Types of Experiment

Laboratory experiment?

an experiment that takes place in a controlled environment within which the researcher manipulates the IV and records the effect on the DV (whilst maintaining control of extraneous variables)

Lab experiment - strength 1: what is there a high degree of control over?

extraneous variables - so the researcher can ensure the cause and effect relationship between the IV and DV (high level of internal validity)

Lab experiment - strength 2: what is easier in this type of experiment than in others?

replication (due to the high degree of control over extraneous variables) - easy to check the results to see if the findings were valid or just a one-off

Lab experiment - weakness 1: what do they have a low level of?

ecological validity - the environment is artificial and not like everyday life so the findings aren’t always generalisable to real life

Lab experiment - weakness 2: how might the artificial environment impact participant’s behaviour?

the participants may behave unnaturally - as they are aware they are taking part in an experiment and may behave abnormally which would lead to invalid results (also demand characteristics are likely to occur)

Field experiment?

an experiment conducted in a place familiar to the participants (natural environment) within which the researcher manipulates the IV

Mundane realism?

how closely a psychological study’s setting, materials, and procedures mirror the real world

Field experiment - strength 1: what does it have a high level of?

ecological validity - the environment is more natural so participants behaviour will be more valid and authentic (especially when they are unaware they are being observed)

Field experiment - weakness 1: what is there low control over?

extraneous variables hard to control - cause and effect between the IV and the DV is much more to difficult to establish and precise replication is usually not possible

Field experiment - weakness 2: what are there key issues around?

ethics - if participants are unaware they are being studied they cannot consent and such research might be an invasion of their privacy

Natural experiment?

an experiment where the IV is a naturally occurring event and so is not manipulated by the researcher and would’ve happened even if the researcher had not been there

Natural experiment - strength 1: what do they allow to happen?

research that may not otherwise be undertaken for practical or ethical reasons

Natural experiment - strength 2: what do they have a high level of?

ecological validity - because they involve the study of real-life issues and problems as they happen

Natural experiment - weakness 1: what might be rare?

the naturally occurring event may be very rare - this reduces its replicability and limits the scope for generalising findings to other similar situations

Natural experiment - weakness 2: what can’t you do with participants?

can’t randomly allocate them - lowers the internal validity as researchers may be less sure whether the IV affected the DV

Quasi-experiment?

an experiment with an IV that is based on pre-existing demographic difference between the participants

Quasi-experiment - strength 1: what is there a high degree of control over?

extraneous variables - often carried out under controlled conditions so the researcher can ensure the cause and effect relationship between the IV and DV (high level of internal validity)

Quasi-experiment - strength 2: what is easy?

replication - highly controlled environment with a standardised procedure so we can check to see if the results were valid or just a one-off

Quasi-experiment - weakness 1: what are there high levels of?

high demand characteristics - artificial environment so they are aware that they are taking part in an experiment so they are more likely to guess the aim

Quasi-experiment - weakness 2: what can’t they do to participants?

can’t randomly allocate participants to conditions - therefore their may be cofounding participant variables that will lower the internal validity