Psychological Research

Psychology is a science – must be Empirical. Hindsight bias – the tendency to think we knew something all along when finding out about research findings. Two overall types of research… – Basic research – explores questions that are of interest to psychologists, but are not intended to have immediate, real-world applications. – Applied research – explores questions that have a clear, practical application.

Operational definitions – When you operationalize a variable, you explain how you will measure it. Validity – Research is valid when it measures what the researcher set out to measure. Reliable – Research is reliable when it can be replicated. If the researcher conducts the same research he/she should get similar results.

Sampling Sampling – the process by which participants are selected for research. Population - the entire group from which the sample will be selected. Representative sample – A group of participants that accurately represent the population. Random selection – every member of the population has an equal chance of being selected. The larger the sample the better – more likely to represent the population. Stratified sample – sampling that ensures that the sample represents the population on some criteria… – Example – race or age

The Case Study Case Study – An observational technique in which one person is studied in depth in hopes of revealing universal principles. Examples: Jean Piaget & Children Chimpanzees & Language Disadvantage – An individual may not be typical. Smokers die younger School shootings

The Survey Survey - A technique for ascertaining the self reported attitudes or behaviors of people, usually by questioning a representative, random sample of them. advantage disadvantage – wording effects… – disclosure

Surveys tell us a great deal… 72% Think there is too much TV violence. 84% favor equal job opportunities for homosexual people. 89% say they face high stress 95% believe in God. 96% would like to change their apprearance. 70% of year olds support gay marriage, but only 30% of those over 50 support gay marriage.

Wording… Not allowing or forbidding Censorship or more restrictions Aid to the needy or welfare Affirmative action or preferential treatment Pro-choice or pro abortion

Naturalistic Observation Naturalistic observation – Observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation. Examples… Disadvantages?

The case study, survey, and naturalistic observation do not explain behavior, they describe it.

Correlation Correlation – a measure of the extent to which two factors vary together, and thus of how well either factor predicts the other. The correlation coefficient is the mathematical expression of the relationship, ranging from -1 to +1. Scatterplot – a graphed cluster of dots, each of which represents the values of two variables.

Negative and Positive Correlation

Negative or Positive Correlation? The more TV is on in the homes of young children, the less time they spend reading. The more sexual content teens see on TV, the more likely they are to have sex. The longer children are breast-fed, the greater their later academic achievement. The more income rose among a sample of poor families, the fewer psychiatric symptoms their children experienced.

The Irresistible Error… Assuming that correlation proves causation. Correlation is NOT Causation!

Illusory Correlation Illusory correlation – When we believe there is a relationship between two things, we are likely to notice and recall instances that confirm our belief. This arises from our natural tendency to make sense of the world. – Flip a quarter six times… HHHTTT or HTTHTH or HHHHHH? Lottery – Evelyn Marie Adams of New Jersey One in one billion!

Experimentation Experiment – a research method in which an investigator manipulates one or more factors (independent variables) to observe the effect on some behavior or mental process (the dependent variable).

Dependent & Independent Variables Independent variable – the experimental factor that is manipulated – the variable being studied. Dependent variable – the outcome factor; the variable that may change in response to manipulations of the independent variable. In testing a hypothesis, researchers manipulate the independent variable and measure the dependent variable. Example - Mothers and breast milk…

Placebo effect – experimental results caused by expectation. Single-blind procedure – an experiment in which both the research participants are ignorant (blind) concerning which participants have received treatment or a placebo. Double-blind procedure – an experiment in which both the research participants and the research staff are ignorant (blind) concerning which participants have received treatment or a placebo. Experimental condition – the condition of an experiment that exposes participants to the treatment. Control condition – the condition of an experiment that contrasts with the experimental condition and serves as a comparison for evaluating the effect of the treatment.

Statistical Reasoning… Mode – the most frequently occurring score(s) in a distribution. Median – the middle score in a distribution; half scores are above – half below… Mean – the average of a distribution – scores are added and divided by # of scores.

Statistical Reasoning… Range – the difference between the highest and lowest scores in a distribution. Standard deviation – a measure of how much scores vary around the mean score. Statistical significance – a statement of how likely it is that an obtained result happened by chance.

When can you generalize from a sample? 1.Representative samples are better than biased samples. 2.Less-variable observations are more reliable than those that are more variable. 3.More cases are better than fewer cases.

Correlation Study 1.In this experiment, the class represents what type of SAMPLE? What is the POPULATION the sample is taken from? 2.Is there a POSITIVE, NEGATIVE, or NO CORRELATION between foot size and height? 3.In this experiment, what is the INDEPENDENT VARIABLE? What is the DEPENDENT VARIABLE? 4.What is the MODE of the shoe sizes? 5.What is the MEDIAN of the shoe sizes in the class? 6.What is the MEAN of the shoe sizes in the class? 7.What is the RANGE of the shoe sizes in the class? 8.What is a true statement you can make about shoe sizes and height?