There are two different foundations that support psychology.
As a field of study, it is built upon the ideas and perspectives that have shaped it historically; as a science, it is built upon the principles of good research design and a variety of statistical techniques.
In this chapter, we will look at the way people thought about brain and behavior before modern psychology and the frameworks through which we view these ideas.
We will discuss how we use research and experimentation to learn more about how humans and other animals think.
Psychology is a relatively new field compared to other disciplines that have been around for hundreds or even thousands of years.
The science of psychology began in 1879 with the work of German medical doctor and sensation researcher Wilhelm Wundt.
The first psychology laboratory was founded by Wundt at the University of Leipzig.
The study of psychology began in 1879.
Throughout history, people have posed psychological questions, asking how the mind works, why human beings think, feel, and act in the ways they do, and what makes individuals different from one another.
The roots of psychology can be traced back to Greek antiquity.
Understanding how psychology came to be the science that it is today can help you appreciate how it came to be.
The philosopher thought that the perfectibility of the soul was the key to happiness.
The Socratic method was used to bombard prominent Athenian citizens with questions, urging them to examine their lives, their actions, and their beliefs, all for the sake of bettering their souls.
The Greek word for "soul" is exactly what the word "psychology" originally meant.
Ancient Greek philosophers played a role in psychology's history.
Plato and Aristotle debated about the location of thinking in the human body.
Plato believed that the brain was the source of thoughts, while Aristotle believed that the heart was the source of mental processes.
It's important to note that Plato's view is not as far-fetched as it might seem.
Even though he wasn't right about the heart's role in mental processes, he developed a number of ideas about psychology that were highly influential for many centuries.
There were three levels of souls according to his work, On the Soul.
The soul of living things is called the nutritive soul and it regulates nutrition, growth, and reproduction.
The sensible soul is shared by all animals.
The rational soul is only found in humans.
Understanding human psychology required appreciation of all three types of souls, because human beings are not merely rational, but also possess sensible and nutritive capacities shared with other organisms.
Other intellectual traditions contributed to psychology's foundation.
During the Islamic Golden Age, a prominent scholar by the name of Hasan Ibn al-Haytham conducted experiments on vision and wrote a seven-volume treatise.
The emission theory of vision, which held that the eyes send out rays of light in order to see, was discredited by the extensive studies of the eye's structure and function.
His discovery is seen as the first psychological conclusion based on systematic research, though it occurred several hundred years before he founded his laboratory.
European philosophy had an impact on psychology.
Rene Descartes tried to establish a new foundation for human knowledge by questioning everything he could.
He arrived at what he believed to be a certain truth after clearing away any doubts.
Even if he was wrong about everything else, he could not be wrong about the fact that he was a thinking thing.
The idea that mind and body are separate substances that operate according to distinct principles formed the basis of mind-body dualism.
The idea that the mind functions according to its own set of rules that could theoretically be discovered by specialized scientists of the mind--psychologists was an influence on psychology.
John Locke wanted to understand how the mind works by studying its contents.
Locke believed that all knowledge comes from experience and that some ideas are innate.
Locke said that all the contents of the mind can be traced to sense experience.
He thought of the human mind as a blank slate, a blank slate upon which experience would write, shaping each mind to become a unique person.
Locke believed that human beings could be molded to become just about anything, simply based on the experiences that they had been exposed to.
Locke's empirical approach was used by British philosophers to develop more systematic accounts of how the mind worked.
The "Associationist School" tried to explain the mind's operation through the association of ideas.
According to this view, even the most complex thoughts and feelings that we find in our minds are built up from simple impressions and principles of association.
A number of principles of association were suggested by Scottish philosopher David Hume.
Early scientific psychologists, such as Titchener, had a lasting impact on how they understood the mind, as a result of the explanations that Hume used to explain a wide variety of mental phenomena.
Philosophers were not the only people whose work was related to psychology.
Charles Darwin contributed to psychology's foundation.
His accounts of the origin of species and of evolution through natural selection implied a continuity between humans and nonhuman animals, suggesting that the mental lives of human beings must not be so different from those of other animals.
Darwin identified a number of "human" qualities in the behavior of animals.
The "fight or flight" response can be found in human beings.
Darwin could explain the similarities and differences between humans and other animals.
The similarities resulted from the common ancestry shared by all animals, while the differences arose from the distinctive environmental challenges humans and other species faced in their struggle to survive and reproduce.
Darwin's theory of evolution has had a huge impact on psychology, particularly for functionalism in the late nineteenth century.
The establishment of psychology was aided by the early work in physiology.
The controversial approach known as phrenology was formulated by German scientists.
They claimed to have identified 35 different mental faculties that correspond to a specific location in the brain.
Measuring the bumps on a person's skull could reveal how developed these faculties were and how likely that person would be to engage in particular behaviors.
The claims of phrenology have been thoroughly discredited, but contemporary psychologists agree that there is a strong connection between the brain and human behavior.
Other German scientists focused on a field called psychophysics, which looked at the relationship between incoming physical stimuli and the sensations they produce.
The absolute threshold and the just-noticeable difference are two concepts that are still accepted by contemporary psychologists of sensation.
One of the most influential German physiologist was Hermann von Helmholtz, who conducted research on vision, hearing, and nerve impulses.
The ophthalmoscope, invented by Helmholtz, is used to observe the retina and is one of the most significant contributions to the study of color vision and depth perception.
He brought his musical training to bear in learning how the ear distinguishes between pitches.
Helmholtz was able to detect and measure the speed of signal transmission through a nerve.
The findings of Helmholtz are relevant to modern psychologists of sensation and perception.
Even if psychology's history only lasts a century and a half, it had a long and illustrious prehistory.
Awareness of the philosophers and scientists discussed here should be sufficient for the AP Psychology exam, even though many other ideas from a vast array of thinkers also influenced the early development of psychology.
The development of the science in the United States and Europe will be focused on now that you have a sense of the major roots of psychology.
The founding fathers of psychology during the late nineteenth century and early twentieth century were Edward Titchener and William James.
The study of immediate experience is what psychology is about.
He characterized sensations and feelings as structures of consciousness.
He asked his subjects to report the intensity and quality of their sensations after he presented them with various kinds of lights, sounds, andtextures.
He asked them to look within themselves, a practice known as introspection, which is the precise examination and description of conscious experience.
The stimuli were changed, the process was repeated, and the changes in people's reports were documented.
Like Locke and Hume before him, Wundt embraced empiricism and tried to learn about human psychology through detailed observations of experience.
Edward Titchener named the approach structuralism.
Edward B. Titchener moved to the U.S. in 1892, where he became a psychology professor at Cornell University and founded the first psychology laboratory in the U.S. Titchener created English translations of 11 German works of psychology in order to bring it to the United States.
The procedures for qualitative and quantitative experiments were outlined in Titchener's manual on laboratory research.
He proposed a study of the adult mind and a description of conscious experience.
Harvard University's William James was a philosopher who emphasized what the mind does rather than what the mind is.
James believed that the study of how consciousness works to aid human beings in adapting to their environment was the goal of psychology.
James's approach became known as functionalism because of his focus on the mind's functions.
According to the functionalist approach, mental states are identified by what they do rather than what they are composed of.
James published The Principles of Psychology in 1890, which was the first psychological textbook and covered a wide range of topics, including consciousness, emotions, habits, and the will.
James is well known as the founder of American psychology.
James was instrumental in promoting and developing Darwin's vision of human evolution and was adamant that the mind and consciousness would not exist if they were not useful.
Further development of psychology would come from this more biological orientation.
All psychological phenomena can be understood in terms of biological processes.
The mind can be reduced to the function of the brain and nervous system.
Neuroscience is often used to find the biological underpinning of behavior, as well as to genetics and evolution to understand how the brain developed.
All would agree that thoughts, feelings, and behaviors have biological causes.
It helps to assess how the nervous and endocrine systems function, and how changes in the structures of these systems can affect behavior.
For example, psychologists who use a biological approach may examine how prescribed drugs that treat depression affect behavior through their interactions with specific neurotransmitters or hormones.
Information about what psychological characteristics are heritable is revealed by the study of genetics and inheritance patterns.
Twin studies are discussed in on the Biological Bases of Behavior by many contemporary biological psychologists.
Studies of identical twins who have the same genetics but grew up in different environments allow a better gauge of whether nature or nurture has a bigger impact on the development of specific traits.
Attempting to explain human psychology through genetics has significant drawbacks.
Early in psychology's history, some biological psychologists speculated that criminal behavior was due to the influence of genetics.
Eugenics advocates believed that the human species could be improved by removing undesirable characteristics from the genes.
Criminals, the developmentally challenged, and other individuals deemed to have undesirable tendencies were called for mandatory sterilization by some eugenicists.
Eugenics caused a lot of turmoil and bloodshed and even played a role in leading to the bloodiest conflict in human history, World War II.
Behaviorism maintains that the proper subject matter of psychology is observable and measurable.
Behaviorists think the mind is a black box and cannot be studied scientifically.
Animal learning was studied by early behaviorists.
The dogs in Ivan Pavlov's lab salivated when they saw the lab worker.
Classical conditioning is a theory of learning in which an organisms learns to form a new association between two stimuli.
The theory of prediction and control was advocated by John B. Watson.
Little Albert, a nine-month-old infant, developed a fear of white rats and similar-looking objects as a result of his experiment with Watson.
The Little Albert study is a classic example of a behaviorist approach to learning.
The founder of behaviorism is john watson.
The behavioral approach to psychology was further developed by Burrhus Frederic Skinner with his theory of operant conditioning.
Behavior can be shaped in novel ways with this type of learning.
Skinner was able to train pigeons to make circles.
From the 1920s to the 1950s, behaviorism was the dominant approach to psychology in the United States.
Native German-speaking scholars in Germany, Austria, and Switzerland followed different approaches to scientific psychology, despite the fact that psychologists in the United States came to consider behaviorism the only proper method for scientific psychology.
The founding of Gestalt psychology in the early twentieth century was a reaction to the structuralism of the time.
The components of consciousness were not as important as the whole, according to the Gestalt school.
The mind should be studied in all its complexity, rather than being separated into components.
The psychology of perception, learning, behavior, and other aspects must be examined as wholes.
When two lights are flashed in succession under certain conditions, an illusion of continuous motion can be created.
The mind imposes its own patterns of organization on the stimuli it receives, rather than just reproducing them, as a result of this and other experiments.
The less structured form of introspection known as "phenomenology" was used by psychologists to explore questions about individual perception of motion, size, and color.
Sigmund Freud, an Austrian physician specializing in neurological disorders, encountered patients in his medical practice who were suffering from physical symptoms for which he couldn't detect a biological cause.
Freud developed the technique of free association, in which a patient is encouraged to talk freely, expressing ideas immediately as they come to mind, with the hope that this would eventually uncover the unconscious basis of the patient's problems.
According to Freud, there are many unconscious conflicts that cause people to be uncomfortable.
Freud believed that the symptoms were caused by repressed childhood memories and other conflicts buried deep in the unconscious.
Freud used free association, hypnotism, and dream analysis to uncover patients' repressed conflicts.
Carl Jung was an associate of Freud and focused on the unconscious but developed a different perspective.
Jung believed that people seek spiritual meaning during the course of their lives.
He proposed the existence of a collective unconscious, a repository of instincts and symbols shared by all human beings.
Alfred Adler, an Austrian colleague of Freud, put an emphasis on an individual's need for belonging, the desire to be a part of a community or other social group.
He wanted to create a sense of equality between the patient and therapist.
Adler is known for being the first real community psychologist because of his focus on social interests and improving community health by means of public education.
Psychodynamic psychology is a term used to describe the approaches of Freud, Jung, Adler, and others.
The treatment of patients through talk therapy was influenced by psychodynamics.
Humanistic psychology evolved in the 1950s and 1960s as a reaction to the psychodynamic approach of Freud and his disciples.
The pessimistic view of human nature implicit in behaviorism's denial of human agency and reduction of human beings to machines was rejected by the Humanists.
Human beings have the power to shape their own destinies according to the humanistic approach.
The ultimate goal of the psychologist is to help people realize their full potential.
The approach was influenced by two major figures.
A hierarchy of needs that defines what human beings require to live a fulfilling life is what Abraham Maslow is known for.
Lower-level needs must be satisfied before higher-level needs.
The need for self-actualization is at the top of the hierarchy.
For more on self-actualization and the hierarchy of emotions, see Motivation, Emotion, and Personality.
Carl Rogers advocated the clientcentered approach to therapy.
Client-centered therapists try to facilitate self-acceptance and self-understanding by conveying empathy, warmth, and the belief that no matter what the client says or does, he or she is still a valuable person.
Rogers' approach can be found on Clinical Psychology.
While the humanists were critical of behaviorism for denying free will, another group of psychologists came to lodge a different criticism, rejecting behaviorism's insistence that the mind is a "black box" not susceptible to scientific study.
The cognitive revolution was a radical shift in the approach to psychology that sought to understand the cognitive processes that underlie behavior.
Structuralists and functionalists were interested in many areas, but cognitive psychologists sought to understand both the structures and functions of the brain.
The cognitive revolution spawned research into a wide array of cognitive processes, including memory, language, thought, and attention.
The importance of semantic relatedness--relatedness on the basis of meaning is one of the characteristics that influenced people's ability to store and recall information.
Study participants have an easier time recalling words that are related than words that are not.
The recency effect, in which people are better able to remember items presented at the end of a list, is one of the phenomena revealed by other studies of memory.
The work of Noam Chomsky made the psychology of language an important area of study for cognitive psychologists.
Chomsky believes that all languages have the same underlying logic.
He maintained that the human capacity for language is innate, rather than learned, based on observations that children are exposed to only a small subset of words and expressions when they learn their first language, and yet come to acquire a nearly unlimited ability to say anything that comes to mind.
Other psychologists focused on other aspects of cognitive functioning.
Bruner studied people's responses to stimuli.
Intellectual ability develops in stages from infancy to adulthood and is influential in the field of education.
The theory of cognitive dissonance was introduced by Leon Festinger, a cognitive psychologist and social psychologist.
Festinger maintained that cognitive dissonance can cause people to change their beliefs.
You can find more on cognitive dissonance on Social Psychology.
The psychology of the individual is emphasized in many of the psychological approaches.
The great diversity of individuals that we find in the world today is a result of how social and cultural contexts influence human behavior.
Lev Vygotsky is considered to be the pioneer of the sociocultural approach.
Vygotsky studied how children learn in a cultural context.
Children interact with other people in a way that influences their cognitive development.
Vygotsky acknowledged that parents, teachers, older siblings, and others can shape instructional methods.
The cognitive skills that arise from learning methods are specific to the culture of the child.
More on Vygotsky can be found on Developmental Psychology.
The cognitive approach is popular in many areas of psychology.
One must understand the way that people think, remember, process information, and reason about the world in order to understand the individual.
The focus of contemporary cognitive psychology has changed to acknowledge sociocultural influences on cognitive development.
Evolutionary theory has made a resurgence in recent years.
The concept of kin selection has been used as a way to explain altruistic behavior, which might be at odds with evolutionary theory.
Evolutionary psychology tries to explain a wide range of human behaviors.
The wide array of approaches that emerged during psychology's history gave contemporary psychologists greater flexibility in studying the subject matter that interests them.
A psychologist who wants to understand the effects of traumatic brain injuries is more likely to use a biological approach, a researcher who wants to study attitude formation and change is more likely to use cognitive psychology and theories of persuasion, and a scholar who wants to study cultural differences is more likely to use a Students of psychology are encouraged to be pluralistic in their initial studies, understanding the whole panoply of perspectives that makes psychology the rich discipline it is today.
There are many theories that explain different aspects of human behavior.
The AP Psychology exam expects you to understand the benefits and limitations of using theories to explain human psychology, in addition to requiring knowledge of specific psychological theories.
There are some advantages to using theories.
It is possible to make predictions about how people will behave in the future with the help of theories.
The ability to predict responses can be used to take control of the circumstances of our lives, to use characteristics of our psychology to grow as people, and to bring about positive change in the world more effectively.
In psychology, theories help researchers to understand their experimental results better and to design new experiments to test hypotheses derived from those theories.
Theories can be refined in light of the empirical data, with unexpected results leading to amendments, exceptions, or even entirely new theories.
Theory and data can lead to a better understanding of human psychology.
Negative outcomes can be caused by the strengths of these theories.
The ability to predict and control can be used for self-interested or even malicious purposes, while an enhanced understanding of how the human mind works might undermine people's beliefs in free will and personal responsibility.
It's hard to see how human beings can have a sense of freedom if they have genetic predispositions, conditioning from the environment, or both.
Similar criticisms have been leveled against behaviorist theories.
There are other limitations to theoretical explanations.
A theory can only explain certain aspects of human behavior.
Many theories claim to explain human nature as a whole, but only account for a small portion of human experience.
Advocates of a theory can dismiss the experience of individuals who fall outside of the theory's field of application because of this kind of bias.
Some aspects of the human mind, such as consciousness and creativity, can't be easily measured, quantified, or observed from an outside perspective.
If a theory attempts to address some of the less quantifiable aspects of psychology, it may not be susceptible to any kind of empirical verification.
Many psychodynamic and humanistic theories have been critiqued for being insufficient in their rigor.
Theories can contribute to promoting dangerous ideologies, as has been seen in psychology's history with respect to phrenology, eugenics, and other now-discredited ideas.
An overly pessimistic view of human nature might be presented by a theory, something Freudian psychoanalysis is often criticized for.
Any theory can be taken too far if it is accepted as a universal principle.
Theories will remain an essential part of psychology for the foreseeable future, just as they are essential for any natural or social science.
The key is to know that theories are always partial explanations, and that they can be used to enhance our understanding of the world.
Since its birth in 1879, psychology has grown like a tree.
Some of its branches have been trimmed over the years, but other branches have sprouted and flourished.
You should be aware of the wide variety of psychological specialties practiced in the twenty-first century now that you have reviewed the roots of psychology, its nineteenth- and twentieth-century history as well as its millennia of prehistory.
The Rapid Review section contains a comprehensive list of psychological domains.
You should have a basic idea of what to expect in the exam.
The AP Psychology exam tests your familiarity with psychology's history and a wide variety of its theories and domain, but also with individual psychologists who have made significant contributions to their fields.
The Rapid Review section has a list of important contributors.
Some examples of research include the method of introspection used by the structuralists and the conditioning experiments of the behaviorists.
We'll start with a discussion of the different types of research that psychologists use.
How each method works, when and why it is used, and its strengths and limitations will be reviewed.
It is important to distinguish between quantitative and qualitative research methods before looking at certain types of studies.
Quantitative research involves numerical data, while qualitative research does not.
Structured observations and surveys are examples of correlational studies in quantitative research.
naturalistic observations and some case studies are included in qualitative research.
Quantitative versus qualitative should be considered more of a spectrum than a simple division because some types of research mix both methods.
When psychologists want to make generalizations about behavior, quantitative research is used.
Quantitative methods can support or challenge psychological theories.
Quantitative studies have more objective data than qualitative studies.
Quantitative data can be analyzed to yield better generalizations.
Many quantitative studies can easily be duplicated.
Quantitative studies are limited because they don't take place in natural environments, so they only reflect what happens in more controlled settings.
Quantitative studies ignore data that can't be quantified.
This could leave out important information.
When researchers want to understand psychological phenomena from the perspective of research participants in a more natural setting, qualitative research is used.
It cannot make generalizations or test hypotheses, but qualitative research can explain how and why phenomena occur.
Data that is qualitative can be subjected to limited analysis.
The strength of qualitative research is that it gives a deeper look into phenomena within a specific context.
Qualitative research is limited because it does not allow robust generalizations, it is not properly replicable, and it can be quite costly and time consuming.
The validity and reliability of qualitative research are limited.
A broad category of quantitative research that includes surveys, some observational studies, and some case studies is called correlational studies.
correlational studies can determine correlations between variables but can't give conclusions about causality
A correlation is a relationship between variables that is expressed by the correlation coefficients.
The value of r is between -1 and +.
A positive correlation shows that two variables are related, meaning they follow the same pattern when one increases and the other decreases.
The correlation between height and weight is positive.
When one variable increases, the other decreases, it's a negative correlation.
People who are more physically active tend to weigh less.
The two variables vary completely independently of each other, and an r value of zero indicates no correlation.
The higher the absolute value of r, the stronger the relationship between the two variables.
correlational studies don't reveal anything about causality There is no way of knowing if A causes B or B causes A without conducting controlled experiments.
In situations in which controlled experiments are not feasible, correlational studies can be quite valuable.
They are easier to conduct than experiments.
Learning about the relationships between variables can still be useful.
Observational research methods are adapted to fit the goals and constraints of specific research projects.
observational studies seek to investigate phenomena as they actually occur in the real world, unlike experiments, in which researchers create an artificial and highly controlled set of circumstances.
naturalistic, structured, and participant are three broad types of observational studies.
naturalistic observation is used when researchers want to document behavior in a real-world setting Outside of a laboratory, the behavior can be observed in the natural environment.
It is a qualitative research method, though some steps can be taken to make it more quantitative, such as the use of larger sample sizes or coding.
naturalistic observation is conducted in a manner that is covert and undisclosed because the researcher can influence the way that people or nonhuman animals behave.
It may violate the privacy of individuals who are unaware that they are being watched if covert observation is done.
Structured observation is done in a laboratory setting.
The presence of researchers may be made discreet to minimize their influence on the situation.
Structured observations may have some impact on the behavior of the subjects being observed, but the impact is likely to be less extensive than other methods of research, such as interviews, which are based on self-reports of behavior.
Researchers try to achieve some level of consistency in describing their observations by using a system of coding, in which certain behaviors are classified into a number of different categories.
This allows for a more quantitative approach.
There are some additional concerns with coding.
Multiple coders may not be consistent in how they classify behaviors.
Inter-rater reliability is a measure of concordance between different classifications of the same phenomena.
Researchers are more confident in their conclusions if the inter-rater reliability is greater.
A third type of observation is participant observation, in which researchers deliberately enter into interactions with observed subjects, integrating themselves into the group being investigated.
This research method is more qualitative than naturalistic observation.
In which case researchers identify themselves as outsiders to the group who are interested in studying it, or covert, in which they hide their motives and try to join the group like any other member.
The same problems as other types of overt observation, such as possibly influencing the behavior of group members due to the presence of an outsider, are faced by overt participant observations.
The ethical concerns involved in deceiving a group, as well as the possibility that researchers may come to identify with the group being studied, can cause bias in their reporting.
Researchers may have to rely on memory if they can't take notes or electronically record interactions because of fear of blowing their cover with covert observation.
There is a possibility of recall bias, in which researchers emphasize more memorable details while neglecting what is less memorable.
Some of the limitations have already been noted.
The types of conclusions that can be drawn from observations are limited due to the ethical dilemma involved in hiding from or deceiving study subjects.
When they are quantitative, the conclusions of observations are at best correlational.
Observations allow researchers to gain a sense of the phenomena that they're investigating before they design and conduct controlled experiments.
The Hawthorne effect is a common limitation in observational studies.
The Hawthorne effect refers to the tendency of subjects to change their behavior simply because they are being watched.
The research tried to investigate the productivity of workers in response to changes in the work environment.
During the course of the research, employees increased their productivity, but these gains were short-lived.
The increased attention on the workers, as well as the novelty of being research participants, was the actual cause of the changes in productivity.
The Hawthorne effect is relevant when observations are made.
Two basic research strategies can be used by developmental psychologists to observe how cognitive, behavior, and other traits change over time.
Researchers follow the same group of people over time to see how they change with age.
A crosssectional study is conducted at a single point in time, comparing groups of different ages to arrive at conclusions about development.
Cross-sectional studies are much easier to conduct than longitudinal studies because they don't require years of commitment.
A case study is an in-depth and detailed examination of a specific case.
The case in psychological research can be a single person or a group of people.
Case studies typically involve less manipulation of the case and surrounding environment, reporting instead on a case as it exists in the real world.
Some case studies involve limited quantitative methods.
In clinical research, case studies can help researchers gain a better understanding of a psychological disorder by investigating all the ways in which the symptoms manifest in a particular patient and how they interact with the patient's environment and life circumstances.
Sigmund Freud and Carl Rogers used the results of their own clinical case studies to develop their distinctive theoretical approaches.
Case studies can give great insight into specific cases by examining them in depth, but they have a number of limitations.
Cases that are limited to a few subjects may not be representative, meaning that their results are difficult to generalize.
Because most case studies are qualitative, and even those with quantitative aspects often have ambiguity in their data, they can't produce robust generalizations about human or animal psychology, even when drawing upon the results of multiple case studies.
Case studies are subject to bias and can't generate conclusions about cause and effect since they lack experimental manipulation.
A survey is a list of questions that a group of people fill out.
In a wide variety of ways, surveys are administered.
Many surveys contain closed-ended questions with fixed responses, but some are open-ended, allowing respondents to provide their own answers.
Most surveys feature quantitative research methods.
When conducting survey research, psychologists can either draw on existing databases or construct their own surveys to fit their needs.
Many databases are available for researchers to use.
It can be more difficult to find the data a researcher needs, but using an existing dataset saves time and money.
Surveys can be used to study attitudes and beliefs that can't be observed directly.
Large numbers of participants allow for larger sample sizes and more generalizable results.
They carry high reliability because they are standardized.
Survey can be administered in a wide array of formats and is less expensive than other types of research.
There are limitations to survey research.
Survey can't be used to draw conclusions about cause and effect.
There is no guarantee that respondents will answer honestly.
When surveys are administered by a human being over the phone or in person, respondents may give answers that are socially desirable.
The response rate is a potential limitation.
A phenomenon known as nonresponse bias occurs when only a small percentage of subjects complete the survey.
There is a chance that the questions are written in a way that steers respondents to certain answers.
It is not always easy for researchers to avoid bias by carefully wording their questions.
Survey can be inflexible because they can't be changed during the data collection period.
Experiments are designed to test hypotheses.
A hypothesis is a statement about a relationship.
Sometimes an experiment can be used as a test of a theory.
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The controlled experiment is the gold standard in experimentation.
Controls and other precautions are used to ensure that the hypothesis can be tested in a controlled experiment.
Only controlled experiments are capable of supporting or challenging statements about cause and effect in correlational studies.
The level of control is more feasible in a laboratory setting.
The design of controlled experiments are discussed later in the chapter.
A field experiment is conducted outside of the lab in the real world.
There are limitations on how many variables can be controlled in field experiments, so researchers must rely on more advanced statistical techniques.
Field experiments can be used to deal with phenomena that can't be replicated in a lab.
The real-world setting is both an asset and a liability, since results are not obtained in an artificial environment like a lab, but there is a greater possibility of external factors confounding those results.
Field experiments conclusions are often more correlational than causality.
Natural experiments are also included in the controlled and field experiments.
A natural experiment or quasi-experiment does not involve direct manipulation of variables, but instead relies on natural variations in the variables of interest.
Natural experiments are useful in cases where it is impossible to manipulate the variables.
If a researcher wanted to study the effect of being orphan on cognitive development, he or she would have to rely on already-orphaned children, since creating new orphans is not an ethical option.
Natural experiments allow the study of phenomena that could not be investigated in a lab, but they are subject to the same limitations as field experiments.
Researchers can't directly manipulate any variables in quasi-experiments.
The ability to offer insights into cause and effect relationships is the greatest strength of experimentation.
Welldesigned field and natural experiments can offer some insight into causality, though with less confidence, though controlled experiments are particularly useful for this.
Experiments face a trade-off between confidence and generalizability, as can be seen in the contrast between controlled experiments and other types of experiments.
The more artificially controlled the circumstances, the more confident researchers can be about the results, but the less generalizable those results will be since the real world does not typically have such constraints.
Experiments are more difficult to conduct than other types of quantitative research.
The scientific method can enhance our knowledge by isolating, manipulating, and measuring specific aspects of experience.
The key to doing this is sound research design, the better the design of an experiment or other type of research, the more confident researchers can be about their conclusions.
The question will be explored in all its richness and depth in this section.
It's important to understand some basic terminology before we can comprehend good research design.
Experiments can provide evidence of causality between variables, as has been noted.
A researcher will identify one or more independent variables to be manipulated in the experiment and one or more dependent variables to be measured in the experiment.
Control variables are the constants in an experiment that should be held constant.
The risk of introducing variables other than the independent and dependent variables that influence experimental results is a consequence of a researcher failing to hold all other factors constant.
A researcher can conclude that any change measured in a dependent variable is caused by a manipulation made to an independent variable if they successfully control confounding factors.
These terms have distinct meanings that you need to keep straight for the exam.
The oneway nature of cause and effect is known as Cause - Effect.
The effects depend on causes.
dependent variables depend on independent variables
In this case, the dependent variable is the amount of sleep, while the independent variable is melatonin.
She needs to get a pool of research subjects and divide them into two groups to test this hypothesis.
Researchers need at least one control group and one experimental group in controlled experiments.
A control group is a reflection of circumstances without the influence of the independent variable.
A group of people who don't get melatonin might be a good control group.
An experimental group is exposed to the independent variable.
In this case, the researcher could create two groups, one that gets a smaller amount of melatonin and the other that gets a larger amount.
The absence or presence of the independent variable is the only difference between a control group and an experimental group.
The researcher can conclude that the change in the dependent variable was caused by changing the independent variable, if all other variables are controlled.
Human beings and nonhuman animals can be affected by many circumstances in an experimental setting so researchers take extra precautions to control the variables.
In the melatonin experiment, taking a pill before bed could cause the expectation of better sleep, and that expectation alone could cause a person to sleep longer.
The placebo effect is a phenomenon.
To control for this, researchers in experiments that involve the administration of drugs or other treatments will often supply control groups with a placebo, an inactive imitation of the treatment, such as a sugar pill.
If the sleep researcher gave her control group sugar pill placebos that looked exactly like the melatonin pills given to the experimental groups, she could be more confident that any increase in sleep time relative to the control group is caused by the melatonin.
The use of a single-blind design is required to control for the placebo effect.
Research participants don't know if they are in a control group or an experimental group in a single-blind experiment.
Everyone in a single-blind experiment believes they are being treated.
Double-blind research takes this to another level.
In a double-blind experiment, neither the participants nor the researchers know who is assigned to which group.
The researchers can't treat control group members differently from experimental group members because of this.
The control and experimental groups' knowledge is kept hidden until the data is collected and ready for analysis.
The gold standard for melatonin research is a double-blind setup.
There are other difficulties inherent in research on human subjects in addition to the social expectations that are controlled through double-blind design.
The experimental groups are supposed to be the same as the control groups.
Most of the time, these groups will be composed of distinct individuals who could vary widely as a result of differences in life experiences.
True control of the variables would require testing the same individuals both with and without the independent variable.
Random assignment is one of the techniques used by researchers to ensure as much similarity as possible between control and experimental groups.
Psychologists try to make general conclusions about large populations, sometimes as large as the entire human species, but research can only involve a small subset of individuals.
Researchers use elements of randomness in a variety of ways to make their research results more robust.
Random sampling is used to ensure that a sample is representative of the larger population.
A set of individuals with a range of characteristics that mirror the diversity found within the population is more likely to be created by a researcher.
Everyone in the population should have an equal chance of being selected in order to provide the best chance of a sample being representative.
Even if the sample is initially selected this way, there's no guarantee that the people who actually respond to the survey will be representative.
Because participation in experiments tends to be more demanding, achieving representativeness can be a challenge.
In experimental design, randomness is used to produce more robust results.
Random assignment is used when determining the membership of control and experimental groups, giving everyone in the pool of participants an equal chance of belonging to any particular group.
There is a good chance that there are no systematic differences between the experimental and control groups if the sample is large.
Random assignment reduces the chance of introducing variables.
The term "validity" has a number of different meanings in psychology, but two are particularly relevant in the context of research design.
The extent to which the experiment investigates what it is supposed to do is called internal validity.
The only significant differences between the control and experimental groups are the differences in the independent variable.
Internal validity will be affected by the presence of one or more variables.
External validity is a measure of how true to life or generalizable the results of a study are.
If an experiment has high external validity, it shows how things work in the real world.
The impact of research design on internal validity is clear.
The tendency for experimental participants to change their behavior to fit what they believe to be the purpose of the experiment can threaten internal validity.
Techniques like single-blind or double-blind design and placebos can be used to reduce demand characteristics.
The observer-expectancy effect, in which experimenters communicate their expectations of what the results will be and thereby influence the behavior of participants, is a threat to internal validity.
If the experimenters don't know what to expect from any given participant, then they have no expectations of results that they could communicate.
Researchers need to make sure that there are no significant differences between control and experimental groups in their experiments.
The only differences between groups are the differences in the independent variable.
Random assignment can make this result more likely.
In different ways, external validity is influenced by research design.
If a sample is representative, results are more generalizable.
External validity can be reduced by experimental conditions that are too far away from reality.
There is a potential conflict with the measures taken to improve internal validity.
It is possible to make the experiment less true to life if you increase the degree of control over the experimental circumstances.
Researchers need to find a balance between making experiments feel natural and controlling extraneous variables.
Different types of research find the balance different.
phenomena that have been well-established in laboratory settings don't always figure prominently in our day-to-day lives due to the fact that controlled experiments are often more internally valid than external valid.
naturalistic observations, field experiments, natural experiments, and correlational research all have low internal validity and high external validity.
It is difficult to know what is causing changes in any measured quantities, even though results observed in these studies can be generalized to the real world.
There are other types of validity that are relevant to psychology.
There are more types of validity in cognitive psychology.
Experiments and correlational studies are types of quantitative research because they rely on numerical data.
Natural quantities like length, mass, temperature, and concentration are easy to measure in physics and chemistry.
When designing and conducting research, psychological researchers must operationalize their variables.
An operational definition is a description of how a variable will be measured.
Operationalization involves taking an abstract or vague concept and finding some measurable quantity that serves as an indirect indication of it.
The results of a standardized IQ test are used to define the intelligence we call it.
IQ scores are not the same as intelligence, but they are an objective quantity that reflects the underlying quality of intelligence.
It is generally acceptable to use IQ score as an operational definition of intelligence, since a high level of intelligence causes high performance on IQ tests.
correlational and experimental research in psychology can be done because of operational definitions.
Stanley Smith Stevens, a psychologist, first identified the type of measurement introduced by an operational definition.
In nominal measurement, qualities are assigned numerical values.
For instance, gender could be designated as (1) for female, (2) for male, and (3) for other, with these quantities having no real meaning except as a way of distinguishing between categories.
A ranking order might be found in a list of preferences.
The scale has a fixed meaning for differences between numerical values.
If you're comparing 10 degrees to 20 degrees or 80 degrees to 90 degrees, the difference of 10 degrees always means the same thing.
Intervals and ratios between numbers are important in ratio measurement.
It is not true for an interval scale like Fahrenheit that 200deg is twice as hot as 100deg.
The zero assigned to a non-arbitrary value means that the complete absence of heat is defined as 0deg.
Interval and ratio scales allow for the most robust conclusions, but any type of measurement can help to quantify data and allow for statistical analysis of research results.
The subject of the next section is how statistical analyses are used in psychology.
A lot of raw numerical data can be found in experiments and other quantitative studies.
Statistics are used to make sense of the data.
Descriptive and inferential statistics are used in psychology.
Each involves distinctive techniques that are used for specific purposes.
Descriptive statistics describe the data.
They don't say much about whether a research conclusion is valid or a hypothesis is confirmed, but they do say a lot about what the raw data looks like.
Descriptive statistics are used by psychologists to answer questions and give summaries of other patterns in their data.
The exam expects you to know how to apply a few specific descriptive statistical techniques.
Inferential statistics are concerned with larger generalizations that can be made from the data.
approximations of parameters and tests of hypotheses are two types of inferences that are used for the AP Psychology exam.
Samplings were considered subsets of populations used for research purposes earlier in the chapter.
The characteristics of populations are referred to as parameters and the characteristics of samples are referred to as statistics.
It is possible to distinguish between average height and average height as a statistics of a sample, which can be calculated using only the data collected in a study.
The statistics may or may not be a good indication of the parameters.
One kind of inferential statistics concerns how to generalize from the statistics of samples to the populations.
The range of likely values for a parameters is offered by measures such as confidence intervals, which are used in psychology.
The range of values in which the true parameter would fall in 95 out of 100 cases is the 95% confidence interval for a particular variable.
hypothesis testing is a major technique inferential statistics.
Experiments and other types of research are ways of testing hypotheses.
In the following example, a simple experiment with a single independent variable and a single dependent variable, along with one control group and one experimental group, is assumed.
There is no relationship between the dependent variable and the independent variable according to a null hypothesis formulated by a researcher.
An alternative hypothesis states that there is a particular kind of relationship between the two variables, such as that the independent variable exerts a influence on the dependent variable.
The researcher will use the results of the control group and experimental group to calculate a p-value that shows the probability that the null hypothesis is true.
When the results of an experiment seem to indicate a relationship between a pair of variables, the p - value is the probability that this result occurred due to random chance.
Lower values of p indicate a greater probability of a relationship because this is a measure of how likely it is that there's no relationship between the variables.
If the calculated p - value is below a set significance level, the null hypothesis is rejected and the alternative hypothesis is confirmed.
The results are said to be statistically significant when this occurs.
You may see references to types of error in inferential statistics on the exam.
A false positive is the improper rejection of a correct null hypothesis.
It's assuming that there's a relationship between the variables that isn't there.
The type I error can be reduced by using a stricter significance level.
The type II error, or a false negative, is the improper affirmation of an incorrect null hypothesis.
It's assuming that there isn't a relationship between the variables.
Descriptive statistics describe patterns in data.
The AP Psychology exam expects you to know how to work with graphs, calculate measures of central tendency, and calculate or estimate measures of dispersion.
You already know that graphs are visual representations of data.
The AP Psychology exam requires you to be able to interpret the data presented in graphs and to make simple graphs from it.
Line graphs, bar graphs, and scatterplots are the most common types of graphs you'll see in AP Psychology.
Line graphs show the relationship between two variables.
The dependent variable is plotted on the vertical y- axis while the independent variable is plotted on the horizontal x- axis.
The data points are connected by a line.
A line with a positive slope indicates a positive correlation between variables, while a line with a negative slope indicates a negative correlation.
There is no correlation with a flat line with a slope of zero.
The heights and lengths of the rectangles are used in bar graphs.
Similar to bar graphs are histograms, which are representations of the data points.
In a histogram of test scores, the highest bar represents the mode, while two bars with the same height show the number of students who received the scores.
Scatterplots represent the data points collected in a study.
Unlike line graphs, where all the points are connected, scatterplots represent each data point with a symbol.
A line that passes through the middle of the data points is known as a line of best fit.
A line of best fit is similar to a line graph.
You should be able to interpret learning graphs for the exam.
Learning has more on these graphs.
The middle of a distribution of data is described by measures of central tendency.
There are three things to know for the exam.
The average is the sum of the data divided by the number of points.
When the data is arranged in increasing or decreasing order, the median is the value in the middle.
The mode is the most frequent value.
Consider the following five data points, which could be measures of a single dependent variable like number of words recalled or seconds required to respond to a prompt: 4, 1, 7, 2, 1.
When the data are arranged in order, the median is 2, the number that appears in the middle.
The mode is 1 because it appears twice.
The mean, median, and mode all correspond to the same value in some distributions of data.
When data contains a lot of outliers, points that have extreme values relative to the rest of the data may be widely diverging.
In the United States, there are a relatively small number of multimillionaires and billionaires that raise the mean household income far higher than the median.
The median is often used as a better indication of where the "true middle" is, in this case, it would give a better idea of who belongs to the middle class.
When the data set is heavily skewed, the median is often used instead of the mean to analyze it.
The mode is the least used measure of central tendency, but is helpful in describing nominal data that falls into non-ordered categories.
For example, psychologists might collect data on hair color, presence or absence of a certain gene, or participants' selection from several options.
Descriptive statistics that describe the distribution of data, or how spread out it is, are called measures of dispersion.
Range, variance, and standard deviation are some of the measures of dispersion.
The range is the difference between the highest and lowest values in the data.
The highest value was 7 and the lowest was 1, so the range would be: 7 - 1 - 6.
The range gives a sense of the entire spectrum of the data, but it doesn't reveal anything about how points are dispersed within that spectrum.
The number of points minus one is used to divide the variance by the difference between the data points and the mean.
The mean for the set was 3.
The data has a variance of 6.5.
The square root of the variance is the standard deviation.
The average difference between any given data point and the mean is offered.
The more spread out the data points are, the higher the standard deviation is.
The standard deviation is the most commonly used measure of dispersion and is the one that most often appears on the AP Psychology exam.
Many questionable experiments and studies were conducted on human subjects in the 19th and 20th century.
Hundreds of African American men with syphilis were allowed to go undetected and be treated in the hopes of studying the progression of the disease.
The U.S. government commissioned a report in the late 1970s about morally suspect research.
Human subjects research must respect individuals and their ability to act freely.
Before conducting research, researchers should always stress that participation is voluntary.
Children, the mentally disabled, and the incarcerated should receive additional protections.
Researchers must not harm their subjects.
They have to maximize benefits for research participants.
Net social benefits should be provided by research in some way.
The burdens and benefits of research need to be distributed fairly.
Researchers should take care not to rely too much on disadvantaged populations as research subjects, as the burdens involved in research participation should be equal for all participants.
Benefits should be distributed equally among participants and larger social benefits that result from the research should be widely available.
Equal distribution can only be done for compelling reasons.
Legislation and other guidelines on human subjects research were inspired by these three principles.
The ethical practices discussed below are based on one or more of the principles.
The requirement for informed consent in human subjects research was one of the suggestions.
Information about the research prior to participation is called informed consent.
The purpose of the research, the procedure it involves, expected benefits and risks of participation, and any other factors that may influence an individual's desire to participate should be included in these details.
Prospective participants should be informed of their rights, including the right to leave the study at any time, and be given the opportunity to ask and receive answers to questions.
The principle of respect for persons leads to the practice of informed consent, which allows research to be more voluntary if you know what you're doing.
It is possible that fully informed consent can invalidate results in some cases.
In the experiment described earlier in this chapter testing the effect of melatonin on sleep duration, it was shown to the subjects whether the pills they take contain melatonin or a placebo could have an effect on how long they sleep.
When absolutely necessary for the experiment, researchers are allowed to temporarily deceive subjects.
In such cases, researchers must still provide as much accurate information as they can prior to the study, must still allow participants to leave the study when they want, and must debrief participants after the study has concluded.
The purpose of the study, the results of the study, and any other relevant information should be explained in this debriefing.
The principle of respect for persons requires respect for personal privacy as well.
Confidentiality should be maintained for all research participants, with access to personally-identifying information restricted as much as possible to conduct the research.
Governments and other institutions impose and enforce a variety of regulations on human subject research.
In the United States, the Department of Health and Human Services and its Office for Human Research Protections oversee a system of institutional review boards.
IRBs are committees that approve or reject proposals for human subjects research projects.
IRBs apply the principles outlined in the report to conduct research ethically.
Human subjects research that is not approved by the IRB is illegal in the U.S.
Nonhuman animals can't sign informed consent forms, so there are different guidelines for research.
When working with animals, researchers face fewer restrictions, but still face ethical and legal guidelines.
College and universities have laboratory animal care committees that review proposed animal research to make sure that the animals are treated with respect and that there is no pain.
Alternative research designs can be used to avoid potentially painful procedures.
Guidelines for the proper use of animals in research have been published by the American Psychological Association and the Society for Neuroscience.
The history of psychology is full of questionable research studies.
Researchers who tried anything like this today would never get approval from the IRB.
The table summarizes a few of the most noteworthy psychological studies that could never be done now.
If you want to practice for an exam on this topic, go to Rapid Review and Practice.