Experimental Methods Flashcards
Experimental Methods Introduction
The experimental method involves the manipulation of variables to establish cause and effect relationships .
The key features are controlled methods and the random allocation of participants into controlled and experimental groups .
An experiment is an investigation in which a hypothesis is scientifically tested .
In an experiment the IV is manipulated and the DV is measured , extraneous variables are controlled .
The experiment is objective so the views and opinions of the researcher should not affect the study . This makes the data more valid
Lab Experiment
This is an experiment conducted under highly controlled conditions , where accurate measurements are possible .
The researcher decides where the experiment takes place , at what time , with which participants , in what circumstances and using a standardized procedure .
Participants are randomly allocated to each independent group .
Strengths and Limitations of Lab Experiment
Strengths - It’s easier to replicate a laboratory experiment , this is because a standardized procedure is used.
They allow for control over extraneous and independent variables .
Limitations - The artificiality of the setting may produce unnatural behavior that’s different from real life . This would make it difficult to generalize .
Demand characteristics or experimenter bias may effect results .
Field Experiment
Field Experiments are done in the everyday environments of people .
The experimenter manipulates the IV however in a real life setting .
Strengths and Limitations of Field Experiment
Strengths - Behavior is more likely to be similar to that of real life .
Lower demand characteristics may affect the results as participants don’t know they are being studied .
Limitations - Less control over extraneous variables which can affect the results.
Natural Experiment
Natural experiments are conducted at the everyday environment of the participant , however the experimenter has no control over the IV
Strengths and Limitations of Natural Experiment
Strengths - Behavior more likely to be similar to that of real life .
Lower chance of demand characteristics affecting the results .
Can be used in places where it’s unethical to manipulate the IV.
Limitations - These can be more expensive and time consuming than lab experiments .
No control over extraneous variables that can affect the results .
Key Terminology
Ecological Validity - The degree to which an investigation represents real life experiences .
Experimenter Effects - These are the ways that the experimenter can accidentally influence the participant through
their appearance , behavior etc .
Demand Characteristics - The clues in an experiment that lead the participants to think they know what the researcher is looking for .
Independent Variable - The variable the experimenter manipulates , which can have a direct impact on the dependent variable .
Key Terminology 2
Dependent Variable - Variable the experimenter measures , this is the outcome of a study .
Extraneous Variables - All variables which are not the independent variable , but could still affect the results of the experiment . EV’s should be controlled where possible .
Confounding Variables - Variable(s) that have affected the results (DV), apart from the IV . A confounding variable could be an extraneous variable that hasn’t been controlled .
Key Terminology 3
Random Allocation - Randomly allocating participants to independent variable conditions , so that all participants have an equal chance of taking part in each condition.
The principle of random allocation is to avoid any bias in the way the experiment could be carried out and to also limit the effects of participant variables.
Order Effects - Changes in participants performance due to them repeating the same or similar test more than twice .
Examples may include ;
Practice Effect - An improvement in performance due to repeating the same task
Fatigue Effect - A decrease in performance due to repeating the same task
