PSYC 100: Psychological Science

Introduction

• The main purpose of research done by psychologists is to understand people and improve the quality of human lives.

  • Research can either be basic or applied.

    • Basic research is primarily concerned with acquiring a better knowledge of how different psychological processes occur.

    • Applied research is concerned with testing and finding solutions to problems.

  • Results of research are reported in articles posted in scientific journals.

    • There are a wide variety of psychological research journals, typically separated by the type of psychology the journal is focused on.

Psychologists Use the Scientific Method to Guide Their Research

• All scientists are engaged in the basic processes of collecting data and drawing conclusions about those data.

• The scientific method has a certain set of stipulations.

  • Procedures used must be objective.

    • The data is placed under scrutiny of other scientists and even the general public to ensure that data is free from personal bias.

  • Research must be able to be replicated.

Laws and Theories as Organizing Principles

• A goal of research is to organize information into meaningful statements that can be applied in many situations.

  • Law: principles that are so general as to apply to all situations in a given domain of inquiry

    • very general and their validity has already been well established.

    • rarely subjected to scientific test

  • Theory: an integrated set of principles that explains and predicts many, but not all, observed relationships within a given domain of inquiry.

    • Theories have four important characteristics.

      • Are general

      • Are parsimonious

      • Provide ideas for future research

      • Are falsifiable

    • no single theory is able to account for all behavior in all cases

The Research Hypothesis

• The basis for research since theories are usually too broad to be tested in a single experiment is a research hypothesis.

  • States the existence of a relationship between the variables of interest and the specific direction of that relationship.

• Conceptual Variables: the abstract ideas that form the basis of research hypotheses.

• The first step in testing a research hypothesis is turning the conceptual variables into measured variables.

  • Psychologists often use the term operational definition to refer to a precise statement of how a conceptual variable is turned into a measured variable.

    • Specific definitions mean there is less danger that collected data will be misunderstood by others and that specific definitions will enable future researchers to replicate the research.

Conducting Ethical Research

• Concerns over ethics is a major part of research,

  • Psychological research may cause stress, harm, or inconvenience for participants.

• Researchers must follow the established ethical codes developed by scientific organizations and federal governments in order for their research to be considered ethical.

  • The most direct ethical concern is to prevent harm to the research participants.

  • Participants must be guaranteed to have free choice regarding their desire to participate in research.

  • The privacy of participants must also be protected.

  • Deception can be used in research, but researchers must also explicitly consider how their research can be conducted without the use of deception.

Ensuring that Research is Ethical

• Making decisions about the ethics of research involves weighing the costs and benefits of conducting vs. not conducting a given research project.

  • cost-benefit analysis; if the potential costs seem to outweigh the potential benefits, then the research should not proceed.

• Institutional Review Board (IRB): a committee of at least 5 members whose goal it is to determine the cost-benefit ratio of research conducted within an institution.

  • must approve the procedures of all research conducted before it can begin.

• Participant(s) must be given informed consent before research can proceed.

• Participants must also be fully debriefed immediately after participation.

  • Debriefing is designed to fully explain the purposes and procedures of the research and remove any harmful aftereffects of participation.

Research with Animals

• Most psychological research that uses animals tends to use rats, mice, and birds.

  • There are also a strict set of guidelines when dealing with animals as research participants.

Key Points

• Psychologists use the scientific method to generate, accumulate, and report scientific knowledge.

• Basic research, which answers questions about behavior, and applied research, which finds solutions to everyday problems, inform each other and work together to advance science.

• Research reports describing scientific studies are published in scientific journals so that other scientists and laypersons may review the empirical findings.

• Organizing principles, including laws, theories and research hypotheses, give structure and uniformity to scientific methods.

• Concerns for conducting ethical research are paramount. Researchers assure that participants are given free choice to participate and that their privacy is protected. Informed consent and debriefing help provide humane treatment of participants.

• A cost-benefit analysis is used to determine what research should and should not be allowed to proceed.

Psychologists use Descriptive, Correlational, and Experimental Research Designs to Understand Behavior

• Research Design: the specific method a researcher uses to collect, analyze, and interpret data.

• Characteristics of the Three Research Designs

Descriptive Research: Assessing the Current State of Affairs

• Descriptive research gathers data in 3 different ways.

• Case Studies: descriptive records of one or more individual’s experiences and behaviors

  • usually conducted on individuals who have unusual or abnormal experiences or characteristics or who find themselves in particularly difficult or stressful situations.

• Data from descriptive research projects tend to come from surveys.

  • a measure administered through either an interview or a written questionnaire to get an idea of the beliefs or behaviors of a sample of people of interest

• Naturalistic Observation: based on the observation of everyday events.

• Results of descriptive research projects are analyzed by using descriptive statistics.

  • Numbers that summarize the distribution of scores on a measured variable.

  • Normal distribution = bell-shaped

• Distribution can be described in terms of its central tendency.

  • arithmetic mean is the most common used measure

  • if there are extreme outliers, median is used as an alternative measure

  • final measure of central tendency is mode.

• Descriptive statistics convey information about how the scores of the variable are spread around the central tendency.

  • dispersion

    • a simple measure of dispersion is the standard deviation, which is the range of variables

• An advantage of descriptive research is that it attempts to capture the complexity of everyday behavior.

• A disadvantage of descriptive research is that it is usually limited to static pictures of what is currently happening.

• Case studies provide detailed information about a single person or a small group of people.

• Surveys capture the thoughts or reported behaviors of a large population of people

• Naturalistic observation objectively records the behavior of people or animals as it occurs naturally.

Correlational Research: Seeking Relationships Among Variables

• Correlational research involves the measurement of two or more relevant variables and an assessment of the relationship between or among those variables.

  • Predictor variable and outcome variable

• A scatter plot can be used to organize the data.

  • a visual image of the relationship between two variables

  • positive linear: when the line indicates that individuals who have above-average values for one variable also tend to have above-average values for the other variable

  • negative linear: when the line indicates when above-average values for one variable tend to be associated with below-average values for the other variable

  • nonlinear relationships occur when the data is not seen to be in a straight line

• Pearson correlation coefficient: the most common statistical measure of the strength of linear relationships among variables.

  • symbolized by r.

  • positive values of r indicate that the relationship is positive linear, and negative values of r indicate negative linear relationships.

• Multiple regression: a statistical technique based on correlation coefficients among variables that allows predicting a single outcome variable from more than one predictor variable

• Correlational research designs cannot be used to draw conclusions about the casual relationships among the measured variables.

• Common-casual variable: a variable that is not part of the research hypothesis but that causes both the predictor and the outcome variable and thus produces the observed correlation between them.

  • aka third variable

  • when the predictor and outcome variables can be explained away by a common-casual variable, the relationship then becomes spurious.

• Due to common-casual variables, we are left with the understanding that correlation does not equal causation.

Experimental Research: Understanding the Causes of Behavior

• The goal of experimental research design is to provide more definitive conclusions about the casual relationships among the variables in the research hypothesis.

  • uses independent variable(s) and the dependent variable.

• Experimental designs guarantee that the independent variable occurs prior to the measurement of the dependent variable, and the influence of common-casual variables is controlled.

• The most common method of creating equivalence among the experimental conditions is through random assignment.

• The limitations of experiments are that they are conducted in laboratory settings instead of everyday settings, and that more key social variables cannot be experimentally manipulated.

Key Points

• Descriptive, correlational, and experimental research designs are used to collect and analyze data.

• Descriptive designs include case studies, surveys, and naturalistic observation. The Goal of these designs is to get a picture of the current thoughts, feelings, or behaviors in a given group of people. Descriptive research is summarized using descriptive statistics.

• Correlational research designs measure two or more relevant variables and assess a relationship between or among them. The variables may be presented on a scatter plot to visually show the relationships. The Pearson Correlation Coefficient ( r ) is a measure of the strength of linear relationship between two variables.

• Common-casual variables may cause both the predictor and outcome variable in a correlational design, producing a spurious relationship. The possibility of common-casual variables makes it impossible to draw casual conclusions from correlational research designs.

• Experimental research involves the manipulation of an independent variable and the measurement of a dependent variable. Random assignment to conditions is normally used to create initial equivalence between the groups, allowing researchers to draw casual conclusions.

You Can Be an Informed Consumer of Psychological Research

• Good research is valid research.

  • However, there are many threats to the validity of research, which may sometimes lead to unwarranted conclusions.

• There are four major types of threats to the validity of research

  • Threats to construct validity: although it is claimed that the measured variables measure the conceptual variables of interest, they actually may not

    • a requirement to construct validity is that the measure must be reliable

  • Threats to statistical conclusion validity: conclusions regarding the research may be incorrect because no statistical tests were made or because the statistical tests were incorrectly interpreted.

    • tests must show statistical significance

  • Threats to internal validity: although it is claimed that the independent variable caused the dependent variable, the dependent variable actually may have been caused by a confounding variable

    • mostly affects experimental designs

    • experimenter bias: a situation in which the experimenter subtle treats the research participants in the various experimental conditions differently, resulting in an invalid confirmation of the research hypothesis.

      • to avoid this, researchers usually partake in the double-blind experiment

  • Threats to external validity: although it is claimed that the results are more general, the observed effects may actually only be found under limited conditions or for specific groups of people

    • Generalization: the extent to which relationships among conceptual variables can be demonstrated in a wide variety of people and a wide variety of manipulated or measured variables

      • Unless the researcher has a specific reason to believe that the generalization will not hold, it is appropriate to assume that a result in one population will generalize to other populations.

• Any single test of a research hypothesis will always be limited in terms of what it can show, thus any important advances are never the result from a single research project.

• Meta-analysis is used to summarize replications of research findings.

  • specifies inclusion criteria that indicate exactly which studies will or will not be included in the analysis

  • systematically searches for all studies that meet the inclusion criteria

  • provides an objective measure of the strength of observed relationships

Key Points

• Research is said to be valid when the conclusions drawn by the researcher are legitimate. All research has the potential to be invalid, thus, no research ever “proves” a theory or research hypothesis.

• Construct validity, statistical conclusion validity, internal validity, and external validity are all types of validity that people who read an interpret research need to be aware of.

• Construct validity refers to the assurance that inferences about statistical significance are appropriate.

• Internal validity refers to the assurance that the independent variable has caused the dependent variable. Internal validity is greater when confounding variables are reduced or eliminated.

• External validity is greater when effects can be replicated across different manipulations, measures, and populations. Scientists use meta-analyses to better understand the external validity of research.