1.3 Research in psychology Experimental Methods

Pgs. 25 - 29

 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.



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 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  Except experimental hypothesis if demonstrate effect due to IV manipulation. 

 1. 2. 3. 4. 5.

Identify the IV and DV in each of the experimental hypotheses: People are more likely to make a risky decision when they are in a group than when they are alone. An increase in carbohydrates decreases ones ability to concentrate. People will react more quickly to an auditory stimulus than a visual stimulus. Lack of sleep will affect learning new word negatively. 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.

 Laboratory

experiments  Field experiments  Natural 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?

 Pros     

Used in Social Psychology Takes place in natural environments, but IV is still manipulated. e.g. Piliavin and Rodin (1969) helping behavior in a New York Subway Kitty Genevese 1964 The bystander effect

 Cons 

Cannot control all variables

 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



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



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. 



Researcher Bias or observer bias- the researchers sees what he wants to see. 



To overcome – Single Blind control – participants do not know what the study is about.

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

 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.

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.