types of experiment

• an experiment is a study that investigates cause and effect
• the four types of psychology experiments are laboratory, field, quasi and natural
• A laboratory experiment is an experiment where the independent variable is manipulated in an artificial environment.
• in an everyday life setting there are a lot of extraneous variables
• one pro of laboratory experiments is that they have high control over extraneous variables, leading to high internal validity
•  one pro of laboratory experiments is that they provide high control over extraneous variables, leading to high internal validity. This means that they can establish a clear cause and effect relationship between the IV and the DV.
• a con of laboratory experiment is the artificial environment may mean participants behaviour is not generalisable to everyday life, meaning the study may have low ecological validity.
• When using a laboratory experiment, participants may not behave the same way they would in normal, everyday life. They may change their behaviour or answers because they know they are being studied. This means that the experiment would have low ecological validity, which is a type of external validity.
• a field experiment is an experiment where the independent variable is manipulated in a natural, everyday life setting.
• field experiments have high external and ecological validity
• Extraneous variables like these are hard to control in a field experiment, so field experiments have low internal validity.
• A quasi experiment is an experiment where the independent variable can’t be manipulated and randomly allocated to groups because it’s a personal characteristic of the participants.
• Now, in a laboratory or field experiment, professor Spence could control participant variables by using random allocation
• some of the participant variables - like level of confidence in driving - vary systematically with the level of the independent variable meaning these participant variables are confounding variables.
• A pro of a quasi experiment is that they enable researchers to study independent variables that can’t be studied in laboratory or field experiments.
•  A con of a quasi experiment is that the study may lack internal validity making it harder to establish cause and effect.
• A con of a quasi experiment is that participants can’t be randomly allocated to groups, meaning that uncontrolled participant variables might act as confounding variables.
• A big con of using quasi experiments is that the participants can’t be randomly allocated to groups which means that uncontrolled participant variables might act as confounding variables in the study. This would reduce the internal validity of the study and make it harder to establish a cause and effect.
• A natural experiment is used when it wouldn’t be practical or ethical to manipulate the independent variable, when an experiment where the independent variable is an event that has already happened and when an experiment where the independent variable isn’t manipulated and can’t be randomly allocated.
• in a natural experiment the independent variable is an event
• a natural experiment is used when it is not ethical or practical to manipulate the independent variable
• A pro of the natural experiment is    It enables researchers to study independent variables that it would be unethical or impractical to investigate in a laboratory or field experiment.