Research Methodology

What Is Scientific Inquiry?

What Are the Types of Studies in Psychological Research?

More on Data-Collection Methods in Psychological Science

Ethics

Miscellaneous

Scientific Inquiry: Four goals

Four goals of scientific inquiry:

Description (what happens):

Prediction (when it happens):

Causal Control (what causes it to happen):

Explanation (why it happens):

Scientific Inquiry: Some terminology

Theory: An organized set of principles that describes, predicts, and explains some phenomenon.

Hypothesis: A specific testable prediction, often derived from a theory

Variable: Any dimension that varies across individuals, time, or place;

Operational definition: Exactly specifies and quantifies the variables used in a scientific investigation

Fact: Objective statement that describes a particular behavior that is reliably and directly observed

Scientific Inquiry: Normal course of a scientific investigation

Good Research Requires Valid, Reliable, and Accurate Data

Validity Is your measuring tool (your “scale”) measuring

what you think it is measuring? Reliability

If something is stable over time, and you measure it repeatedly, do you get the same answer repeatedly?

Accuracy Is your measurement free from random error? Is your measurement free from systematic error (or

bias)?

Types of Studies in Psychological Research: Descriptive

• Case studies A type of research that involves making in-depth

observations of individual persons.

Naturalistic observations The observation of behavior as it occurs naturally in

real-world settings

Archival Records A form of research that relies on existing records of

past behavior.

Archival research (Panel 1)

Archival research (Panel 2)

Archival research (Panel 3)

Types of Studies in Psychological Research: Correlational •Self-Report

A method of observation that involves asking people to describe their own thoughts, feelings, or behavior.

Surveys One type of self-report method

Involves interviewing or giving questionnaires to a large number of people.

When surveys target at least two different variables, a statistic called a correlation is often used to summarize the relationship between the variables.

Once the relationship between two variables is known, it allows an experimenter to predict the value of one variable from the other variable without needing to measure both variables in the particular population of interest

Correlation Correlation

A statistical measure of how closely two variables are associated; usually denoted by r

Correlations can range from -1.0 to +1.0 –1.0 and +1.0 correlations are very strong

Here are some examples of real world correlations Gender and arm strength, r=.55 Employment interviews and job success, r=.20 Taking antihistamines and reduced runny nose, r=.11 Taking aspirin and reduced risk of death from heart attack,

r=.02 When r = 0, no relationship exists between the two variables Scatterplots are often used to convey the relationship between

two variables

Positive correlation

Negative correlation

Zero correlation

Some limitations on correlations

Directionality problem Third variable problem

Correlation does not prove causation.

Types of Studies in Psychological Research: Experiments

A type of research in which the investigator varies some factors, keeps others constant (control), and measures the effects on randomly sampled and randomly assigned subjects. Demonstrates causation.

Elements of the experimental approach

Independent Variable (IV) Any variable that the researcher manipulates in an

experiment The proposed cause of change in the dependent

variable Dependent Variable (DV)

A variable that is being measured in an experiment Proposed to be affected by the independent variable

Treatment vs. control groups (or conditions) The control group is not treated in an unusual way The treatment group is treated differently than usual

More elements of the experimental approach

Random assignment One way in which the experimenter controls (i.e., eliminates)

differences between the two groups before the independent variable is applied.

Logic of an experiment The IV is the only thing that the experimenter knowingly

varies across conditions If the DV also varies across the conditions, the IV must have

caused that difference because there was nothing else that could have caused the difference.

Confound A variable in an experiment – besides the IV – that also

unintentionally varies across the groups This undercuts the experimenter’s ability to state

unambiguously that changes in the IV caused the changes in the DV

More on Data-Collection Methods of Psychological Science: Response Performance

Response performance measures stimulus processing Researchers can measure:

Reaction Time Response Accuracy Stimulus Judgments

Response performance example: Stroop Test

In the first slide that follows, read the words aloud as quickly as you can

In the second slide that follows, name the colors as quickly as you can

In the third slide that follows, name the color of ink used to print each word as quickly as you can

Read the Color Names:

Red Blue Green Yellow

Blue Yellow Red Green

Green Red Yellow Blue

Yellow Green Blue Red

Red Blue Green Yellow

Blue Yellow Red Green

Green Red Yellow Blue

Yellow Green Blue Red

Name the Colors:

Name the Color in Which Each Word is Printed:

Red Blue Green Yellow

Blue Yellow Red Green

Green Red Yellow Blue

Yellow Green Blue Red

More on Data-Collection Methods of Psychological Science: Imaging

Structure One goal of imaging techniques is to ascertain whether the

structure of the brain is intact in a particular individual. If a technique has high spatial resolution, it can provide a

highly detailed image of brain structure. Function

Another goal of imaging techniques is to ascertain whether the functioning of different structures in the brain is intact in a particular individual

If a technique has high temporal resolution, it can provide a millisecond by millisecond record of changes occurring in brain function

Imaging techniques are also used to study the relationship between brain structure, brain activity, mental activity, and behavior.

Image resolution example

From left to right: Low image (spatial) resolution to high image (spatial) resolution

Some imaging techniques

Electrical Recordings Electroencephalogram (EEG)

What does electromagnetic activity in the brain look like when a person is awake? asleep? (See Chapter 4)

Event-related potentials (ERP’s): How does electromagnetic activity in the brain change in

response to particular stimulus, like a familiar face?

EEG’s and ERP’s have a high temporal resolution, but a low spatial resolution (15 mm).

Used in the diagnosis of epilepsy.

Graphical representation of EEG’s and ERP’s

More brain-imaging techniques CAT (computerized axial tomography): used to

determine the integrity of brain structures; good spatial resolution

MRI (magnetic resonance imaging): used to determine the integrity of brain structures; very high spatial resolution

PET (positron emission tomography): used to investigate both the structural and functional integrity of brain structures; good spatial resolution and okay temporal resolution (~ 45 seconds)

fMRI (functional MRI): used to investigate both the structural and functional integrity of brain structures; very high spatial resolution and very good temporal resolution (3-5 seconds)

PET and the Talking Left Hemisphere

Brighter areas indicate higher activity levels

During hearing words, for example, auditory cortex and Wernicke’s area are most active

Magnetic Resonance Imaging (MRI)

MRI provides very high quality images

of intact human brains.

Invasive techniques for studying the brain

Clinical Case Studies Clinical neuroscience and clinical neuropsychology Cognitive neuropsychology

Experimental Interventions Lesion studies in animals Drug studies in animals and humans Electrical brain stimulation

Penfield

Ethical Considerations in Human and Animal Research

Ethical Considerations in Human Research Institutional Review Boards Informed consent: potential participants should receive

enough information to make the same decision about participating that they would have had they known all the information.

Freedom to withdraw at anytime. Anonymity and confidentiality. Debriefing. Deception.

Animal Research Ethics

Animal Welfare Proper care, minimization of pain and stress, and humane

treatment are universally supported Allegations of mistreatment in laboratories are rarely

supported by facts Studies in which animals were mistreated cannot be published

in reputable journals Animal Rights

There is no consensus over whether animals have rights that are similar to human rights

When over a thousand undergraduate psychology majors were polled, 72% supported, 18% opposed and 10% were unsure.

Miscellaneous

Replication Serendipity Reactivity Observer bias Experimenter expectancy effect Socially desirable responding