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Copyright © Allyn & Bacon 2007 How Do Psychologists Develop New Knowledge? Psychologists, like researchers in all other sciences, use the scientific method to test their ideas empirically

Copyright © Allyn & Bacon 2007 Empirical investigation – An approach to research that relies on sensory experience and observation as research data How Do Psychologists Develop New Knowledge? Scientific method – A five-step process for empirical investigation of a hypothesis under conditions designed to control biases and subjective judgments

Copyright © Allyn & Bacon 2007 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

Copyright © Allyn & Bacon 2007 Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results Hypothesis – A statement predicting the outcome of a scientific study Operational definitions – Exact procedures used in establishing experimental conditions and measurement of results The Five Steps of the Scientific Method

Copyright © Allyn & Bacon 2007 Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results Independent variable – The variable manipulated by the experimenter Random presentation – Using chance alone to determine the order in which the stimulus is presented The Five Steps of the Scientific Method

Copyright © Allyn & Bacon 2007 Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results 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 The Five Steps of the Scientific Method

Copyright © Allyn & Bacon 2007 Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results Based on statistical analyses of results, the hypothesis is accepted or rejected The Five Steps of the Scientific Method

Copyright © Allyn & Bacon 2007 Developing a hypothesis Performing a controlled test Gathering objective data Analyzing the results Publishing, criticizing, and replicating the results The Five Steps of the Scientific Method Researchers must find out whether their work can withstand the scrutiny of the scientific community

Copyright © Allyn & Bacon 2007 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

Correlational Research Determines relationships between variables Shows patterns, not causation. Great predictors of future outcomes Strength and direction of relationship is important Copyright © Allyn & Bacon 2007

Correlations: A relationship between Two Variables Correlation– A relationship between two variables, in which changes in one variable are reflected in changes in the other variable

Surveys Series of questions asked to obtain large amount of data on a topic Inexpensive, much data collected, access to large groups MUST use representative samples Representative sample obtained randomly from the larger population being studied Courtesy Bias: subject trying to please Must word questions to prohibit prejudice; skew results Copyright © Allyn & Bacon 2007

Naturalistic Observation Subjects observed in their natural environment Examples: child rearing methods, shopping habits, public displays of affection Observer Effect: subjects not behave normally if they know they are being watched Observer Bias: observer reads into behavior or sees only what they want to Copyright © Allyn & Bacon 2007

Naturalistic Observation Participant Observation: researcher becomes member of the group being studies Blind Observers: individuals who watch, observe and document everything without knowing the specifics of the study Copyright © Allyn & Bacon 2007

Case Studies One subject is studied in depth in order to revealing universal principles Provide direction for further study Phineas Gage: first case study Copyright © Allyn & Bacon 2007

Longitudinal Studies Used to study long range effects on something Pros: Accurate date, use same group Cons: Time consuming, expensive Example: Effects of divorce on kids before the age of 10 years old. Copyright © Allyn & Bacon 2007

Cross Sectional Studies Survey and test a cross section (several age groups) of the sample population. Study and test all at the same time. Don’t follow or study for any time period. Simply survey and test. Copyright © Allyn & Bacon 2007

Sources of Bias Sources of bias include: Personal bias: researcher allows personal beliefs to affect outcome of the study Expectancy bias: researcher allows for their expectations to affect the outcome of study

Bias Bias could affect the way an experimenter designs a study, collects data, or interprets results Double blind studies attempt to control bias Researchers must also attempt to control confounding variables Copyright © Allyn & Bacon 2007

Making Inferences with inferential statistics Inferential statistics are used to assess whether the results of a study are reliable or whether they might be simply the result of chance Sampling Random sample: subjects selected by chance (without bias) Representative sample: reflects variables in which the researcher is interested (age, gender, income level, ethnicity, geographic distribution) Statistical significance: results less than 5 in 100 that the results are due to chance.

Copyright © Allyn & Bacon 2007 Ethics in Research Deception Debriefing Animal research

Copyright © Allyn & Bacon 2007 End of Chapter 2