AO3 - Types of Experimental Methods

• A strength of lab experiments is that they have high control over extraneous variables as they are carried out in a fake/artificial environment (AO2), therefore cause and effect can be established between the IV (AO2) and DV (AO2) which increases the internal validity of the research.
• Another strength of lab experiments is that they are high in reliability as the experiment (AO2) can be easily repeated in the same conditions to check for consistent results.
• One weakness of lab experiments is that they lack ecological validity as they are carried out in an artificial environment (AO2). Therefore it is difficult to generalise the findings of (AO2) beyond the setting of the study, lowering the internal validity.
• Another weakness of lab experiments is that they are prone to demand characteristics, where the participants change their natural behaviour based on clues given off by the researcher (AO2) this could lead to participants choosing to either help or hinder the researcher, reducing the internal validity.
• One strength of field experiments is that they are less prone to demand characteristics as people might not know they are being watched so they are less likely to guess clues given off by the researcher and change their natural behaviour (AO2). Therefore increasing the internal validity.
• Another strength of field experiments is that they have high ecological validity as it is based in a real life setting therefore it is easier to generalise the findings beyond the setting of the study to other similar settings (AO2), increasing internal validity.
• One weakness of field experiments is that they are low in reliability as the environment is natural (AO2), it is difficult to repeat with exactly the same conditions to check for consistent results.
• Another weakness of field experiments is that they have a lower level of control over extraneous variables - although the IV is manipulated by the researcher, the research is conducted in a natural environment making it harder for extraneous variables to be controlled for, meaning that they may impact the findings. Therefore lowering the internal validity.
• One strength of natural experiments is that they provide opportunities for research that may not otherwise be undertaken for practical or ethical reasons. For example, Rutter’s study on Romanian orphans would have been unethical to manipulate unless the institutionalisation (IV) had not occurred naturally (AO2). Therefore, natural experiments contribute to a greater psychological understanding of behaviour.
• Another strength of natural environments is they can be praised for high ecological validity as natural experiments are often based in a real life setting therefore it is easier to generalise the finings beyond the setting of the study to other similar settings (AO2) increasing the external validity.
• One limitation of natural environments is that the naturally occurring event may only happen very rarely which limits opportunities for research (AO2) this means it is unlikely that the research can be repeated to check for consistent results so lacks reliability.
• Another weakness of natural experiments is that they have low control over extraneous variables as natural experiments usually take place in a natural environment (AO2). Therefore it is difficult to establish cause and effect between the IV and the DV lowering the internal validity of the study.
• Quasi can be conducted in a natural or controlled environment (field or lab). Therefore, depending on the scenario, you have to select the appropriate strengths and weaknesses.
• One limitation of quasi experiments is that they can be criticised for sample bias as the sample being studied may have unique characteristics (AO2), which may mean that it is difficult to generalise to the target population (AO2) decreasing the external validity of the study.