturalistic observation consists of observing and recording the behavior of organisms in their natural environment. Like the case study and survey methods, this research strategy describes behavior but does not explain it.

When surveys and naturalistic observations reveal that one trait or behavior accompanies another, we say the two correlate. A correlation coefficient is a statistical measure of relationship. A positive correlation indicates a direct relationship, meaning that two things increase together or decrease together. A negative correlation indicates an inverse relationship: As one thing increases, the other decreases, and vice versa. Researchers depict scores on graphs called scatterplots; each point plots the value of two variables. The correlation coefficient helps us to see the world more clearly by revealing the extent to which two things relate.

Perhaps the most irresistible thinking error is to assume that correlation proves causation. Correlation reveals how closely two things vary together and thus how well one predicts the other. However, the fact that events are correlated does not mean that one causes the other. Thus, while correlation enables prediction, it does not provide explanation.


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Illusory correlation, the perception of a relationship where none exists, often occurs because our belief that a relationship exists leads us to notice and recall confirming instances of that belief. Because we are sensitive to unusual events, we are especially likely to notice and remember the occurrence of two such events in sequence, for example, a premonition of an unlikely phone call followed by the call.

Illusory correlation is also a result of our natural eagerness to make sense of our world. Given even random data, we look for meaningful patterns. We usually find order because random sequences often don’t look random. Apparent patterns and streaks (such as repeating digits) occur more often than people expect. Failing to see random occurrences for what they are can lead us to seek extraordinary explanations for ordinary events.

The experiment is a research method in which the investigator manipulates one or more factors to observe their effect on some behavior or mental process, while controlling other relevant factors. If a behavior changes when we vary an experimental factor, then we know the factor is having a causal effect. In many experiments, control is achieved by randomly assigning people either to an experimental group, which is exposed to the treatment, or a control group, which is not exposed. Often, the research participants are blind (uninformed) about what treatment, if any, they are receiving. One group might receive the treatment, while the other group receives a placebo (a pseudotreatment). Often, both the participant and the research assistant who collects the data will not know which condition the participant is in (the double-blind procedure). The placebo effect is well documented. Just thinking one is receiving treatment can lead to symptom relief.


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The independent variable is the experimental factor that is manipulated. It is the variable whose effect is being studied. The dependent variable is the variable that may change in response to the manipulations of the independent variable. It is the outcome factor. Other factors, which can potentially influence the results of the experiment, are called confounding variables.

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Statistical Reasoning in Everyday Life


Statistics help us to organize, summarize, and make inferences from data. They help us see and interpret what the unaided eye might miss. Statistical principles enable us to evaluate big, round, undocumented numbers that often misread reality and mislead the public. One way to organize statistical data is to convert the data into a simple bar graph.

The mode is the most frequently occurring score in a distribution. The mean is the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores. If the distribution is skewed by even a few extreme scores, the mean will be biased. The median is the middle score in a distribution; half the scores are above it and half are below it.

Click on link  below for a video demonstrating how to find the mean, mode, and median:



The range of scores—the gap between the lowest and highest score—provides only a rough estimate of variation. The more standard measure of how scores deviate from one another is the standard deviation. It better gauges whether scores are packed together or dispersed because it uses information from each score. Many types of scores are distributed along a bell-shaped curve, or a normal curve.

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Important principles to remember in making generalizations include the following:

1. Representative samples are better than biased samples. We are particularly prone to overgeneralize from vivid cases at the extremes.

2. Less-variable observations are better than those that are more variable. Averages are more reliable when derived from scores with low variability.

3. More cases are better than fewer. Small samples provide less reliable estimates of the average than do large samples.

Psychologists use tests of statistical significance to help them determine whether differences between two groups are reliable. When the averages of the samples drawn from the groups are reliable, and the difference between them is relatively large, we say the difference has statistical significance. This means that the difference very likely reflects a real difference and is not due to chance variation between the samples. Given large enough or homogeneous enough samples, a difference between them may be statistically significant yet have little practical significance.


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Frequently Asked Questions About Psychology


The experimenter intends the laboratory experiment to be a simplified reality, one in which important features can be simulated and controlled. The experiment’s purpose is not to re-create the exact behaviors of everyday life but to test theoretical principles. It is the resulting principles—not the specific findings—that help explain everyday behavior.

Although culture shapes our specific attitudes and behaviors, the principles that underlie them vary much less. Our shared biological heritage unites us as members of a universal human family. Studying gender differences is not only interesting but also potentially beneficial in preventing conflict and misunderstanding in everyday relationships. It is important to remember, however, that psychologically as well as biologically, women and men are overwhelmingly similar.

Some psychologists study animals out of an interest in animal behaviors. Others do so because knowledge of the physiological and psychological processes of animals enables them to better understand the similar processes that operate in humans. Because psychologists follow ethical and legal guidelines, animals used in psychological experiments rarely experience pain. The debate between animal protection organizations and researchers has raised two important issues: Is it right to place the well-being of humans above that of animals, and what safeguards are in place to protect the well-being of animals in research? Many professional organizations and funding agencies have developed extensive guidelines for the humane use of animals.

Ethical principles for the treatment of human participants urge investigators to obtain informed consent, protect subjects from harm and discomfort, treat information about individuals confidentially, and fully explain the research afterward (debrief the participants).

Click link below to find out more about ethical guidelines in conducting research:



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*Work Cited:  All summary notes come from *Myers Pyschology for AP, Lecture Guides (2011 Worth Publishers)