Types of experiments and ethical guidelines

Informed Consent - 1. You must have permission from a subject to experiment on them

Informed Consent - 1. You must have permission from a subject to experiment on them

2. They should be informed of the purpose of the experiment

3. Consent is not needed if subjects are observed doing everyday things

Debriefing - All participants should be told the results of the study and what role they played in it

Protection - All participants should be protected from mental and physical harm.No frightening, embarassing, or offending participants should occur.

Deception - 1. Subjects should not be deliberately misled

2. Sometimes deception is unavoidable but should be used as minimal as prossible

Confidentiality - Participants should remain anonymous. No names should be used in report

Withdrawal - 1. Subjects should be allowed to quit the experiment at any time

2. Data should not be used from subjects who quit

Experiment

Where an experimenter manipulates an IV in order to monitor its effect on a DV. It tests a cause

Laboratory Experiment

Experiments conducted in a specially controlled setting. Researchers control all the variables except the IV. Whatever effect the IV has is called the DV. Ps are usually always aware of being observed, however they may not necessarily know "what" is being measured.

5 strengths of laboratory experiments

1. There is a high level of control which means that extraneous variables can be minimised. As the only thing being changed between laboratory conditions is the IV, researchers can be more certain that the DV is caused by the IV, rather than anything else. 2. Laboratory experiments have high internal validity as the high level of control and the altering of only the IV between conditions allows researchers to be more sure they are measuring what they wish to measure. 3. Changes to the IV make it possible to measure the effect on the DV. This allows cause and effect statements to be made and relationships established between two variables established. This is positive as it enables treatments and changes to behaviour to be identified. 4. They are easier to replicate and repeat to check the reliability of findings as procedures are standardised. 5. Allows researchers to create and measure experiments that would normally be difficult to set up or observe in real life.

4 weaknesses of laboratory experiments

1. Laboratory experiments may result in people behaving in an unnatural way different to what they would really be like in real life settings. Some tasks in laboratory experiments may be contrived so the resulting behaviours may lack internal validity and not be indicative of real life.

2. Ps are aware they are being observed and this could lead to demand characteristics and Ps behaving in a way that is not representative of true behaviour. Therefore laboratory experiments may lack internal validity as the behaviour being measured is not the real behaviour.

3. Laboratory experiments lack ecological validity and mundane realism due to the artificial setting and tasks. 4. Researchers involved in the experiment may result in experimenter effects where their own expectations influence the Ps' behaviour.

Field experiment

Field experiments are controlled experiments which are conducted in everyday environments outside the laboratory. The IV is still manipulated by researchers and the effect on the DV is measured. Ps may or may not be aware of being observed in field experiments with behaviour believed to be more natural than laboratory experiments generally.

4 strengths of field experiments

1. Field experiments have higher ecological validity as they tend to be conducted in more natural settings. 2. Field experiments allow researchers to measure more natural behaviour in people due to the more natural environment. Therefore the findings may have high internal validity as the behaviour observed may be more "real" than in laboratory settings. 3. When Ps are unaware of being observed this helps minimise the risk of demand characteristics. 4. There is still some control over environment and manipulation of the independent variable is still possible. This allows researchers to make statements about cause and effect.

4 weaknesses of field experiments

1. There is less control over field experiments compared to lab experiments meaning extraneous variables might affect the independent variable (IV) or dependent variable (DV). This means researchers cannot always be certain that changes to the DV are due to changes in the IV. 2. Replication of field experiments is harder and therefore it is more difficult to check the reliability of findings. 3. Ethical issues arise when Ps are not aware of being observed as part of a study and therefore there is deception occurring. Informed consent may not always be possible either which breaches ethical guidelines. 4. If Ps are aware of being observed demand characteristics are still possible from Ps.

Natural / quasi experiment

An experimental method, in which, rather than being manipulated by the researcher, the IV studied is naturally occurring. Some examples of naturally occurring variables are gender and age. Ps may or may not be aware of being observed.

4 strengths of natural / quasi experiments

1. Natural experiments allow researchers to measure things that may be unethical to set up in a laboratory e.g. adoption studies or smoking effects. 2. When Ps are unaware of being observed the behaviour is high in internal validity and more realistic as demand characteristics are minimised. 3. natural experiments have high ecological validity as the settings are much more natural.

4 weaknesses of natural / quasi experiments

1. Natural experiments are harder to replicate meaning the reliability of findings cannot be checked. 2. There is no control over the experiment by researchers as they merely observe. This means a number of extraneous variables could be contributing to the DV resulting in low internal validity. This makes it difficult to infer cause and effect. 3. There is no control over the allocation of Ps between conditions. Therefore individual differences are harder to control for. 4. If Ps are unaware of being observed this raises ethical issues as informed consent is not gained.

What is the experimental method?

A research method using manipulation of variables to determine cause and effect.

Independent variable (IV)

The variable that is manipulated by the experimenter to test its effect on the dependent variable.

Dependent Variable (DV)

The effect of the IV, or what is measured, in an experiment.

Operationalisation of variables

Being able to define variables in order to manipulate the IV and measure the DV, e.g. performance on a memory test might be operationalised as 'the number of words remembered from a list of words'.

Extraneous variable (EV)

Any variable other than the IV that could cause a change in the DV and alter the results. These can include: participant variables (e.g. age, IQ), participant effects (e.g. screw you, Hawthorne), investigator effects (e.g. Greenspoon), situational variables (e.g. time, temperature).

Confounding variable

A variable other than the IV which affects the DV in a similar way to the IV, and is often mistaken for the IV.

Why standardised procedures are important

When instructions and procedures are not uniform for all participants, these can introduce extraneous variables into the study. Keeping procedures standardized helps to ensure that the IV is causing the DV, not something else.

replicability

Being able to repeat a study and obtain the same / similar results.

What pilot studies are and why they are used

A trial run of research with a small number of participants for researchers to make necessary adjustments and to save wasting valuable resources.

What a control group is and why they are used

The group in an experiment that is exposed to the same conditions as the experimental group except for the IV. Control groups are used to find the baseline of behaviour, so the researcher can see how much the IV has caused the DV.