Research Methods Chapter 2

How Do Psychologists Develop New Knowledge? Psychologists, like researchers in all other sciences, use the scientific method to test their ideas empirically.

How Do Psychologists Develop New Knowledge? Empirical investigation – “experienced based” An approach to research that relies on sensory experience and observation as research data. Scientific method – A five-step process for empirical investigation of a hypothesis under conditions designed to control biases and subjective judgments.

We call these explanations, THEORIES! A main goal of psychological science is to develop scientific explanations for behavior and mental processes. We call these explanations, THEORIES! To scientists theory means the power to explain the facts and its ability to be tested objectively.

The Five Steps of the Scientific Method Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results

Developing a hypothesis Hypothesis – A statement predicting the outcome of a scientific study Operational definitions – Exact procedures used in establishing experimental conditions and measurement of results

Performing a controlled test Independent variable – The variable manipulated by the experimenter Random presentation – Using chance alone to determine the order in which the stimulus is presented

Gathering objective data Data – Information gathered by researcher and used to test a hypothesis Dependent variable – The measured outcome of a study; the responses of participants in a study

Analyzing the results Based on statistical analyses of results, the hypothesis is accepted or rejected

Publishing, criticizing, and replicating the results Researchers must find out whether their work can withstand the scrutiny of the scientific community. How is this done?

Psychological Research What are confounding and extraneous variables? How do they effect the scientific method? What is “random assignment” and how is it used in experiments?

Non-Experimental Methods There are some situations in which experiments cannot be done for ethical reasons. Non-Experimental methods can yield useful data, but they are just not “true” experiments because they are missing a component of the experiment, usually in the areas of the controls. Ex Post Facto: subjects are chosen on the basis of a preexisting condition. Example?

Types of Psychological Research In experiments, the researcher controls all the conditions and directly manipulates the conditions Non-experimental methods include: Correlational studies Surveys Naturalistic observation Longitudinal studies Cross-sectional studies Cohort-sequential studies

Correlation Studies Are used to see a relationship (correlation) btw two variables. Smoking and lung cancer. CORRELATION DOES NOT NECESSARILY MEAN CAUSATION!

Continued… The degree of correlation is normally expressed as a number. R= correlation coefficient Range from negative # (-1.0: + 1.0) If variables have no relationship= zero correlation Relationship in which they vary in the same direction = positive correlation (+0.4) A correlation can show a strong relationship even when its negative.

Surveys Not a true experiment, but if conducted correctly can yield useful data. Researchers need to make sure the questions are not skewed or bias. Participants tend to not take surveys seriously, due to this surveys tend to yield incorrect results.

Naturalistic Observation Subjects are observed in their natural environment. Subjects should NOT know they are being observed, this way the behavior being observed is actual behavior in their natural state. Children on the playground, animals in the wild.

Longitudinal Studies One group of subjects is followed/observed for an extended period of time. Benefits: same subject group Negatives: Time and expense Example: Following special needs children for their first 15 years of their lives.

Cross-Sectional Studies Examines a representative cross section of the population and tests/surveys these subjects at one specific time. Will yield data similar to longitudinal studies, but the data won’t be as accurate.

Cohort-Sequential Studies Similar to Cross-Sectional Here, researchers take a cross section of the population and then follows each cohort or group for a short period of time. This study takes less time than longitudinal studies and yields more accurate data than a cross sectional study.

Sources of Bias Bias could affect the way an experimenter designs a study, collects data, or interprets results Sources of bias include: Personal bias Expectancy bias

Personal Bias Involves and individuals beliefs, preferences, assumptions, or prejudices. This bias can cause scientists to notice only evidence confirming their hypotheses and to ignore contrary data

Expectancy Bias This bias effects observations when observers expect and LOOK for certain outcomes. Bias not only leads to erroneous conclusions, but it can also be expensive.

How to “control” a Bias Double blind studies attempt to control bias. This strategy ensures that the experimenters will not inadvertently treat the experimental group differently from the control group, so that neither group will have any idea about the expected response. Placebo: Researchers must also attempt to control confounding variables

Ethics in Research In order to make sure research is conducted in an appropriate manner, guidelines are put in place by the APA, IRB, and IACUC. These boards review and approve all research and make sure the experiments comply with local, state, national requirements. Deception Debriefing Animal research

Deception Participants should be advised about what challenges they will face and give them an opportunity to drop out. In other situations, participations must be informed of deception as soon as possible with out compromising the study's research goals. They must be debriefed to make sure there is not lasting ill effects.

Animal Studies Psychologists, most support the use of animal research. But, they do not support or approve of animal studies that cause harm, pain, or result in death of their subjects.

Questions Science Cannot Answer The scientific method is not appropriate for answering questions that cannot be put to an objective, empirical test Ethics Morality Religious beliefs Preferences

How Do We Make Sense of the Data? Researchers use statistics for two major purposes: (1) descriptively to characterize measurements made on groups or individuals and (2) inferentially to judge whether these measurements are the result of chance