1.3 Research in Psychology: Experimental Methods Pgs

Artificiality is when the procedure is not something that would occur in real life. Another term for this is mundane reality. Ecological validity is when the results that are seen in the laboratory predict what will happen outside the laboratory. Many experiments lack ecological validity because of the controls that are in place during an experiment.

The Use of Experiments in Psychology GOAL: establish cause and effect relationship between two variables Experiment: Quantitative research (generates numerical data) Variables Independent Variable (IV): variable being manipulated or changed in the study Dependent variable (DV): the variable that is being measured Variables must be Operationalized, i.e. they must be measurable.

Independent vs Repeated Measures Independent samples: the two variables are independent of each other e.g. control group vs experimental group Repeated Measures: One sample group: before and after affects.

Independent Design Pro: Avoids order effects (such as practice or fatigue) as people participate in one condition only. If a person is involved in several conditions they may become bored, tired and fed up by the time they come to the second condition, or becoming wise to the requirements of the experiment! Con: More people are needed than with the repeated measures design (i.e. more time consuming). Con: Differences between participants in the groups may affect results, for example; variations in age, sex or social background. These differences are known as participant variables (i.e. a type of extraneous variable).extraneous variable [

Repeat measures The same participants take part in each condition of the independent variable. This means that each condition of the experiment includes the same group of participants. Pro: Fewer people are needed as they take part in all conditions (i.e. saves time) Con: There may be order effects. Order effects refer to the order of the conditions having an effect on the participants’ behavior. Performance in the second condition may be better because the participants know what to do (i.e. practice effect). Or their performance might be worse in the second condition because they are tired (i.e. fatigue effect). [

Apply your knowledge – pg 26 Operationalize your variables by considering each of the following descriptions and deciding whether it is an example of aggression or not. Two men fight over a parking space A football player kicks the ball into a goal Two girls give a boy the “silent treatment” on the playground A man kicks the back of the car when it will not start Three students have a heated debate about whether global warming is happening. Know write a well worded definition of aggression.

The Experiment The Experimental Hypothesis predicts the relationships between the IV and the DV Null Hypothesis: predicts that there will be no results or that the results will be due to chance. The Control Group has no experimental actions applied to it. WE CAN NEVER PROVE ANYTHING…..WE CAN ONLY DISPROVE. Accept the null hypothesis Refute the null hypothesis Accept experimental hypothesis if demonstrate effect due to IV manipulation.

Be a Thinker pg 27 Identify the IV and DV in each of the experimental hypotheses: 1.People are more likely to make a risky decision when they are in a group than when they are alone. 2.An increase in carbohydrates decreases ones ability to concentrate. 3.People will react more quickly to an auditory stimulus than a visual stimulus. 4.Lack of sleep will affect learning new word negatively. 5.Children who have watched a film with a model hitting a blow-up doll will exhibit more aggressive acts toward a blow-up doll than children who have not watched the film.

Different Kinds of Experiments Laboratory experiments Field experiments Natural experiments

Laboratory experiments Pros: Easy to control Easy to replicate Cons Artificial environment What is the ecological value? Would your result stand up outside of a lab setting?

Field Experiment Pros Used in Social Psychology Takes place in natural environments, but IV is still manipulated. The bystander effect (7:04)bystander effect Kitty Genevese 1964Kitty Genevese e.g. Piliavin and Rodin (1969) helping behavior in a New York Subway (3:25). Piliavin and Rodin Cons Cannot control all variables

Natural Experiment Natural experiment or quasi – the researchers have no control over the variables Research on stoke patients Cannot change gender Children who have been separated from their parents due to war

Points to consider with experiments Confounding Variables: undesirable variables that influence the relationship between the IV and DV. Artificiality – the situation is so unlikely that one has to wonder if there is any validity to the study

Points to consider with experiments Three of the most common confounding variables: Demand characteristics or Hawthorn Effect – participants behave in a manner that they think they should to meet the demands of the study. To overcome – Single Blind control – participants do not know what the study is about. Researcher Bias or observer bias- the researchers sees what he wants to see. To overcome – Double Blind control – the participants & researcher do not know who is in the control group vs. experimental group Participant Variability – sample represents same characteristics Overcome – random sampling

Correlation studies Not all experiments can be carried out, however, data can reveal relationships between two variables = Correlations Correlation – as one variable changes the other variable changes. This does not mean there is a cause and effect. Positive correlation: as X increases Y increases Negative correlation: as X increases, Y decreases Note – no IV is manipulated, thus there is not cause and effect.

Advantages of Correlation Studies 1.They are simple and provide a numerical representations of the relationship that can be easily understood 2.They allow the study of a number of variables that cannot be manipulated experimentally.