Psychology - research methods

What is a hypothesis?

• A statement which clearly describes the relationship between variables as stated by the theory (e.g. drinking SevenUp soda causes people to become more talkative)

• Directional hypothesis: researcher clearly states the difference anticipated between two conditions (include words like more, less, higher, faster, etc)

• Non-directional hypothesis: states a difference between conditions but does not specify the nature of this difference

Operationalisation of variables

• ensuring the variables are measurable as possible (e.g. adding units)

• Example of an operationalised hypothesis: After drinking 300ml of SevenUp soda, participants will say more words in the next 5 minutes than participants who drink 300ml of water

Laboratory experiments

• Laboratory experiments are conducted in highly controlled environments where the scientists manipulate the independent variable

• Strength: have high control over extraneous variables so researchers can ensure that any effect of the dependent variable is most likely a result of manipulation of the IV, so lab experiments high internal validity as scientists can demonstrate cause and effect

• Limitation: lack generalisability as the environment may not reflect everyday life, so in an unfamiliar context the participant may behave unusually, meaning experiment has low external validity as findings cannot be generalised beyond the controlled research setting. Participants might also exhibit demand characteristics due to awareness of being tested.

Field experiments

• Field experiments take place in the participants' usual environment, but the researcher manipulates the IV

• Strength: higher mundane realism as the environment is more natural or typical for the participant, so behaviour produced may be more valid, especially since participants are unaware of being studied so this means they have high external validity.

• Limitation: induce ethical issues as participants are unaware of being studied, so they cannot provide consent and research might constitute as an invasion of privacy

Natural experiments 

• Natural experiments are when the researcher measures the effect of an IV on a DV but has no control over the IV, the research setting does not necessarily have to be natural (participants may be tested in a lab)

• Strength: provide opportunities for research that could not otherwise be undertaken for practical/ethical reasons (e.g. Rutter's study of institutionalised Romanian adoptees) so have high external validity as they involve studying real-world issues

• Limitation: Naturally occuring events may only happen rarely, reducing the opportunity for researching and limiting the scope for generalising findings to other similar situations

Quasi

• Quasi experiments have an IV based on existing difference between people (e.g. age, gender) which simply exists and cannot be changed

• Strength: happen in controlled conditions so can be replicated easier due to the high level of control, ensuring new extraneous variables are not introduced when repeating the experiment

• Limitation: cannot randomly allocate participants to conditions so there may be extraneous variables which are unaccounted for